Research Article UV-B Radiation Impacts Shoot Tissue Pigment Composition...

Hindawi Publishing CorporationThe Scientific World JournalVolume 2013 Article ID 513867 10 pageshttpdxdoiorg1011552013513867

Research ArticleUV-B Radiation Impacts Shoot Tissue Pigment Composition inAllium fistulosum L Cultigens

Kristin R Abney1 Dean A Kopsell1 Carl E Sams1 Svetlana Zivanovic2

and David E Kopsell3

1 Plant Sciences Department The University of Tennessee 2431 Joe Johnson Drive Knoxville TN 37996 USA2Department of Food Science and Technology The University of Tennessee 2605 River Drive Knoxville TN 37996 USA3Department of Agriculture Illinois State University Normal IL 61790 USA

Correspondence should be addressed to Dean A Kopsell dkopsellutkedu

Received 1 February 2013 Accepted 3 March 2013

Academic Editors L Fodorpataki M C Martınez-Ballesta and B Muries

Copyright copy 2013 Kristin R Abney et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Plants from the Allium genus are valued worldwide for culinary flavor and medicinal attributes In this study 16 cultigensof bunching onion (Allium fistulosum L) were grown in a glasshouse under filtered UV radiation (control) or supplementalUV-B radiation [70 120583molsdotmminus2sdotsminus2 (268Wsdotmminus2)] to determine impacts on growth physiological parameters and nutritionalquality Supplemental UV-B radiation influenced shoot tissue carotenoid concentrations in some but not all of the bunchingonions Xanthophyll carotenoid pigments lutein and 120573-carotene and chlorophylls a and b in shoot tissues differed between UV-B radiation treatments and among cultigens Cultigen ldquoPesoenyjrdquo responded to supplemental UV-B radiation with increases in theratio of zeaxanthin + antheraxanthin to zeaxanthin + antheraxanthin + violaxanthin which may indicate a flux in the xanthophyllcarotenoids towards deepoxydation commonly found under high irradiance stress Increases in carotenoid concentrations wouldbe expected to increase crop nutritional values

1 Introduction

Fruits and vegetables have varying levels of phytonutrientsin addition to vitamins and minerals Two important classesof phytonutrients are carotenoid and chlorophyll pigmentsThe primary carotenoids found in leaf tissue of most plantspecies include zeaxanthin antheraxanthin violaxanthinlutein 120573-carotene and neoxanthin [1] Chlorophylls are thedominant pigments in plants and serve primary roles inphotosynthesis These compounds are very effective antiox-idants and help prevent certain types of cancers and agingeye diseases like macular eye degeneration [2 3] Howeverthe chemical structures of these pigments also give them theability to donate electrons and effectively become prooxi-dants under certain conditions [4] Allium species containchlorophyll and carotenoid pigments in shoot tissues [5] andalso contain different levels of sulfur-containing compoundswhich prevent certain cancers [6] While all higher plantscontain chlorophylls and carotenoids genetic variations for

pigment accumulations exist both within and among plantspecies Within any given crop species there can be multiplelandraces accessions and cultivars or collectively culti-gens These variations are important to advancements inplant development programs for increased nutrition diseaseprevention or other factors However cultigens will reactdifferently under almost any given stress

The absorption of light by chlorophyll and antennapigments and the transfer of excitation energy to the reactioncenters of PSII and PSI are the initial steps in photosynthesisThe photosynthetic apparatus has the ability to react to manydifferent environmental stimuli especially changes in lightintensity Under conditions of high light stress photosyn-thetic systems are saturated and excess energy needs tobe diverted to avoid potential damage [7] Carotenoids areunsaturated long chain polycarbons which protect the photo-synthetic apparatus from high light excitation by quenchingfree radicals functioning in nonphotochemical quenching

2 The Scientific World Journal

and dissipating excess thermal energy [7 8]The xanthophyllcycle or violaxanthin cycle is the mechanism by whichplants regulate light energy available for photosynthesis Inintense light situations violaxanthin is rapidly and reversiblyconverted to zeaxanthin via antheraxanthin Zeaxanthin is adirect quencher of chlorophyll excited states and can preventphotooxidative stress and lipid peroxidation [7]

Higher amounts of UV-A (380ndash320 nm) and UV-Bradiation (280ndash320 nm) may influence the accumulation ofplant compounds used to combat light stress Carotenoidmetabolites not only protect plants from excess UV radiationbut also can protect humans from UV radiation whentranslocated to subdermal skin tissues [9] What remainsuncertain is the impact of increased UV radiation on growthand development and nutritional values of cultivated crops[10] Previous studies have demonstrated impacts of UVradiation on plant performance cellular structures andpigment accumulations In a study by Yuan et al [11] 20cultivars of wheat (Triticum aestivum L) were grown underUV-B radiation stress to determine possible detrimentalinfluencesMost wheat cultivars responded negatively to UV-B radiation however several cultivars showed increases inplant height and biomass Structural changes like rupturedchloroplast envelopes have been noted in UV-sensitive ricecultivars (Oryza sativa L) when exposed to UV stress [12]Increases in UV radiation can delay flowering and harvesttimes among different cultigens of bush beans (Phaseolusvulgaris L) [13] Bush beans grown under UV radiationshowed decreases in fruit size and yield when compared tocultivars not grown under UV radiation stress Tomatoes(Solanum lycopersicum cv DRW 5981) grown using UV-Bblocking filters showed increases in lycopene and 120573-carotenewhile fruits of the same variety showed decreases in lycopenephytoene and phytofluene when grownwithout UV-B block-ing filters [14] The tomato cultivar ldquoHP1rdquo accumulated morethan twice the amount of lycopene in fruit tissues whengrown under no UV-B radiation Results from such studiesdemonstrate impacts on nutritional quality from excess UVradiation

Allium species are valued worldwide for culinary fla-vor and medicinal attributes Plants in this genus havebeen important to multiple cultures for centuries Alliumshave high levels of nutritionally important secondary plantmetabolites which convey numerous health benefits Forexample bulb onions (Allium cepa L) contain high levels offlavonoids [15] S-alk(en)yl-L-cysteine sulfoxides [16] and avariety of volatile antioxidant compounds [17] However nostudies to date have measured the impact of UV radiationon the production of nutritionally important pigments inAlliums Allium fistulosum is consumed in part for its shoottissues as well as pseudostems Carotenoid and chlorophyllcompounds are present in the shoot tissues ofAfistulosum [518] Therefore the objectives of this project were to examineboth environmental and genetic responses to elevated UV-B radiation among a large subset of A fistulosum cultigensResponses were noted for plant height shoot tissue biomassphotochemical efficiency (119865V119865119898) and concentrations ofcarotenoid and chlorophyll pigments in the shoot and pseu-dostem tissues

2 Methods and Materials

21 Plant Culture On December 16 2008 seeds of 16different A fistulosum cultigens were sown in 15 cm potsholding soilless media in a glasshouse in Knoxville TNUSA (35∘961015840N Lat) which blocked UV-wavelengths (280ndash380 nm)Thephotosynthetically active radiation (PAR) in theglasshouse averaged 540 120583molsdotmminus2sdotsminus2 (Apogee Nanologgermodel ANL Apogee Instruments Inc Roseville CA USA)The cultigens included eight accessions [PI 274254-05GIPI 462345-05GI (Jionji Negi) PI 546343-90U01 (GA-C 76)PI 546228-06GI (Improved Beltsville Bunching) PI 280562-04GI (Pesoenyj) PI 436539-06GI (Zhang Qui Da Cong)PI 462357-06GI (Shounan) and G 30393-06GI] from theUSDA-ARS National Plant Germplasm Repository (GenevaNY USA) four cultivars (ldquoLong White Bunchingrdquo ldquoFeastPerformerrdquo and ldquoParaderdquo) from Seedway LLC (Hall NYUSA) and four cultivars (ldquoWhite Spearrdquo ldquoEvergreen HardyWhiterdquo ldquoDeep Purplerdquo and ldquoIshikura Improved F1rdquo) fromJohnnyrsquos Selected Seeds (Winslow ME USA) The seedlingswere watered daily for the duration of the experiment OnJanuary 10 2009 the seedlings were thinned to two plantsper pot and fertilized with a nutrient solution containing(mgsdotLminus1) N (105) P (915) K (1173) Ca (802) Mg (246) S(320) Fe (05) B (025) Mo (0005) Cu (001) Mn (025)and Zn (0025) [19] Each pot was fertilized once a weekfor the duration of the experiment with 100mL of nutrientsolution The experimental design was a split plot arrangedas a randomized complete block UV-B treatments were themain plots and A fistulosum cultigens were the subplots Sixindividual plants per cultigen composed a replication withfour replications randomly assigned to each UV-B treatment

