Characteristics of Photosystem II Behavior in Cotton (Gossypium hirsutum L.) Bract and Capsule Wall

Journal of Integrative Agriculture2013, 12(11): 2056-2064 November 2013

© 2013, CAAS. All rights reserved. Published by Elsevier Ltd. Doi:10.1016/S2095-3119(13)60343-3

RESEARCH ARTICLE

Characteristics of Photosystem II Behavior in Cotton (Gossypium hirsutum L.) Bract and Capsule Wall

ZHANG Ya-li1, LUO Hong-hai1, HU Yuan-yuan1, Reto J Strasser2, 3, 4 and ZHANG Wang-feng1

1 Key Laboratory of Oasis Eco-Agriculture, Xinjiang Production and Construction Group/Agricultural College, Shihezi University, Shihezi 832003, P.R.China

2 Bioenergetics Laboratory, University of Geneva, Jussy-Geneva CH-1254, Witzerland3 Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095, P.R.China4 North West University, Campus Pochefstroom 2520, South Africa

Abstract

Though bract and capsule wall of boll in cotton (Gossypium hirsutum L.) have different photosynthetic capacities, the features of photosystem II (PS II) in these organs are scarce. In this paper, chlorophyll a fl uorescence emission was measured to investigate the difference in the photosynthetic apparatus of dark-acclimated (JIP-test) and light-acclimated (light-saturation pulse method) bract and capsule wall. Compared with leaves, the oxygen evolving system of non-foliar organs had lower effi ciency. The pool size of PS II electron acceptor of non-foliar organs was small, and the photochemical activity of leaves was higher than that of the bract and capsule wall. In regard to the photosystem I (PS I) electron acceptor side, the pool size of end electron acceptors of leaves was larger, and the quantum yield of electron transport from QA (PS II primary plastoquinone acceptor) further than the PS I electron acceptors of leaves was higher than that of bract and capsule wall. In all green organs, the actual quantum yield of photochemistry decreased with light. The thermal dissipation fraction of light absorbed by the PS II antennae was the highest in bract and the lowest in capsule wall relative to leaves. Compared with leaves, capsule wall was characterized by less constitutive thermal dissipation and via dissipation as fl uorescence emission. These results suggested that lower PS II photochemical activity in non-foliar organs may be result from limitations at the donor side of PS II and the acceptor sides of both photosystems.

Key words: cotton, non-foliar, photosynthesis, chlorophyll fl uorescence, JIP-test

INTRODUCTION

In cotton, the leaves, bracts and capsule walls of boll have physiologically functions such as photosynthesis, respiration and transpiration (Constable and Rawson 1980; Wullschleger and Oosterhuis 1990a, 1991; Wullschleger et al. 1991). Generally, leaf commonly is considered as the primary sources of photosynthate production. Actually, bracts and capsule walls of boll in cotton plants can perform photosynthetic CO2 as-

similation (Wullschleger and Oosterhuis 1990a, 1991; Wullschleger et al. 1991). Furthermore, there is evi-dence that the bracts and capsule walls would partially pay for their own carbon demands and as important organs contributing to the growth, development of the boll (Elomre 1973; Wullschleger and Oosterhuis 1990b; Wullschleger et al. 1991). Especially at late growth stage, the photosynthetic capacity of bolls (bracts plus capsule walls) to whole plant was about 23.7% when leaves began senesce (Hu et al. 2012).

The leaves, however, are more physiologically

Received 23 October, 2012 Accepted 17 December, 2012Correspondence ZHANG Wang-feng, Tel: +86-993-2057326, Fax: +86-993-2057999, E-mail: [email protected]

Characteristics of Photosystem II Behavior in Cotton (Gossypium hirsutum L.) Bract and Capsule Wall 2057

© 2013, CAAS. All rights reserved. Published by Elsevier Ltd.

active, with greater values for photosynthesis and res-piration than the bracts and capsule walls (Wullschleger and Oosterhuis 1990a; Wullschleger et al. 1991). Some reports (Bondada et al. 1994; Bondada and Oosterhuis 2000) suggested that the photosynthetic disparities re-sulted from the anatomical and epidermal characteris-tics of those organs. However, the disparity in photo-synthesis between those organs may be also related to their characteristics of photosystem II (PS II, Kalach-anis and Manetas 2010). Little information is known with respect to these characteristics of the non-foliar organs in cotton till present.