Supplemental UV-B radiation (313 nm) was provided bybanks of commercially available UV-B 313 lamps (Q-PanelLab Products Cleveland OH USA) and treatment beganon January 27 2009 delivering 70120583molsdotmminus2sdotsminus2 (268Wsdotmminus2)of UV-B (Spectroradiometer Model SPEC-UVPAR ApogeeInstruments Inc Roseville CA USA) to the treated plantsTo control pests in the greenhouse the beneficial insectspecies of Hypoaspis miles and Neoseiulus cucumeris wereused to control thrips whileOrius insidiosuswas used to helpcontrol aphidsThese insectswere first released on January 232009 and were released every two weeks thereafter

On March 3 2009 all of the bunching onion culti-gens were harvested Six plants were harvested from eachreplication Fresh weights and plant heights were taken andaveraged for each replication One measure of 119865V119865119898 wastaken from each of the harvest plants at the midpoint of plantheight using a modulated fluorometer (OS1-F1 ModulatedFluorometer Opti-Sciences Hudson NH USA) The 119865V119865119898value is an indication of photoinhibition and overall planthealth All plants were harvested and pseudostem and leaftissue were separated The samples were immediately placedin a minus20∘C freezer before being moved to a minus80∘C freezerwithin 8 h

22 Pigment Extraction and Determination Tissue pigmentswere extracted according to Kopsell et al [20] and analyzed

The Scientific World Journal 3

according to Kopsell et al [5] The samples were freeze-driedand ground with a mortar and pestle with liquid nitrogenA 010 g subsample was rehydrated with 08mL of ultra-pure H

2

O The samples were incubated for 20min before08mL of ethyl-120573-81015840-apo-carotenotate (Sigma Chemical CoSt Louis MO USA) was added as an internal standardto establish extraction efficiency For pigment extraction25mL of tetrahydrofluran was added to the sample Usinga Potter-Elvehjem tissue grinding tube (Kontes VinelandNJ USA) the samples was homogenized in an ice bath todissipate heat generated from maceration The tubes werethen centrifuged in a clinical centrifuge (Centrific Model225 Fisher Scientific Pittsburg PA USA) for 3min at500119892119899

The supernatant was removed and the pellet wasrehydrated with 20mL tetrahydrofluranThis procedure wasrepeated twice more until the supernatant was colorlessThe combined supernatants were reduced to 05mL undera stream of nitrogen gas and brought to a final volume of5mLwithmethanolThe sampleswere then filtered through a02 120583m Econofilter PTFE 2520 polytetrafluoroethylene filter(Agilent Technologies Wilmington DE USA) using a 5mLsyringe A 15mL aliquot was put into an amber vial andcapped prior to high performance liquid chromatography(HPLC) analysis

An Agilent 1200 series HPLC unit with a photodiodearray detector (Agilent Technologies Palo Alto CA USA)was used for pigment separation (Figure 1)The column usedwas a 250 times 46mm id 5 120583m analytical scale polymericRP-C30

with a 10 times 40mm id guard cartridge and holder(ProntoSIL MAC-MOD Analytical Inc Chadds Ford PAUSA) which allowed for effective separation of chemicallysimilar compounds The column was maintained at 30∘Cusing a thermostated column compartment All separationswere achieved isocratically using a binarymobile phase of 11methyl tert-butyl ether (MTBE) 8899MeOH and 001triethylamine (TEA) (vvv) The flow rate was 10mLminwith a run time of 53min There was a 2min equilibrationprior to the next injection Eluted compounds from a 10 120583Linjection loop were detected at 453 nm (carotenoids internalstandard chlorophyll b) and 652 nm (chlorophyll a) Datawere collected recorded and integrated using ChemStationSoftware (Agilent Technologies) Peak assignments for eachpigment were performed by comparing retention times andline spectra obtained from the photodiode array detectionusing external standards Standards included antheraxanthinneoxanthin lutein violaxanthin zeaxanthin and120573-carotenechlorophyll 119886 and chlorophyll b (ChromaDex Inc IrvineCA USA) The concentrations of the external standardswere determined spectrophotometrically using a procedureby Davies and Kost [21] Pigment data is presented on a freshmass (FM) basis

23 Statistical Analyses Statistical analyses were completedusing the GLM procedure of SAS (v 91 SAS InstituteCary NC USA) Cultigen means within each treatment wereseparated by least significant difference (LSD) at 120572 = 005Differences between cultigens means between treatments

96

5

4

32

8

1

10 20 30 40 50

40

05101520253035

7

(min)

(mAU

)

(a)

2

15

1

05

0

minus05

minus1

8

10 20 30 40 50(min)

(mAU

)

(b)

Figure 1 HPLC chromatogram of Allium fistulosum L leaf (a) andpseudostem (b) tissues at 453 nm Retention times (min) for thepigments were (1) violaxanthin 552min (2) neoxanthin 581min(3) antheraxanthin 759min (4) chlorophyll b 851min (5) lutein933min (6) zeaxanthin 1131min (7) chlorophyll a 1390min (8)ethyl-120573-81015840-apo-carotenoate (internal standard) 1932min and (9)120573-carotene 4846min HPLC conditions are described in the text

were detected by using Studentrsquos t-test (119875 = 005) using JMP(v 701 SAS Institute)

3 Results and Discussion

31 Shoot Tissue Biomass Significant differences were foundamong cultigens (119865 = 667 119875 lt 0001) for shoottissue height but no differences were found between theUV-B treatments or the interaction between the cultigenand UV-B radiation treatment (Table 1) Only one cultigen(GA-C 76) differed significantly between UV-B radiationtreatments for shoot tissue height ldquoLong White Bunchingrdquodemonstrated the greatest growth in shoot tissue heightunder both UV-B radiation treatments while ldquoG 30393-06GIrdquo had the shortest final shoot tissue height There weredifferences in shoot tissue FM between UV-B radiationtreatments (119865 = 23810 119875 lt 0001) and among cultigens(119865 = 1109 119875 lt 0001) but no difference in the treatmentby cultigen interaction (Table 1) ldquoDeep Purplerdquo ldquoFeastrdquo ldquoGA-C 76rdquo ldquoIshikura Improved F1rdquo ldquoImproved Beltsville Bunch-ingrdquo ldquoJionjirdquo ldquoLong White Bunchingrdquo ldquoParaderdquo ldquoPerformerrdquoldquoPesoenyjrdquo ldquoShounanrdquo ldquoWhite Spearrdquo ldquo274254-05GIrdquo and


ldquoG 30393-06GIrdquo all showed decreases in shoot tissue FMwith exposure to the UV-B radiation treatment Significantdecreases in shoot tissue biomass from the UV-B treatmentwould indicate a radiational stress had occurred in the bunch-ing onion cultigens in the current study The cultigens withthe greatest shoot tissue FMaccumulationswere ldquoLongWhiteBunchingrdquo and ldquoImproved Beltsville Bunchingrdquo (Table 1)