Chlorophyll a fl uorescence signals can be analyzed to provide detailed information about the structure, conformation and function of PS II (Strasser and Sironval 1972, 1973; Strasser 1978; Krause and Weis 1991). Chlorophyll a fl uorescence technique has been proven to be a very useful tool for the analysis of differences in the photosynthetic activity and, further-more, allows testing any type of chlorophyll contain-ing samples in any form. In vivo, in situ measurements allow in some cases to estimate chemical properties on the molecular level as well as the comparison of struc-tural parameters such as the ratio of photochemical and non-photochemical rate constants kP/kN. Based on the energy flux theory in Biomembranes (Strasser 1978, 1981), an analysis of the OJIP fluorescence transient, termed as the JIP-test, has been developed by Strass-er (Strasser and Strasser 1995; Strasser et al. 2000, 2004), by which PS II structural, conformational and functional parameters are derived. The ultimate aim of this study is to delineate differences in structure, conformation and function of PS II of the bract and capsule wall. With that aim, chlorophyll fl uorescence parameters are monitored in dark-acclimated (JIP-test) and light-acclimated (light-saturation pulse method) non-foliar organs. Such information not only is useful in understanding the photosynthetic disparities of these tissues but also has great benefi t for understanding the non-foliar photosynthesis in plants.

RESULTS

Chlorophyll a fluorescence induction curve FO-FK-FJ-FI-FP

The chl. a fluorescence transients of dark-adapted

leaves, bracts and capsule walls of cotton plants were presented in Fig. 1. Each transient, plotted on loga-rithmic time scale from 20 μs to 1 s, was the average of all raw fl uorescence transients.

As shown in Fig. 1, all three transients demonstrate typical polyphasic rise called in alphabetical order from FP to FO as O-K-J-I-P fluorescence transient. Each letter stands for a time spaced by a factor approx-imately of 10 to the next letter. Typically O-K-J-I-P corresponds to the time marks of about 0.03, 0.3, 3.0, 30, and 300 ms. Differences were observed among the three transients. The differences were clearly when suitable normalizations and subtractions are performed and/or when the transients are translated by the JIP-test equations to biophysical parameters that can be then quantitatively compared.

Normalization of chl. a fl uorescence transients

Fig. 2 presented the chl. a fl uorescence kinetics Ft of Fig. 1 as kinetics of the relative variable fl uorescence Vt (left vertical axis): (a) between Fo and FM: VOP (t)=(Ft-Fo)/(FM-Fo); (b) between Fo and FJ: VOJ (t)=(Ft-Fo)/(FJ-Fo); (c) between Fo and F300 μs: VOK (t)=(Ft-Fo)/(F300 μs-Fo); (d) between FI and FM: VIM (t)=(Ft-FI)/(FM-FI) and, in the insert, between Fo and FI , as VOI (t)=(Ft-Fo)/(FI-Fo). In each of the plot (a), (b) and (c), the difference kinet-ics, Vxy, were also presented (right vertical axis); the Vxy kinetics result (as indicated) by subtracting the

Fig. 1 Chl. a fl uorescence transients (OJIP) of dark-adapted leaves, bracts and capsule walls of cotton plants. Each transient, plotted on a logarithmic time scale from 20 μs to 1 s, is induced by red actinic light (650 nm; 3 500 μmol photons m-2 s-1; Handy PEA fl uorimeter).

2058 ZHANG Ya-li et al.


relative variable fl uorescence kinetics of the leaf (L) from each of the three relative variable fluorescence kinetics (hence denoted in the Fig. 2 as L-L, B-L and C-L, where B and C represent bract and capsule wall, respectively).

From Fig. 2-A, we observed from the different ki-netics of two positive bands, one in the range from 20 μs to 20 ms (O-I part of the transient), which had its maximal amplitudes at the J-step (2 ms), and an-other one in the range from 20 to 200 ms (I-P part of the transient). The O-I and I-P bands of the difference kinetics DVOM=[(Ft-Fo)/(FM-Fo)] between leaf and bract were both more pronounced than that between leaf and capsule wall. And the maximal amplitude of the O-I band at the J-step was higher in the bract. Concerning the difference on the O-J phase of the transient, we ob-served in Fig. 2-B two positive K-bands in the differ-ent kinetics VOJ. The K-bands appeared at the same fl uorescence transient (JIP-time) time, at 300 μs, for both the bract and the capsule wall, while the ampli-tude for the former was bigger than that for the latter.