32 Shoot Tissue Carotenoid Pigment Concentrations Nocarotenoid pigments were measured in the pseudostem tis-sues of any of the bunching onion cultigens (Figure 1 datanot shown) Kopsell et al [5] also reported no carotenoidpigmentation present in bunching onion pseudostem tissuesShoot tissue zeaxanthin differed significantly among thebunching onion cultigens (119865 = 407 119875 lt 0001) (Table 2)However there were no significant changes in shoot tissuezeaxanthin in response to UV-B treatment or the interactionof the UV-B treatments and cultigens Only the cultigens ofldquoG 30393-06GIrdquo and ldquoFeastrdquo showed an increase in shoottissue zeaxanthin under the supplemental UV-B radiationas compared to control The ranges of zeaxanthin concen-trations in the bunching onions under supplemental UV-Bwere from 008mg100 g FM for ldquoDeep Purplerdquo and ldquoWhiteSpearrdquo to 016mg100 g FM for ldquoImproved Beltsville Bunch-ingrdquo Cultigen ldquoPesoenyjrdquo had the highest concentration ofzeaxanthin among plants grown without supplemental UVradiation at 019mg100 g FM while ldquoFeastrdquo and ldquoEvergreenHardy Whiterdquo had the lowest zeaxanthin concentrationsat 007mg100 g FM Increases in zeaxanthin could be anindication that the plants experienced radiational stress fromthe UV-B treatment Plant responses through increased zeax-anthin concentrations would be expected to help dissipateexcess energy from the photosystems [7]

Shoot tissue violaxanthin responded significantly to bothUV-B radiation treatment (119865 = 676 119875 = 00109) and culti-gen (119865 = 442 119875 lt 0001) but not to the interaction betweentreatment and cultigen (Table 2)Many of the bunching onioncultigens showed higher concentrations of violaxanthin inresponse to UV-B radiational supplementation Howeveronly one cultigen had significant increases in violaxanthinconcentrations (GA-C 76) in response to UV-B radiationtreatment Increases in violaxanthin in bunching onionsgrown underUV-B radiationmay suggest that these cultigensmay not be as susceptible to UV-B radiational damageas the other cultigens Violaxanthin concentrations undersupplemental UV-B radiation ranged from 204mg100 g FMfor ldquoGA-C 76rdquo to 059mg100 g FM for ldquoPerformerrdquo CultigenldquoPesoenyjrdquo had the highest concentrations of violaxanthin(235mg100 g FM) for bunching onions grown withoutsupplemental UV-B radiation while ldquoG 30393-06GIrdquo had thelowest violaxanthin concentrations (053mg100 g FM)

Antheraxanthin the intermediate compound in xantho-phyll cycle responded significantly to changes in UV-Bradiation treatments (119865 = 1661 119875 lt 00001) and cultigens(119865 = 468 119875 lt 0001) The majority of cultigens hadhigher antheraxanthin concentrations in response to the UV-B radiation treatment however no cultigens had significantlyhigher levels as compared to the control treatment (Table 2)

The ranges for antheraxanthin concentrations in bunchingonions grown under UV-B radiation treatment were from138mg100 g FM for ldquoPesoenyjrdquo to 079mg100 g FM forldquo274254-05GIrdquo In the plants grown without UV-B radiationldquoPesoenyjrdquo had the highest antheraxanthin concentrations(135mg100 g FM) while ldquoIshikura Improved F1rdquo had thelowest concentrations (059mg100 g FM) While changes inthis compound cannot directly tell which way the xantho-phyll cycle is fluxing increases or decreases may help predictpotential energy flow

Neoxanthin concentrations responded significantly toUV-B radiation treatment (119865 = 1213 119875 = 00008) cultigen(119865 = 320 119875 = 00003) and the interaction of UVradiation treatment and cultigen (119865 = 227 119875 = 00092)Therewere significant increases in neoxanthin from theUV-Btreatment for the cultigens ldquoFeastrdquo ldquoGA-C 76rdquo and ldquoG 30393-06GIrdquo when compared to the control treatment (Table 3)ldquoFeastrdquo showed the highest concentrations of neoxanthinunder UV-B radiation treatment (186mg100 g FM) whileldquoDeep Purplerdquo had the lowest concentration of neoxanthin(073mg100 g FM) ldquoPesoenyjrdquo showed the highest neox-anthin concentration (196mg100 g FM) compared to theother cultigens grown under the control treatment ldquoHardyEvergreen Whiterdquo had the lowest of all of the cultigens notgrown under supplemental UV-B radiation at 040mg100 gFM

Thebunching onions showed significant changes in luteinin response to UV-B treatment (119865 = 1789 119875 lt 00001)and cultigen (119865 = 234 119875 = 00070) The majority ofcultigens had higher lutein concentrations in response to theUV-B radiation treatment however only ldquoFeastrdquo and ldquoGA-C76rdquo had significantly higher lutein (Table 3) ldquoPesoenyjrdquo hadthe highest concentrations of lutein both with and withoutsupplemental UV-B radiation at 801 and 923mg100 g FMrespectively ldquoDeep Purplerdquo had the lowest concentration oflutein among bunching onions grown with supplementalUV-B radiation at 504mg100 g FM and ldquoFeastrdquo had thelowest amount of lutein for bunching onions grown withoutsupplemental UV-B radiation at 411mg100 g FM Lutein actsas an accessory pigment and is the predominant carotenoid inphotosystem (PS) II [7] Research shows UV radiation willimpact PSII functioning to a greater extent than PSI [22]Therefore increases in lutein concentrations for the cultigensin the current study may indicate increased radiational stresswithin PSII from the supplemental UV-B treatment

Concentrations of 120573-carotene showed no changes inresponse to UV treatment or cultigen (Table 3) ldquoPesoenyjrdquohad the highest concentrations of 120573-carotene in bunch-ing onions grown without UV-B radiation and ldquoIshikuraImproved F1rdquo had the lowest concentrations The range ofshoot tissue 120573-carotene levels for cultigens grown undersupplemental UV-B radiation were 280mg100 g FM forldquoShounanrdquo to 088mg100 g FM for ldquoEvergreenHardyWhiterdquoFor the cultigens that were not grown under supplementalUV-B radiation the ranges for120573-carotene concentrationwere345mg100 g FM (Pesoenyj) and 064mg100 g FM (Ever-green Hardy White) Reported mean value for 120573-carotenein shoot tissues of A fistulosum is 060mg100 g FM whilethe mean values for lutein and zeaxanthin are 114mg100 g


Table 1 Mean valuesa for shoot tissue height (cm) and fresh biomass (g) for Allium fistulosum L cultigens grown under supplemental UV-B(313 nm) light [70120583molsdotmminus2 sdotsminus2 (268Wsdotmminus2) UV-B] or UV-filtered (control) light in a glasshouse in Knoxville TN USA (35∘961015840N Lat)

Cultigen Shoot tissue height (cm) Shoot tissue fresh biomass (g)UV-B Control Pr gt |119905|b UV-B Control Pr gt |119905|

Deep Purple 4471 plusmn 549 4519 plusmn 452 ns 6454 plusmn 1702 9780 plusmn 1744 119875 = 0034

Evergreen Hardy White 3911 plusmn 196 4105 plusmn 538 ns 3865 plusmn 780 7078 plusmn 808 nsFeast 3858 plusmn 324 3996 plusmn 240 ns 4879 plusmn 1599 9046 plusmn 1385 119875 = 0008

GA-C 76 3882 plusmn 191 4413 plusmn 370 119875 = 0043 4190 plusmn 266 7300 plusmn 1553 119875 = 0008

Ishikura improved F1 3963 plusmn 112 4117 plusmn 313 ns 5493 plusmn 922 9980 plusmn 947 119875 = 0001

Improved Beltsville Bunching 4426 plusmn 169 4806 plusmn 219 ns 7686 plusmn 982 11042 plusmn 1939 119875 = 0021

Jionji Negi 3620 plusmn 182 3863 plusmn 154 ns 3805 plusmn 473 6204 plusmn 823 119875 = 0002

Long White Bunching 4968 plusmn 209 5038 plusmn 462 ns 7407 plusmn 873 11601 plusmn 2024 119875 = 0009

Parade 4213 plusmn 260 3603 plusmn 940 ns 5389 plusmn 1073 9081 plusmn 1687 119875 = 0010

Performer 3937 plusmn 236 3942 plusmn 310 ns 5474 plusmn 1108 8625 plusmn 1666 119875 = 0020

Pesoenyj 3944 plusmn 423 4454 plusmn 403 ns 2922 plusmn 930 5876 plusmn 637 119875 = 0002