The plot of Fig. 2-C presented the difference kinet-ics in the 20-300 μs time range, VOK. For the bract, we observed a positive L-band, at about 170 μs. Also, for the capsule wall, there was a positive L-band, but the amplitude was smaller than that for bract. Fig. 2-D presented two different normalization of the I-P phase of the transients. With the normalization employed for the plot in the insert, the differences among the three tissues concerning the relative amplitude of the I-P phase, (Ft-Fo)/(FI-Fo), were depicted. We observed that this amplitude were higher in the leaf, followed by the capsule wall and the bract. However, as clearly re-vealed from the main plot in Fig. 2-D, where the nor-malization was done between FI and FM, as VIM=(Ft-FI)/(FM-FI), the kinetics of the differing amplitudes was similar for all the three tissues.

PS II biophysical parameters derived by the JIP-test

Fig. 3 presented the fluxes of absorption (ABS),

Fig. 2 The Chl. a fl uorescence kinetics Ft of Fig. 1 are presented as kinetics of different expressions of relative variable fl uorescence. A, between Fo and FM: VOP (t)=(Ft-Fo)/(FM-Fo). B, between Fo and FJ: VOJ (t)=(Ft-Fo)/(FJ-Fo). C, between F0 and F300 μs: VOK (t)=(Ft-Fo)/(F300 μs-Fo). D, between FI and FM: VIM (t)=(Ft-FI)/(FM-FI) and, in the insert, between Fo and FI: (Ft-Fo)/(FI-Fo).



trapping (TR0), dissipation (DI0), electron transport between PS II and PS I (ET0), and the reduction of PS I end electron acceptors (RE0). The fluxes were expressed per absorption ABS (i.e., as quantum yields) and per reaction centre RC (specifi c fl uxes).

The maximum quantum yield of PS II primary photochemistry (TR0 per ABS, equal to FV/FM=1-Fo/Fm) in the leaf, bract and capsule wall was similar with the values of about 0.8 (Fig. 3). However, the difference of ET/ABS, the quantum yield for electron transport up to PQ, was observed among these issues. The ET/ABS of the leaf was higher, followed by the capsule wall and the bract. This was because of the decrease of the effi ciency, ET0/TR0= Eo, with which a trapped exciton can move an electron into the electron transport chain from QA

- to PQ. For the processes from exciton trapping to PQ reduction (O-I part), the fl uxes (TR0 and ET0, per RC) were higher in the bract, followed by the capsule wall and the leaf, due to the higher ABS/RC of the bract (Fig. 3).

the quantum yield referring to the electron fl ow from PQH2 to the PS I end electron acceptors (RE0 per RC and ABS) were lower in the bract, higher in the leaf. The parameter Sm=EC/RC (Sm), expressed the energy needed to close all reaction centers, i.e., represented the electron acceptor pool size of PS II that includes all electron carriers between water and NADPH (Strasser et al. 1995). The EC/RC was higher in leaf, followed by the capsule wall and the bract.

Photochemistry in the light-adapted state

The fate of absorbed light energy in all green organs was shown in Fig. 4. In all green organs, PS II=1-Fs´/Fm´ decreased with the increase of PAR, being the highest in leaves, intermediate in capsule walls, and the lowest in bracts. NPQ=(Fs´/Fm´)-(Fs´/Fm) increased with PAR in a curvelinear manner. NPQ was the highest in bracts and the lowest in the capsule walls.

f, D=Fs´/Fm increased marginally at intermediate light in all green organs of cotton, and was the highest in capsule walls.

DISCUSSION

Wullschleger and Oosterhuis (1990a, 1991) have shown that the leaves possessed higher photosyn-thetic activity determined by gas exchange and 14C techniques compared to the bracts and capsule walls of boll. In this study, photosynthetic activities of dif-ferent chlorophyll-containing organs of cotton plants were investigated using chlorophyll fluorescence techniques including fast chl. a fl uorescence transients and saturation pulse method. The maximum quantum yield of PS II primary photochemistry (TR0/ABS=FV/FM=1-Fo/Fm) was similar among these tissues, indicat-ing that all of the green tissues measured have a maximal similar efficiency of primary light utilization in PS II. High effi ciency of exciton trapping indicates that pri-mary photochemistry is not limiting, yet limitations in further steps of the excitation energy processing and its transformation to redox energy and electron transport may be hidden behind a high TRo/ABS (Strasser et al. 2004; Zeliou et al. 2009). From Fig. 2-A, which demonstrated the difference of intersystem electron transport chain, we observed that the bract and the

Fig. 3 The parameters, derived by the JIP-test from the fast rise (OJIP) transients of dark-adapted leaves, bracts and capsule walls of cotton plants, were normalized using as reference the corresponding values from leaves.

The quantum yield of dissipation (DI0 per ABS) and the specifi c dissipation DI0/RC was lower in the leaf, and higher in the bract. Whereas, the fl uxes and



capsule wall both showed the O-I and I-P bands, while the amplitudes of both bands were higher in the bract. The O-I band of the VOI (t) kinetics revealed the pro-cesses from exciton trapping to PQ reduction, while the I-P band revealed the electron fl ow from PQH2 to the reduction of PS I end electron acceptors (Strasser et al. 2004, 2007; Schansker et al. 2005). From Fig. 3, we observed that the specific energy fluxes TRo/RC

and ET0/RC corresponding to the processes from exci-ton trapping to PQ reduction (refl ected in the O-I part of the OJIP transients) were lower in the leaf. On the other hand, the specifi c energy fl ux (RE0/RC) and the quantum yield (RE0/ABS) referring to the electron fl ow from PQH2 to the PS I end electron acceptors (refl ected in the I-P part of the OJIP transients) were higher in the leaf. In addition, Fig. 3 demonstrated that the elec-tron acceptor pool size of PS II (EC/RC) was higher in leaf, followed by capsule wall and bract. Thus, we could deduce that the process from exciton trapping to PQ reduction and from PQH2 to PS I end-electron acceptors was inefficient in non-foliar organs. Fur-thermore, the maximal amplitude of the O-I band at the J-step was higher in the bract. This indicates that bract has poor probability of energy conservation of the excitation energy trapped by the reaction centre and lower effi ciency of the electron transport after QA

- (Tsimilli-Michael and Strasser 2008). Additional, the appearance of O-I band may result from an elevated K-step which indicated the activity of non water electron donors to PS II (Fig. 2-B). A positive K-band refl ected an electron donation from internal electron donors, competing with the oxygen evolving system (Strasser et al. 2004, 2007). This happens under environmental stress, especially heat stress and water stress. In this investigation, stress was completely avoided at the pe-riod of sampling. Therefore, we assume that the lower inactivation of OEC might be an intrinsic character of non-foliar organs, which use more available reduced compounds (e.g., DH-ascorbate) as electron donors.

The L-band revealed differences of the energetic connectivity among PS II units (Strasser et al. 2004, 2007). Fig. 3-C showed that non-foliar organs of cotton had lower energetic connectivity among PS II units. Higher energetic connectivity in the photo-synthetic machinery leads to a better utilization of the excitation energy and was also a criterium for the stability of a photosynthetic system (Strasser 1978; Strasser et al. 2004). Therefore, we can reasonably predict that non-foliar organs had poor efficiency of utilization of excitation energy and instability of the photosynthetic systems. The processes from PQH2

to PS I end acceptors were different among the leaf, capsule wall and bract (Fig. 3-A and D); the pool of PS I end electron acceptors of the bract was smaller compared with leaf (insert of Fig. 3-D). However,

Fig. 4 Estimated fraction of absorbed irradiance consumed via PS II photochemistry ( PS II=1-Fs´/Fm´), pH- and xanthophyll-regulated thermal dissipation ( NPQ=(Fs´/Fm´)-(Fs´/Fm)), and the sum of fluorescence and light-independent constitutive thermal dissipation ( f, D= Fs´/Fm), in leaf, bract and capsule wall of cotton. Dotted line represents half rise PPFD position of the PS II curve.



there was no signifi cant difference among all the three cases on the conformation of the electron transfer pathway, i.e., the Michaelis-Menten constants KM of the electron transfer pathway from PQH2 to NADPH (Fig. 3-D). These fi ndings and interpretation were ver-ified and also quantified by the JIP-test application, which showed a clear distinction between the parame-ters, RE0/ABS, the quantum yield of electron transport from QA

- to the PS I electron acceptors. Based on above information, we wonded whether

the limitations observed in dark-adapted non-foliar organs would affect electron flow behaviour in the light-adapted state. Therefore, the saturation pulse method was used to study the energy flux under light-adapted state. There are three main pathways of allocation of photons absorbed by the PS II antennae: photochemical conversion, light-regulated non-pho-tochemical energy dissipation, and light-independent constitutive non-photochemical energy dissipation (Hendrickson et al. 2004). As shown in Fig. 4, the non-foliar organs had lower actual quantum yield of PS II in the light adapted state ( PS II) than leaves. Similar results were reported in tomato (Lycopersicon esculentum Mill.) by Hetherington et al. (1998) and in hellebore (Helleborus viridis L. agg.) by Aschan et al. (2005). Lower quantum yield of PS II in non-fo-liar organs may be related with both lower quantum yield of electron transport from trapped exciton to PS I electron acceptors and smaller electron acceptor pool size of PS II (Figs. 3 and 4). Bracts had lower PS II=1-Fs´/Fm´ and higher NPQ=(Fs´/Fm´)-(Fs´/Fm) indicating an excess of light energy absorbed by PS II. Thus, thermal dissipation of absorbed light via pH- and xanthophyll-mediated non-photochemical quenching was the dominant photoprotective mechanism in bracts to alleviate the damage of photoinhibition. Concern-ing the quantum yield of non-regulated energy loss by constitutive thermal dissipation and via fl uorescence,