Shounan 3672 plusmn 302 3714 plusmn 254 ns 3917 plusmn 356 6332 plusmn 402 119875 = 0001

White Spear 4006 plusmn 279 4242 plusmn 172 ns 5316 plusmn 1441 8742 plusmn 1058 119875 = 0009

Zhang Qui Da Cong 3662 plusmn 288 3787 plusmn 380 ns 5357 plusmn 1951 8472 plusmn 1667 ns274254-05GI 4248 plusmn 186 4379 plusmn 440 ns 4763 plusmn 434 8465 plusmn 698 119875 = 0001

G 30393-06GI 3662 plusmn 340 3567 plusmn 131 ns 5096 plusmn 863 8169 plusmn 1201 119875 = 0006

LSD005

c 577 580 1072 1933aComposition of 119899 = 6 plant samples from 4 replications plusmn standard deviation bSignificance based on paired Studentrsquos t-test among treatments ns notsignificant cLSD for differences between cultivar means 120572 = 005

Table 2 Mean valuesa for shoot tissue zeaxanthin violaxanthin and antheraxanthin (mg100 g fresh mass) for Allium fistulosum L cultigensgrown under supplemental UV-B (313 nm) light [70120583molsdotmminus2 sdotsminus2 (268Wsdotmminus2) UV-B] or UV-filtered (control) light in a glasshouse inKnoxville TN USA (35∘961015840N Lat)

Cultigen Zeaxanthin Violaxanthin AntheraxanthinUV-B Control Pr gt |119905|b UV-B Control Pr gt |119905| UV-B Control Pr gt |119905|

mg100 g fresh massDeep Purple 008 plusmn 002 010 plusmn 003 ns 125 plusmn 036 088 plusmn 042 ns 107 plusmn 031 078 plusmn 023 nsEvergreen Hardy White 010 plusmn 003 007 plusmn 002 ns 173 plusmn 061 120 plusmn 025 ns 103 plusmn 018 078 plusmn 014 nsFeast 011 plusmn 001 007 plusmn 001 P = 0010 135 plusmn 082 066 plusmn 058 ns 115 plusmn 027 092 plusmn 019 nsGA-C 76 012 plusmn 002 008 plusmn 002 ns 204 plusmn 019 134 plusmn 020 P = 0002 192 plusmn 065 127 plusmn 047 nsIshikura Improved F1 010 plusmn 005 009 plusmn 002 ns 175 plusmn 094 110 plusmn 038 ns 081 plusmn 050 059 plusmn 013 nsImproved Beltsville Bunching 016 plusmn 002 015 plusmn 004 ns 162 plusmn 054 125 plusmn 014 ns 099 plusmn 038 072 plusmn 021 nsJionji Negi 012 plusmn 006 013 plusmn 003 ns 154 plusmn 025 151 plusmn 035 ns 120 plusmn 025 078 plusmn 050 nsLong White Bunching 012 plusmn 003 011 plusmn 003 ns 089 plusmn 018 081 plusmn 042 ns 082 plusmn 013 089 plusmn 014 nsParade 010 plusmn 002 011 plusmn 002 ns 123 plusmn 050 102 plusmn 061 ns 086 plusmn 016 079 plusmn 024 nsPerformer 009 plusmn 002 010 plusmn 002 ns 059 plusmn 052 145 plusmn 060 ns 087 plusmn 006 085 plusmn 032 nsPesoenyj 012 plusmn 003 019 plusmn 006 ns 193 plusmn 033 235 plusmn 082 ns 138 plusmn 030 135 plusmn 052 nsShounan 013 plusmn 005 009 plusmn 001 ns 187 plusmn 081 104 plusmn 036 ns 118 plusmn 040 063 plusmn 030 nsWhite Spear 008 plusmn 002 008 plusmn 003 ns 100 plusmn 060 077 plusmn 047 ns 074 plusmn 013 060 plusmn 009 nsZhang Qui Da Cong 011 plusmn 004 012 plusmn 002 ns 129 plusmn 048 130 plusmn 041 ns 081 plusmn 030 074 plusmn 006 ns274254-05GI 013 plusmn 004 015 plusmn 003 ns 164 plusmn 042 127 plusmn 052 ns 079 plusmn 014 071 plusmn 033 nsG 30393-06GI 013 plusmn 003 008 plusmn 002 P = 0016 060 plusmn 051 050 plusmn 043 ns 107 plusmn 035 067 plusmn 014 nsLSD005

c ns 004 074 070 044 044aComposition of 119899 = 6 plant samples from 4 replications plusmn standard deviation bSignificance based on paired Studentrsquos t-test among treatments ns notsignificant cLSD for differences between cultivar means 120572 = 005


Table 3 Mean valuesa for shoot tissue neoxanthin lutein and 120573-carotene (mg100 g fresh mass) for Allium fistulosum L cultigens grownunder supplemental UV-B (313 nm) light [70120583molsdotmminus2 sdotsminus2 (268Wsdotmminus2) UV-B] or UV-filtered (control) light in a glasshouse in KnoxvilleTN USA (35∘961015840N Lat)

Cultigen Neoxanthin Lutein 120573-caroteneUV-B Control Pr gt |119905|b UV-B Control Pr gt |119905| UV-B Control Pr gt |119905|

mg100 g fresh massDeep Purple 073 plusmn 051 104 plusmn 059 ns 504 plusmn 148 538 plusmn 073 ns 107 plusmn 081 109 plusmn 030 nsEvergreen Hardy White 074 plusmn 047 040 plusmn 018 ns 710 plusmn 286 510 plusmn 149 ns 088 plusmn 071 064 plusmn 023 nsFeast 209 plusmn 048 079 plusmn 057 P = 0013 766 plusmn 090 411 plusmn 054 P = 0001 185 plusmn 085 104 plusmn 074 nsGA-C 76 153 plusmn 032 066 plusmn 018 P = 0003 766 plusmn 038 557 plusmn 067 P = 0002 148 plusmn 027 117 plusmn 009 nsIshikura Improved F1 063 plusmn 043 063 plusmn 030 ns 635 plusmn 318 480 plusmn 120 ns 220 plusmn 259 078 plusmn 041 nsImproved Beltsville Bunching 082 plusmn 089 060 plusmn 016 ns 695 plusmn 134 562 plusmn 065 ns 164 plusmn 095 139 plusmn 030 nsJionji Negi 092 plusmn 025 091 plusmn 036 ns 735 plusmn 165 621 plusmn 149 ns 174 plusmn 120 229 plusmn 132 nsLong White Bunching 176 plusmn 026 147 plusmn 035 ns 600 plusmn 058 505 plusmn 117 ns 169 plusmn 029 194 plusmn 056 nsParade 146 plusmn 081 087 plusmn 036 ns 636 plusmn 117 604 plusmn 147 ns 126 plusmn 014 254 plusmn 123 nsPerformer 114 plusmn 090 075 plusmn 047 ns 633 plusmn 096 560 plusmn 236 ns 128 plusmn 048 238 plusmn 165 nsPesoenyj 103 plusmn 019 196 plusmn 078 ns 801 plusmn 121 923 plusmn 259 ns 187 plusmn 020 345 plusmn 239 nsShounan 132 plusmn 071 054 plusmn 032 ns 766 plusmn 283 503 plusmn 126 ns 280 plusmn 146 110 plusmn 054 nsWhite Spear 121 plusmn 062 093 plusmn 063 ns 608 plusmn 094 470 plusmn 137 ns 149 plusmn 051 108 plusmn 060 nsZhang Qui Da Cong 075 plusmn 042 065 plusmn 029 ns 565 plusmn 144 531 plusmn 147 ns 105 plusmn 024 120 plusmn 057 ns274254-05GI 084 plusmn 037 072 plusmn 045 ns 618 plusmn 079 533 plusmn 182 ns 181 plusmn 086 186 plusmn 157 nsG 30393-06GI 186 plusmn 044 085 plusmn 062 P = 0040 602 plusmn 118 442 plusmn 069 ns 186 plusmn 077 128 plusmn 067 nsLSD005

c 078 067 ns 214 ns 154aComposition of 119899 = 6 plant samples from 4 replications plusmn standard deviation bSignificance based on paired Studentrsquos t-test among treatments ns notsignificant cLSD for differences between cultivar means 120572 = 005

FM [23] Umehara et al [24] reported 120573-carotene values inthe leaves of A fistulosum L cultigen ldquoKujyoasagikeirdquo to be463mg100 g FM 120573-carotene is an accessory pigment andis the predominant carotenoid in PSI 120573-carotene is presentin PSII but mostly in regions around the reaction center [7]Since there were no impacts on 120573-carotene concentrations inthe current study it is possible that PSI is not under as muchstress from the UV-B treatments imposed in this study [22]

The xanthophyll cycle pigments (zeaxanthin antheraxan-thin and violaxanthin) are important for the dissipation ofexcess absorbed light performed almost exclusively by ZEAPhotosynthetic rates are reduced under many environmentalstressors which increase the need for dissipation of excessabsorbed light energy [7] The ratio of zeaxanthin + anther-axanthin to zeaxanthin + antheraxanthin + violaxanthin(ZAZAV) responded significantly to cultigen (119865 = 301119875 = 00006) but not to UV-B radiation treatment orthe interaction between treatment and cultigen Significantincreases in response to supplemental UV-B were found forldquoPesoenyjrdquo ldquoG 30393-06GIrdquo had the highest ZAZAV ratioof cultigens grown under supplemental UV-B radiation andldquoIshikura Improved F1rdquo had the lowest ZAZAV ratio at 034For the cultigens not grown under UV-B radiation ldquoFeastrdquohad the highest ZAZAV ratio at 065 while ldquoJionji Negirdquohad the lowest ZAZAV ratio at 035 (Table 4) Changesin the ZAZAV ratio can identify fluxes within the xan-thophyll energy dissipation cycle An increase in ZAZAVratio shows a decrease in violaxanthin which could meanthese compounds are undergoing deepoxydation because of

high light energy [7] A study by Niyogi et al [25] helpeddemonstrate the importance of this photoprotective mech-anistic cycle In this study mutant Arabidopsis thaliana wasunable to undergo deepoxydation and converts violaxanthinto zeaxanthin which resulted in an increased sensitivity tohigher light levels While the Niyogi et al [25] study did notspecifically look at how UV-B radiation affected xanthophyllcycle functioning energy from UV wavelengths is higherthan energy from PAR wavelengths and could be expected tochange the flux between the xanthophyll pigments

Kopsell et al [5] grew many of the same bunching onioncultigens under field conditions in Knoxville TN USA andGeneva NY USA and reported similar levels of shoot tissue120573-carotene and neoxanthin as found in the current studyhowever values for violaxanthin antheraxanthin luteinchlorophyll 119886 and chlorophyll 119887 were much higher in thecurrent study than previously reported Differences in shoottissue pigments for cultigens among the two studies may beattributed to differences in growing conditions (field versusglasshouse) and the time of year the cultigens were evaluated(summer versus winter)

Epidemiological data supports the positive associationbetween increased dietary intake of plant foods high incarotenoids and greater carotenoid tissue concentrationswithlower risks of certain chronic diseases Many of these diseasesuppressing abilities can be attributed to the antioxidantproperties of carotenoids One of the most important phys-iological functions of carotenoids in human nutrition is asvitamin A precursors Provitamin A carotenoid compounds


Table 4 Mean valuesa for the ratio of zeaxanthin + antheraxanthin to zeaxanthin + antheraxanthin + violaxanthin (Z + AA + Z + V)and the ratio of chlorophyll a to chlorophyll b (chlorophyll achlorophyll b) in shoot tissues for Allium fistulosum L cultigens grown undersupplemental UV-B (313 nm) light [70120583molsdotmminus2 sdotsminus2 (268Wsdotmminus2) UV-B] or UV-filtered (control) light in a glasshouse in Knoxville TNUSA (35∘961015840N Lat)

Cultigen Z + AA + Z + V Chlorophyll achlorophyll bUV-B Control Pr gt |119905|b UV-B Control Pr gt |119905|

Deep Purple 048 plusmn 001 051 plusmn 019 ns 125 plusmn 090 150 plusmn 023 nsEvergreen Hardy White 041 plusmn 006 041 plusmn 001 ns 115 plusmn 056 091 plusmn 016 nsFeast 051 plusmn 016 065 plusmn 021 ns 214 plusmn 043 107 plusmn 063 P = 0031GA-C 76 049 plusmn 007 049 plusmn 010 ns 158 plusmn 018 093 plusmn 051 nsIshikura Improved F1 034 plusmn 003 040 plusmn 008 ns 169 plusmn 106 145 plusmn 070 nsImproved Beltsville Bunching 041 plusmn 003 041 plusmn 007 ns 104 plusmn 092 129 plusmn 050 nsJionji Negi 046 plusmn 007 035 plusmn 015 ns 185 plusmn 070 221 plusmn 050 nsLong White Bunching 052 plusmn 004 058 plusmn 017 ns 186 plusmn 006 225 plusmn 068 nsParade 045 plusmn 010 050 plusmn 024 ns 177 plusmn 033 216 plusmn 048 nsPerformer 066 plusmn 017 040 plusmn 002 ns 160 plusmn 011 207 plusmn 119 nsPesoenyj 044 plusmn 003 039 plusmn 001 P = 0022 140 plusmn 042 195 plusmn 080 nsShounan 042 plusmn 003 040 plusmn 003 ns 178 plusmn 052 108 plusmn 053 nsWhite Spear 050 plusmn 021 051 plusmn 022 ns 146 plusmn 042 108 plusmn 062 nsZhang Qui Da Cong 042 plusmn 005 041 plusmn 008 ns 111 plusmn 050 132 plusmn 046 ns274254-05GI 036 plusmn 006 040 plusmn 000 ns 180 plusmn 071 214 plusmn 081 nsG 30393-06GI 069 plusmn 020 055 plusmn 012 ns 184 plusmn 031 132 plusmn 064 nsLSD005

c 015 020 ns 096aComposition of 119899 = 6 plant samples from 4 replications plusmn standard deviation bSignificance based on paired Studentrsquos t-test among treatments ns notsignificant cLSD for differences between cultivar means 120572 = 005

(120573-carotene 120572-carotene and cryptoxanthins) support themaintenance of healthy epithelial cell differentiation normalreproductive performance and visual functions [26] Bothprovitamin A carotenoids and nonprovitamin A carotenoids(lutein zeaxanthin and lycopene) function as free radicalscavengers enhance the immune response suppress cancerdevelopment and protect eye tissues [27] Humans cannotsynthesize carotenoids and therefore must rely on dietarysources to provide sufficient levels Studies indicate that highintakes of a variety of vegetables providing a mixture ofcarotenoids weremore strongly associatedwith reduced can-cer and eye disease risk than intake of individual carotenoidsupplements [28] There is clear evidence that cultural prac-tices that maintain or enhance tissue carotenoid levels wouldbe beneficial to humans when regularly consumed in the diet

33 Shoot Tissue Chlorophyll Pigment Concentrations Nochlorophyll pigments were measured in the pseudostemtissues of any of the bunching onion cultigens (Figure 1data not shown) Chlorophyll 119886 responded significantly toUV radiation treatments (119865 = 435 119875 = 00398) butnot to cultigens or the interaction between treatment andcultigen ldquoFeastrdquo had the highest concentration of chloro-phyll 119886 at 5956mg100 g FM for cultigens grown undersupplemental UV-B radiation while ldquoDeep Purplerdquo had thelowest at 2775mg100 g FM For the cultigens grown withoutsupplemental UV-B radiation ldquoPesoenyjrdquo had the highestconcentration of chlorophyll 119886 at 6327mg100 g FM whileldquoEvergreenHardyWhiterdquo had the lowest at 1652mg100 g FM

(Table 5) Values for chlorophyll 119886 for cultigens are in closeagreement with Dissanayake et al [29] who reported valuesof sim7500mg chlorophyll a100 g FM for the A fistulosumcultigen ldquoKujyo-hosordquo