f, D=Fs´/Fm was signifi cantly higher in capsule walls at all PPFD levels (Fig. 4), indicating the vulnerability of photoinhibition in capsule walls (Hendrickson et al. 2004). This may be because there was less thylakoid stacking in capsule walls chloroplasts (Bondada and Oosterhuis 2003), which allowed greater proximity of the two photosystems and consequently enhanced spillover of excitation energy from PS II to PS I (Kim et al. 2009). We are presenting here the mod-

ulated fluorescence expressions, which are derived from the signals Fm, Fm´ and Fs´ as commonly used and presented in the literature. However, we are ful-ly awared that the three experimental signals Fm per sample in the dark, Fm´ and Fs´ as sample in the light adapted state are three independent free information. However as ratios these three experimental signals represent only two free and independent parameters, because one expression can be derived from the two others. We are awared that the few conclusions de-rived from the modulated fl uorescence signals have to be considered only as “good guesses” as long as the changes in absorption and cross-section properties are unknown. This uncertainity for the assumptions that the absorptions ABS=ABS´ and the sample cross sec-tions CS=CS0´. This uncertainity can be checked by the JIP-test parameters. If the calculated parameters assume ABS/CS0=Fo and ABS/CSm=Fm exhibit similar trends (e.g., no antiparallelism) then we can assume that the interpretation given for the experimental data are correct trends with an uncertainity factor of (ABS´/CS´0)/(ABS/CS0) or (ABS´/CSm´)/(ABS/CSm). New developments of fast multichannel instruments, such as mPEA built by Hansatech Instruments GB offer the possibility to estimate the light absorption terms per sample cross section under all experimental conditions, e.g., dark or light adapted samples. Such additional measurements offer the option to decrease heavily the need to make for technical reasons assumptions, which may not be valid for the plants.

In summary, the JIP test proved to be useful for revealing structural and functional attributes of PS II and PS I of different plant organs, which have chloro-plasts. The distinct photosynthetic activity between the leaf, bract and capsule wall have been related to differences in PS II and PS I features. Lower PS II photochemical activity in non-foliar organs may re-sult from the limitations at the donor side of PS II and the acceptor sides of both photosystems. Although we found the photosynthetic disparities between the leaves, bracts and capsule walls on the aspect of the PS II and PS I features, we suggested that further re-search is needed to elucidate the photosynthetic dis-parities on the aspect of the photosynthetic enzyme activities and the different life cycles due to different aging and senescence kinetics in leaves, bracts and capsule walls.



MATERIALS AND METHODS

Plant materials

The experiment was conducted at the experimental fi led at Shihezi Agricultural College, Xinjiang, China (45°19´N, 86°03´E) in 2008. Cotton (Gossypium hirsutum L. cv. Xinluzao 13) plants were grown under drip irrigated field condition. Seeds were sown at 10 cm intro-row spacing at the density of 2.4×104 plants ha-1. Two alternate unequal row spacings were adopted. Plastic mulching was used on alternate rows. Drip tapes with emitters were set under the mulch. N and P2O5 were applied at the rates of 240 kg N ha-1 and 172.5 kg P2O5 ha-1, respectively. The plot was drip irrigated and maintained well-watered throughout the grow-ing season. Pest and weed control was carried out according to the local standard practice. The experimental design was completely randomized with three replications.

Three cotton plants were collected from each replication. Leaf, bract and capsule wall of boll samples were collected for experimental measurements from a canopy of plants with expanded leaves, bracts, and bolls on each plant (Fig. 5).

was used to measure chlorophyll a fl uorescence induction kinetic curves. All the fl uorescence transients were recorded within a time scan from 30 μs to 1 s with a data acquisition rate of 105 readings s-1 for the fi rst 2 ms and of 103 s-1 after 2 ms. Prior to fl uorescence induction kinetic measurement, leaves, bracts and bolls were dark-adapted at least 30 min. When dark-adapted leaves, bracts and bolls were illuminat-ed with sufficiently strong red light (2 000 μmol photons s-1 m-2), florescence transient displayed a polyphasic rise with two intermediate inflections called J and I appearing between the O and the P levels. The two intermediate in-fl ections, called J and I, are more clearly revealed when the fl uorescence induction kinetics are plotted on a logarithmic time scale.