The bunching onions showed significant differences inchlorophyll 119887 caused by UV-B treatment (119865 = 1904 119875 lt00001) and cultigen (119865 = 208 119875 = 00179) but there wereno influences from their interaction Values for chlorophyll119887 for cultigens are in close agreement with Dissanayakeet al [29] who reported values of sim1700mg chlorophyllb100 g FM for the A fistulosum cultigen ldquoKujyo-hosordquoSignificant increases in chlorophyll 119887 in response to UV-Bradiation were found for cultigens ldquoFeastrdquo ldquoGA-C 76rdquo andldquoShounanrdquo (Table 5) The concentrations of chlorophyll 119887 forcultigens grown under supplemental UV-B radiation rangedfrom 2924mg100 g FM for ldquoGA-C 76rdquo to 1849mg100 gFM for ldquoImproved Beltsville Bunchingrdquo For cultigens grownwithout supplemental UV-B radiation chlorophyll 119887 concen-trations ranged from 2974mg100 g FM for ldquoPesoenyjrdquo to1578mg100 g FM for ldquoImproved Beltsville Bunchingrdquo

Concentrations of total chlorophyll (chlorophyll a + b)in bunching onions were found to differ between UV-Btreatments (119865 = 682 119875 = 00105) but not among cultigensldquoFeastrdquo and ldquoGA-C 76rdquo were the only bunching onion culti-gens to show differences between UV-B treatments (Table 5)Total chlorophyll concentrations ranged from 8882mg100 gFM for ldquoFeastrdquo to 4562mg100 g FM for ldquoZhang Qui DaCongrdquo for bunching onions grown under supplemental UV-B radiation For the plants grown without UV-B radiationranges from total chlorophyll varied from 9301mg100 g FM


Table 5 Mean valuesa for shoot tissue chlorophyll a chlorophyll b and total chlorophyll (chlorophyll a + chlorophyll b) (mg100 g freshmass) forAlliumfistulosumL cultigens grownunder supplementalUV-B (313 nm) light [70120583molsdotmminus2sdotsminus2 (268Wsdotmminus2) UV-B] orUV-filtered(control) light in a glasshouse in Knoxville TN USA (35∘961015840N Lat)

Cultigen Chlorophyll a Chlorophyll b Total chlorophyllUV-B Control Pr gt |119905|b UV-B Control Pr gt |119905| UV-B Control Pr gt |119905|

mg100 g fresh massDeep Purple 278 plusmn 221 253 plusmn 56 ns 206 plusmn 44 169 plusmn 24 ns 483 plusmn 256 421 plusmn 75 nsEvergreen Hardy White 314 plusmn 211 165 plusmn 32 ns 255 plusmn 51 182 plusmn 07 ns 569 plusmn 261 347 plusmn 35 nsFeast 596 plusmn 203 190 plusmn 105 P = 0012 273 plusmn 40 177 plusmn 19 P = 0005 868 plusmn 243 367 plusmn 110 P = 0009GA-C 76 470 plusmn 164 172 plusmn 106 ns 292 plusmn 71 181 plusmn 13 P = 0021 762 plusmn 233 354 plusmn 115 P = 0020Ishikura Improved F1 499 plusmn 536 231 plusmn 59 ns 256 plusmn 116 176 plusmn 47 ns 745 plusmn 651 407 plusmn 26 nsImproved Beltsville Bunching 239 plusmn 284 206 plusmn 89 ns 185 plusmn 76 158 plusmn 10 ns 424 plusmn 360 361 plusmn 98 nsJionji Negi 483 plusmn 234 472 plusmn 189 ns 255 plusmn 31 209 plusmn 48 ns 738 plusmn 260 680 plusmn 234 nsLong White Bunching 369 plusmn 66 372 plusmn 74 ns 197 plusmn 28 171 plusmn 27 ns 565 plusmn 92 543 plusmn 63 nsParade 386 plusmn 132 444 plusmn 188 ns 212 plusmn 41 199 plusmn 44 ns 598 plusmn 172 643 plusmn 230 nsPerformer 368 plusmn 31 496 plusmn 319 ns 230 plusmn 21 209 plusmn 71 ns 598 plusmn 48 705 plusmn 389 nsPesoenyj 368 plusmn 102 633 plusmn 369 ns 263 plusmn 24 297 plusmn 87 ns 263 plusmn 24 930 plusmn 456 nsShounan 443 plusmn 249 206 plusmn 191 ns 243 plusmn 83 166 plusmn 76 ns 686 plusmn 326 372 plusmn 267 nsWhite Spear 304 plusmn 99 182 plusmn 96 ns 208 plusmn 19 178 plusmn 10 P = 0033 512 plusmn 107 354 plusmn 89 nsZhang Qui Da Cong 253 plusmn 183 273 plusmn 135 ns 204 plusmn 74 193 plusmn 42 ns 456 plusmn 256 471 plusmn 176 ns274254-05GI 366 plusmn 231 400 plusmn 181 ns 189 plusmn 53 187 plusmn 49 ns 555 plusmn 283 586 plusmn 215 nsG 30393-06GI 398 plusmn 113 226 plusmn 138 ns 213 plusmn 41 170 plusmn 37 ns 611 plusmn 151 396 plusmn 160 nsLSD005

c ns 260 ns 68 ns 316aComposition of 119899 = 6 plant samples from 4 replications plusmn standard deviation bSignificance based on paired Studentrsquos t-test among treatments ns notsignificant cLSD for differences between cultivar means 120572 = 005

for ldquoPesoenyjrdquo to 3474mg100 g FM for ldquoEvergreen HardyWhiterdquo

The ratio of chlorophyll 119886 to chlorophyll 119887 in the bunchingonions showed significant changes based on cultigen (119865 =226 119875 = 00094) but not for UV-B radiation treatmentsIn general cultigens were evenly divided in their responsesto UV-B radiation with half the cultigens displaying higherchlorophyll achlorophyll 119887 under the supplemental UV-Bradiation treatment (Table 4) However only the cultigenldquoFeastrdquo had a significantly higher chlorophyll achlorophyll119887 ratio under UV-B radiation ldquoLong White Bunchingrdquo hadthe highest chlorophyll achlorophyll 119887 ratio in the bunchingonions grown without supplemental UV-B at 225 and ldquoGA-C 76rdquo had the lowest ratio at 091 Under UV-B radiationtreatment ldquoFeastrdquo has the highest chlorophyll achlorophyll119887 ratio at 214 while ldquoImproved Beltsville Bunchingrdquo has thelowest ratio at 104

34 Shoot Tissue Photochemical Efficiency (119865V119865119898) Photo-chemical efficiency (119865V119865119898) showed significant differencesbetween UV treatments (119865 = 1389 119875 = 00003) and cultigen(119865 = 211 119875 = 00152) but no difference due to treatmentand cultigen interaction (data not shown) Values for 119865V119865119898for all of the cultigens evaluated in the study averaged 082One previous study by Tsormpatsidis et al [30] showed thatwhile ldquoLollo Rossordquo lettuce (Lactuca sativa L) had decreasedvegetative growth under UV light treatments there was no

difference in photochemical efficiency By contrast whenthe agronomic crop wheat was exposed to UV radiationdecreases in 119865V119865119898 occurred under the UV light treatment[31] None of the cultigens in this study showed differences in119865V119865119898 however most of the cultigens differed in shoot tissuefresh biomass when exposed to UV-B radiation

4 Conclusion

Data from multiple studies demonstrates cultigens withina given plant species can react differently under variablestress conditions Most often harsh stress conditions nega-tively impact plant biomass In the current study decreasesin bunching onion shoot tissue biomass confirmed that aradiational stress from theUV-B treatment had occurredThebunching onion cultigens demonstrated genetic variabilityin response to UV-B radiation (Tables 1ndash5) Changes inplant pigments associated with light harvesting and photo-protection can be expected when bunching onion cultigensexperience greater levels of UV-B radiation in the growingenvironment In the current study the cultigens with thegreatest stimulation in carotenoid pigments from UV-Bexposure were ldquoFeastrdquo and the accession G 30393-06GI Datapresented here may be valuable to improve abiotic stresstolerance to increasing UV-B radiation for specialty cropbreeding programs