The JIP test

The recorded OJIP transients were analysed according to the JIP-test (Strasser et al. 2000, 2004), with the Biolyzer software (Laboratory of Bioenergetics, University of Gene-va, Switzerland, written by Ronaldo Maldonado according to the eqs. of the JIP-test). The following original data are utilised by the JIP-test: the maximal measured fl uorescence intensity, FP, equal here to FM since the excitation intensity is high enough to ensure the closure of all PS II RCs; the fl uorescence intensity at 30 ms, considered as the intensity Fo when all PS II RCs are open; the fl uorescence intensity at 300 ms (F300 μs) required for the calculation of the initial slope M0 (between 50 and 300 ms) of the relative vari-able fluorescence Vt=(Ft-Fo)/(FM-Fo) kinetics, M0=(dV/dt)0=(V300 ms -V50 μs)/250 ms; the fl uorescence intensities at 2 ms (J step; FJ) and at 30 ms (I-step; FI); the complemen-tary area (Area) above the fl uorescence curve (i.e., the area between the curve, the horizontal line F=FM and the vertical lines at t=30 ms and at Fmax about 0.3 s).

The parameters calculated by the JIP-test, all referring to the condition of the sample at time zero (onset of fl uores-cence induction) are:

(a) The fl ux ratios or yields, namely, the maximum quan-tum yield of primary photochemistry (TR0/ABS=Po=1-Fo/FM), the quantum yield of energy dissipation (DI0/ABS =(ABS-TR0)/ABS=1-Po), the efficiency ET0/TR0 = Eo=1-VJ) with which a trapped exciton can move an electron into the electron transport chain from QA to the plastoquinone pool (PQ), the quantum yield of electron transport from QA- to PQ (ET0/ABS=(TR0/ABS)(ET0/TR0)=Eo=Po× Eo), the effi ciency with which an electron can move from reduced plastoquinone (plastoquinol, PQH2) to the PS I end electron acceptors. RE0/ET0=Ro=(1-VI)/(1-VJ), the quantum yield of electron transport from QA

- to the PS I electron acceptors (RE0/ABS=Ro=Po× Eo×Ro) and the effi ciency with which a trapped exciton in PS II can move an electron into the electron transport chain from QA

- to the PS I end electron acceptors (RE0/TR0= Eo Ro).

Fig. 5 The photograph of leaf, bract and boll from cotton plant. Three different final functions of the photosynthetic apparatus for the optimization of the ripening of cotton seeds: A, bracts are for protection of the bolls and for supplementary specific nutrition for the seed formation. B, in leaves, chloroplasts are free energy generators for the development of the whole plant. C, the chloroplasts in the bolls guarantee the complementary energy supply for seed development and seed ripening until the fi nal stage where the seeds are reliesd. Biochemical analysis will probably show in the future that the three different photosynthetic active organs leaf, bract and ball show very different constellations of enzymatic activities and metabolite productions.

Chlorophyll a fluorescence measurements and the JIP test

A plant efficiency analyzer (Handy PEA, Hansatech, UK)

A B C



(b) The specifi c energy fl uxes (per reaction centre, RC; in arbitrary units) for absorption (ABS/RC), trapping (TR0/RC=M0/VJ), dissipation (DI0/RC), electron transport QA

- to PQ (ET0/RC), and electron transport from Qa- to the PS I electron acceptors (RE0/RC). M0 is the slope at the origin to the relative variable fl uorescence Voj between Fo and FJ.

(c) The amount of active PS II reaction centres per ab-sorption (RC/ABS).

(d) The total electron carriers per RC of PS II or absorp-tion (EC/RC=Area/(FM-Fo) and EC/ABS=(EC/RC)(RC/ABS), respectively). The expression RC refers here always to the reaction center of PS II.