Conflict of Interests

Theauthors of the paper do not have a direct financial relationwith the commercial identities mentioned in the paper thatmight lead to conflict of interests

Acknowledgments

Mention of trade names or commercial products in this publi-cation is solely for the purpose of providing specific informa-tion and does not imply recommendation or endorsement bythe University of Tennessee Institute of Agriculture Authorswould like to acknowledge funding and support for thiswork by theUniversity of Tennessee Agricultural ExperimentStation

References

[1] G Sandmann ldquoGenetic manipulation of carotenoid biosyn-thesis strategies problems and achievementsrdquo Trends in PlantScience vol 6 no 1 pp 14ndash17 2001

[2] J T Landrum and R A Bone ldquoLutein zeaxanthin and themacular pigmentrdquo Archives of Biochemistry and Biophysics vol385 no 1 pp 28ndash40 2001

[3] M G Ferruzzi and J Blakeslee ldquoDigestion absorption andcancer preventative activity of dietary chlorophyll derivativesrdquoNutrition Research vol 27 no 1 pp 1ndash12 2007

[4] Y Endo R Usuki and T Kaneda ldquoAntioxidant effects ofchlorophyll and pheophytin on the autoxidation of oils in thedark IIThemechanism of antioxidative action of chlorophyllrdquoJournal of the American Oil Chemistsrsquo Society vol 62 no 9 pp1387ndash1390 1985

[5] D A Kopsell C E Sams D E Deyton K R Abney D EKopsell and L Robertson ldquoCharacterization of nutritionallyimportant carotenoids in bunching onionrdquoHortScience vol 45no 3 pp 463ndash465 2010

[6] K A Steinmetz and J D Potter ldquoVegetables fruit and cancerII Mechanismsrdquo Cancer Causes and Control vol 2 no 6 pp427ndash442 1991

[7] B Demmig-Adams A M Gilmore and W W Adams IIIldquoIn vivo functions of carotenoids in higher plantsrdquo The FASEBJournal vol 10 no 4 pp 403ndash412 1996

[8] R Croce SWeiss andR Bassi ldquoCarotenoid-binding sites of themajor light-harvesting complex II of higher plantsrdquoThe Journalof Biological Chemistry vol 274 no 42 pp 29613ndash29623 1999

[9] J A Mares-Perlman A E Millen T L Ficek and S EHankinson ldquoThe body of evidence to support a protectiverole for lutein and zeaxanthin in delaying chronic diseaseOverviewrdquo Journal of Nutrition vol 132 no 3 pp 517Sndash524S2002

[10] G J F MacDonald Ed Biological Impacts of Increased Intensi-ties of Solar Ultraviolet Radiationedition National Academy ofSciences Washington DC USA 1st edition 1973

[11] L Yuan Z Yanqun C Haiyan C Jianjun Y Jilong and HZhide ldquoIntraspecific responses in crop growth and yield of 20wheat cultivars to enhanced ultraviolet-B radiation under fieldconditionsrdquo Field Crops Research vol 67 no 1 pp 25ndash33 2000

[12] M Caasi-Lit M I Whitecross M Nayudu and G J TannerldquoUV-B irradiation induces differential leaf damage ultrastruc-tural changes and accumulation of specific phenolic com-pounds in rice cultivarsrdquoAustralian Journal of Plant Physiologyvol 24 no 3 pp 261ndash274 1997

[13] M Saile-Mark and M Tevini ldquoEffects of solar UV-B radiationon growth flowering and yield of Central and Southern Euro-pean bush bean cultivars (Phaseolus vulgaris L)rdquo Plant Ecologyvol 128 no 1-2 pp 114ndash125 1997

[14] D Giuntini G Graziani B Lercari V Fogliano G F Soldatiniand A Ranieri ldquoChanges in carotenoid and ascorbic acidcontents in fruits of different tomato genotypes related to thedepletion of UV-B radiationrdquo Journal of Agricultural and FoodChemistry vol 53 no 8 pp 3174ndash3181 2005

[15] M Marotti and R Piccaglia ldquoCharacterization of flavonoids indifferent cultivars of onion (Allium cepa L)rdquo Journal of FoodScience vol 67 no 3 pp 1229ndash1232 2002

[16] D A Kopsell and W M Randle ldquoSelenium affects the S-alk(en)yl cysteine sulfoxides among short-day onion cultivarsrdquoJournal of the American Society for Horticultural Science vol124 no 3 pp 307ndash311 1999

[17] M Takahashi and T Shibamoto ldquoChemical compositionsand antioxidantanti-inflammatory activities of steam distillatefrom freeze-dried onion (Allium cepa L) sproutrdquo Journal ofAgricultural and Food Chemistry vol 56 no 22 pp 10462ndash10467 2008

[18] A Denny and J Buttriss Synthesis Report no 4 Plant Foodsand Health Focus on Plant Bioactive European Food Informa-tion Resource (EuroFIR) Consortium EuroFIR ProjectBritishNutrition Foundation Institute of Food Research NorwichUK 2007

[19] D R Hoagland and D I Arnon ldquoThe water culture method forgrowing plants without soilrdquoCalifornia Agricultural ExperimentStation Circular vol 347 pp 4ndash32 1950

[20] DAKopsell D E KopsellMG Lefsrud J Curran-Celentanoand L E Dukach ldquoVariation in lutein 120573-carotene and chloro-phyll concentrations among Brassica oleracea cultigens andseasonsrdquo HortScience vol 39 no 2 pp 361ndash364 2004

[21] B H Davies and H P Kost ldquoChromatographic methods forthe separation on carotenoidsrdquo in Plant Pigments Fat SolublePigments H P Kost G Zweig and J Sherma Eds vol 1 ofHandbook of Chromatography pp 1ndash85 CRCPress Boca RatonFla USA 1988

[22] V G Kakani K R Reddy D Zhao and K Sailaja ldquoField cropresponses to ultraviolet-B radiation a reviewrdquo Agricultural andForest Meteorology vol 120 no 1ndash4 pp 191ndash218 2003

[23] US Department of Agriculture USDA National NutrientDatabase for Standard Release SR25 httpndbnalusdagov

[24] M Umehara T Sueyoshi K Shimomura et al ldquoInterspecifichybrids betweenAlliumfistulosum andAllium schoenoprasum-reveal carotene-rich phenotyperdquo Euphytica vol 148 no 3 pp295ndash301 2006

[25] K K Niyogi A R Grossman and O Bjorkman ldquoArabidopsismutants define a central role for the xanthophyll cycle in theregulation of photosynthetic energy conversionrdquo Plant Cell vol10 no 7 pp 1121ndash1134 1998

[26] G F Combs ldquoVitamin Ardquo in The Vitamins FundamentalAspects in Nutrition and Health pp 107ndash153 Academic PressSan Diego Calif USA 2nd edition 1998

[27] K J Yeum and R M Russell ldquoCarotenoid bioavailability andbioconversionrdquo Annual Review of Nutrition vol 22 pp 483ndash504 2002


[28] E J Johnson B RHammondK J Yeumet al ldquoRelation amongserum and tissue concentrations of lutein and zeaxanthinand macular pigment densityrdquo American Journal of ClinicalNutrition vol 71 no 6 pp 1555ndash1562 2000

[29] P K Dissanayake N Yamauchi and M Shigyo ldquoChloro-phyll degradation and resulting catabolite formation in storedJapanese bunching onion (Allium fistulosum L)rdquo Journal of theScience of Food and Agriculture vol 88 no 11 pp 1981ndash19862008

[30] E Tsormpatsidis R G C Henbest F J Davis N H Battey PHadley and A Wagstaffe ldquoUV irradiance as a major influenceon growth development and secondary products of commer-cial importance in Lollo Rosso lettuce ldquoRevolutionrdquo grownunder polyethylene filmsrdquo Environmental and ExperimentalBotany vol 63 no 1ndash3 pp 232ndash239 2008