Chlorophyll fl uorescence measurement in the light acclimated state

Chlorophyll fluorescence was measured using a satura-tion-pulse Dual-PAM-100 fluorometer (Walz, Effeltrich, Germany). Prior to measurement, leaves, bracts, and cap-sule wall of bolls were dark-adapted sufficiently over 30 min). Fo (minimal fl uorescence) was obtained with a mea-suring light of about 0.5 mmol m-2 s-1. Fm (maximal fl uores-cence) was obtained with a saturating light pulse. The inten-sity and the width of saturating pulse were 10 000 mmol m-2 s-1 and 600 ms, respectively. After the sample was exposed to the intermediate PAR for about 4-5 min, the rap-id light curves were obtained with the Dual-PAM 100 using an internal program and PAR supplied by red light-emitting diodes. Ten discrete PAR steps were used (20 s each): 27, 58, 100, 171, 278, 435, 665, 1 033, 1 599, and 1 957 μmol m-2 s-1. Each light increment was followed by the measure-ment of Fs´ and by a saturating pulse for the measurement of Fm´. The fraction of absorbed irradiance consumed via steady state photochemistry ( PS II) was calculated according to the general equation of Paillotin (1976) where PS II (t)=1-Ft/Fm and measured in the light adapted state as (1-Fs´/Fm´) as done by Genty et al. (1989). The fractions of light, absorbed by the PS II antennae, that is lost by constitutive thermal dissipation and via the fl uorescence ratio Fs´/Fm called f, D, and the light absorbed by the PS II antennae that is dissipat-ed thermally via pH- and xanthophylls-regulated processes called NPQ, were calculated as Fs´/Fm and (Fs´/Fm´)-(Fs´/Fm), respectively (Hendrickson et al. 2004). The three yield terms PS II, f, D and NPQ are summing up to unity.

Data analyses

The statistical analysis of the data was performed by one-way ANOVA and least signifi cant differences (LSD) test at the 5% level of signifi cance.

AcknowledgementsThis study was fi nancially supported by the National Nat-

ural Science Foundation of China (U1203283, 31260295), the National Key Technologies R&D Program of Chi-na (2007BAD44B07) and the Special Launching Funds for High-Level Talents of Shihezi University, China (RCZX201005).

ReferencesAschan G, Pfanz H, Vodnik D, Batiè F. 2005. Photosynthetic

performance of vegetative and reproductive structures of green hellebore (Helleborus viridis L. agg.). Photosynthetica, 43, 55-64.

Bondada B R, Oosterhuis D M. 2000. Comparative epidermal ultrastructure of cotton (Gossypium hirsutum L.) leaf, bract and capsule wall. Annals of Botany, 86, 1143-1152.

Bondada B R, Oosterhuis D M, Wullschleger S D, Kim K S, Harris W. 1994. Anatomical considerations related to photosynthesis in cotton (Cossypium hirsutum L.) leaves, bracts, and the capsule wall. Journal of Experimental Botany, 45, 111-118.

Bondada B R, Oosterhuis D M. 2003. Morphometric analysis of chloroplasts of cotton and fruiting organs. Biologia Plantarum, 47, 281-284.

Constable G A, Rawson H M. 1980. Carbon production and utilization in cotton: Inferences from a carbon budget. Functional Plant Biology, 7, 539-553.

Elmore C D. 1973. Contributions of the capsule wall and bracts to the developing cotton fruit. Crop Science, 13, 751-752.

Genty B, Briantais J M, Baker N R. 1989. The relationship between the quantum yield of photosynthetic electron transport and quenching of chlorophyll fluorescence. Biochimica et Biophysica Acta, 990, 87-92.

Hendrickson L, Furbank R T, Chow W S. 2004. A simple alternative approach to assessing the fate of absorbed light energy using chlorophyll fluorescence. Photosynthesis Research, 82, 73-81.

Hether ington S , Smi l l ie R M, Davies W J . 1998. Photosynthetic activities of vegetative and fruiting tissues of tomato. Journal of Experimental Botany, 49, 1173-1181.

Hu YY, Zhang Y L, Luo H H, Li W, Oguchi R, Fan D Y, Chow W S, Zhang W F. 2012. Important photosynthetic contribution from the non-foliar green organs in cotton at the late growth stage. Planta, 235, 325-336.

Kalachanis D, Manetas Y. 2010. Analysis of fast chlorophyll fluorescence rise (O-K-J-I-P) curves in green fruits indicates electron flow limitations at the donor side of PS II and the acceptor sides of both photosystems. Physiologia Plantarum, 139, 313-323.

Kim E H, Li X P, Razeghifard R, Anderson J M, Niyogi K K, Pogson B J, Chow W S. 2009. The multiple roles of light-harvesting chlorophyll a/b protein complexes define structure and optimize function of Arabidopsis chloroplasts: a study using two chlorophyll b-less



mutants. Biochimica et Biophysica Acta, 1787, 973-984.Krause G H, Weis E. 1991. Chlorophyll fluorescence and

photosynthesis - the basics. Annual Review of Plant Biology, 42, 313-349.

Pail lot in G. 1976. Movement of excitat ions in the photosynthetic domains of photosystem II. Journal of Theoretical Biology, 58, 237-252.

Schansker G, Tóth S Z, Strasser R J. 2005. Methylviologen and dibromothymoquinone treatments of pea leaves reveal the role of photosystem I in the chl a fl uorescence rise OJIP. Biochimica et Biophysica Acta, 1706, 250-261.

Strasser B J, Strasser R J. 1995. Measuring fast fl uorescence transients to address environmental questions: the JIP test. In: Mathis P, ed., Photosynthesis: From Light to Biosphere. Kluwer Academic, The Netherlands. pp. 977-980.

Strasser R J, Srivastava A, Govindjee. 1995. Polyphasic chlorophyll a fluorescence transient in plants and cyanobacteria. Photochemistry and Photobiology, 61, 32-42.

Strasser R J, Srivastava A, Tsimilli-Michael M. 2004. Analysis of the chlorophyll a fluorescence transient. In: Papageorgiou G, Govindjee, eds. , Advances in Photosynthesis and Respiration: Chlorophyll Fluorescence, A Signature of Photosynthesis. Kluwer Academic Publishers, Dordrecht, The Netherlands. pp. 321-362.

S t rasser R J . 1978 . The grouping model o f p lan t photosynthesis. In: Akoyunoglou G, Argyroudi-Akoyunoglou J H, eds., Chloroplast Development. Elsevier/North-Holland Biomedical Press, Amsterdam, The Netherlands. pp. 513-542.

S t rasser R J . 1981 . The grouping model o f p lan t photosynthesis: heterogeneity of photosynthetic units in thylakoids. In: Akoyunoglou G, ed., Photosynthesis II. Structure and Molecular Organization of the Photosynthetic Apparatus . International Science Services, Philadelphia, PA, USA-Balaban. pp. 727-737.

Strasser R J, Sironval C. 1972. Induction of photosystem II activity in fl ashed leaves. Febs Letters, 28, 56-60.

Strasser R J, Sironval C. 1973. Induction of PSII activity and

induction of a variable part of the fl uorescence emission by weak green light in fl ashed bean leaves. Febs Letters, 29, 286-288.

Strasser R J, Srivastava A, Tsimilli-Michael M. 2000. The fluorescence transient as a tool to characterize and screen photosynthetic samples. In: Yunus M, Pathre U, Mohanty P, eds., Probing Photosynthesis: Mechanism, Regulation and Adaptation. Taylor and Francis, London. pp. 445-483.

Strasser R J, Tsimilli-Michael M, Dangre D, Rai M. 2007. Biophysical phenomics reveals functional building blocks of plants systems biology: a case study for the evaluation of the impact of mycorrhization with piriformospora indica. In: Varma A, Oelmüler R, eds., Advanced Techniques in Soil Microbiology, Soil Biology. Springer-Verlag, Berlin Heidelberg. pp. 319-341.

Tsimilli-Michael M, Strasser R J. 2008. In vivo assessment of plants’ vitality: applications in detecting and evaluating the impact of mycorrhization on host plants. In: Varma A, ed, Mycorrhiza: State of the Art, Genetics and Molecular Biology, Eco-Function, Biotechnology, Eco-Physiology, Structure and Systematics. Springer, Berlin. pp. 679-703.

Wullschleger S D, Oosterhuis D M. 1990a. Photosynthetic and respiratory activity of fruiting forms within the cotton canopy. Plant Physiology, 94, 463-469.

Wullschleger S D, Oosterhuis D M. 1990b. Photosynthetic carbon production and use by developing cotton leaves and bolls. Crop Science, 30, 1259-1264.

Wullschleger S D, Oosterhuis D M. 1991. Photosynthesis, transpiration and water-use efficiency of cotton leaves and fruit. Photosynthetica, 25, 505-515.

Wullschleger S D, Oosterhuis D M, Hurren R G, Hanson P J. 1991. Evidence for light-dependent recycling of respired carbon dioxide by the cotton fruit. Plant Physiology, 97, 574-579.

Zeliou K, Manetas Y, Petropoulou Y. 2009. Transient winter leaf reddding in Cistus creticus characterizes weak (stress-sensitive) individuals, yet anthocyanins cannot alleviate the adverse effects on photosynthesis. Journal of Experimental Botany, 11, 3031-3042.

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Characteristics of Photosystem II Behavior in Cotton (Gossypium hirsutum L.) Bract and Capsule Wall

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