[31] X C Lizana S Hess and D F Calderini ldquoCrop phenologymodifies wheat responses to increased UV-B radiationrdquo Agri-cultural and Forest Meteorology vol 149 no 11 pp 1964ndash19742009

Submit your manuscripts athttpwwwhindawicom

Nutrition and Metabolism

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Food ScienceInternational Journal of

Agronomy


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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

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Applied ampEnvironmentalSoil Science

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AgricultureAdvances in


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GenomicsInternational Journal of


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and dissipating excess thermal energy [7 8]The xanthophyllcycle or violaxanthin cycle is the mechanism by whichplants regulate light energy available for photosynthesis Inintense light situations violaxanthin is rapidly and reversiblyconverted to zeaxanthin via antheraxanthin Zeaxanthin is adirect quencher of chlorophyll excited states and can preventphotooxidative stress and lipid peroxidation [7]

Higher amounts of UV-A (380ndash320 nm) and UV-Bradiation (280ndash320 nm) may influence the accumulation ofplant compounds used to combat light stress Carotenoidmetabolites not only protect plants from excess UV radiationbut also can protect humans from UV radiation whentranslocated to subdermal skin tissues [9] What remainsuncertain is the impact of increased UV radiation on growthand development and nutritional values of cultivated crops[10] Previous studies have demonstrated impacts of UVradiation on plant performance cellular structures andpigment accumulations In a study by Yuan et al [11] 20cultivars of wheat (Triticum aestivum L) were grown underUV-B radiation stress to determine possible detrimentalinfluencesMost wheat cultivars responded negatively to UV-B radiation however several cultivars showed increases inplant height and biomass Structural changes like rupturedchloroplast envelopes have been noted in UV-sensitive ricecultivars (Oryza sativa L) when exposed to UV stress [12]Increases in UV radiation can delay flowering and harvesttimes among different cultigens of bush beans (Phaseolusvulgaris L) [13] Bush beans grown under UV radiationshowed decreases in fruit size and yield when compared tocultivars not grown under UV radiation stress Tomatoes(Solanum lycopersicum cv DRW 5981) grown using UV-Bblocking filters showed increases in lycopene and 120573-carotenewhile fruits of the same variety showed decreases in lycopenephytoene and phytofluene when grownwithout UV-B block-ing filters [14] The tomato cultivar ldquoHP1rdquo accumulated morethan twice the amount of lycopene in fruit tissues whengrown under no UV-B radiation Results from such studiesdemonstrate impacts on nutritional quality from excess UVradiation

Allium species are valued worldwide for culinary fla-vor and medicinal attributes Plants in this genus havebeen important to multiple cultures for centuries Alliumshave high levels of nutritionally important secondary plantmetabolites which convey numerous health benefits Forexample bulb onions (Allium cepa L) contain high levels offlavonoids [15] S-alk(en)yl-L-cysteine sulfoxides [16] and avariety of volatile antioxidant compounds [17] However nostudies to date have measured the impact of UV radiationon the production of nutritionally important pigments inAlliums Allium fistulosum is consumed in part for its shoottissues as well as pseudostems Carotenoid and chlorophyllcompounds are present in the shoot tissues ofAfistulosum [518] Therefore the objectives of this project were to examineboth environmental and genetic responses to elevated UV-B radiation among a large subset of A fistulosum cultigensResponses were noted for plant height shoot tissue biomassphotochemical efficiency (119865V119865119898) and concentrations ofcarotenoid and chlorophyll pigments in the shoot and pseu-dostem tissues

2 Methods and Materials

21 Plant Culture On December 16 2008 seeds of 16different A fistulosum cultigens were sown in 15 cm potsholding soilless media in a glasshouse in Knoxville TNUSA (35∘961015840N Lat) which blocked UV-wavelengths (280ndash380 nm)Thephotosynthetically active radiation (PAR) in theglasshouse averaged 540 120583molsdotmminus2sdotsminus2 (Apogee Nanologgermodel ANL Apogee Instruments Inc Roseville CA USA)The cultigens included eight accessions [PI 274254-05GIPI 462345-05GI (Jionji Negi) PI 546343-90U01 (GA-C 76)PI 546228-06GI (Improved Beltsville Bunching) PI 280562-04GI (Pesoenyj) PI 436539-06GI (Zhang Qui Da Cong)PI 462357-06GI (Shounan) and G 30393-06GI] from theUSDA-ARS National Plant Germplasm Repository (GenevaNY USA) four cultivars (ldquoLong White Bunchingrdquo ldquoFeastPerformerrdquo and ldquoParaderdquo) from Seedway LLC (Hall NYUSA) and four cultivars (ldquoWhite Spearrdquo ldquoEvergreen HardyWhiterdquo ldquoDeep Purplerdquo and ldquoIshikura Improved F1rdquo) fromJohnnyrsquos Selected Seeds (Winslow ME USA) The seedlingswere watered daily for the duration of the experiment OnJanuary 10 2009 the seedlings were thinned to two plantsper pot and fertilized with a nutrient solution containing(mgsdotLminus1) N (105) P (915) K (1173) Ca (802) Mg (246) S(320) Fe (05) B (025) Mo (0005) Cu (001) Mn (025)and Zn (0025) [19] Each pot was fertilized once a weekfor the duration of the experiment with 100mL of nutrientsolution The experimental design was a split plot arrangedas a randomized complete block UV-B treatments were themain plots and A fistulosum cultigens were the subplots Sixindividual plants per cultigen composed a replication withfour replications randomly assigned to each UV-B treatment

Supplemental UV-B radiation (313 nm) was provided bybanks of commercially available UV-B 313 lamps (Q-PanelLab Products Cleveland OH USA) and treatment beganon January 27 2009 delivering 70120583molsdotmminus2sdotsminus2 (268Wsdotmminus2)of UV-B (Spectroradiometer Model SPEC-UVPAR ApogeeInstruments Inc Roseville CA USA) to the treated plantsTo control pests in the greenhouse the beneficial insectspecies of Hypoaspis miles and Neoseiulus cucumeris wereused to control thrips whileOrius insidiosuswas used to helpcontrol aphidsThese insectswere first released on January 232009 and were released every two weeks thereafter

On March 3 2009 all of the bunching onion culti-gens were harvested Six plants were harvested from eachreplication Fresh weights and plant heights were taken andaveraged for each replication One measure of 119865V119865119898 wastaken from each of the harvest plants at the midpoint of plantheight using a modulated fluorometer (OS1-F1 ModulatedFluorometer Opti-Sciences Hudson NH USA) The 119865V119865119898value is an indication of photoinhibition and overall planthealth All plants were harvested and pseudostem and leaftissue were separated The samples were immediately placedin a minus20∘C freezer before being moved to a minus80∘C freezerwithin 8 h

22 Pigment Extraction and Determination Tissue pigmentswere extracted according to Kopsell et al [20] and analyzed



2






96

5

4

32

8

1

10 20 30 40 50

40

05101520253035

7

(min)

(mAU

)

(a)

2

15

1

05

0

minus05

minus1

8

10 20 30 40 50(min)

(mAU

)

(b)































LSD005



































4 Conclusion





Acknowledgments


References



































Journal of




Agronomy





Microbiology




Volume 2014


























2






96

5

4

32

8

1

10 20 30 40 50

40

05101520253035

7

(min)

(mAU

)

(a)

2

15

1

05

0

minus05

minus1

8

10 20 30 40 50(min)

(mAU

)

(b)































LSD005



































4 Conclusion





Acknowledgments


References



































Journal of




Agronomy





Microbiology




Volume 2014


















































LSD005



































4 Conclusion





Acknowledgments


References



































Journal of




Agronomy





Microbiology




Volume 2014





















































4 Conclusion





Acknowledgments


References



































Journal of




Agronomy





Microbiology




Volume 2014



























Acknowledgments


References



































Journal of




Agronomy





Microbiology




Volume 2014































Journal of




Agronomy





Microbiology




Volume 2014
























Research Article UV-B Radiation Impacts Shoot Tissue Pigment Composition...

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Transcript of Research Article UV-B Radiation Impacts Shoot Tissue Pigment Composition...