Loveless 1964a

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Tram.lJ,it. 1/1)",,1. SOr..o{7 (2), '20j- '.!l3 (1964)'

Printed in Great 8rilaill

USE OF THE HONEYDEW STATE IN THE

IDENTIFICATION OF ERGOT SPECIES

By A. R. LOVELESSDepartment of lloiany, Universio' College of Rfwtlesia alld J{)'flsaland, Salisbury

(Willl 31"'xl-('gurcs)

Ahllough the stromal;!, of a species of Clav;ccps must be oll'crvcd bd,'n: a finalidentification can be nl<'ldc, the size and shape of the conidia of the honey.kw

state, considrrnl in conjunction with the h o . ~ t range, aT'- here u ~ , : d a . ~ . ' \ n>. ansof c h a r a c l , · r i ~ ; l l i , , , , . ' I 'h i f l<" " l gn,ups of conidia have b''''ll rc'-ogn;7.(,([ :l""I1'g

c o l l c c t i ( J n ~ "I' l111,,,;ydn,· Ii-"", i1,irty-four S. Rho.Jcsiall gras"·'. Six of d'esc

conidial gn,ops 'urn"sllOlId to till; six species of Chwiu/'.1 known to OCl"lIr in

S. Rhodl",;a.tl,c rnll"ininl!:seven groups would seem to I<-present undescrihedClaoiups spp. If conidial charae('·rs arc used (0 presume ~ p c c i e s dilT"erentiation,iris p o s ~ i h l c (0 S l 1 g ~ o ; : s t all t ; x ( e l l ~ i o n of (he recorded host ranges of alreadyd e s c r i b ~ - d crgOIS and also \ l ) predict hosts of und<:scribcrl oncs.

There afC thirty dcscribed species of Claviceps (Lwgdon, '954; Biblio·_ ~ r a p h y of Systematic 1 1 I ] c o l o ~ r , '953 onwards) which are distinguished from

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206 Trarzsactions British Mycological Society Identification of ergot. A. R. Loveless 207

the bboratory, whereas sclerotia or olher s p c c i c ~ cnmislclllly fail 10

germ inat e under t he same conditions. For an unkllown species therequisite germination conditions can be determined only by lrying anumber of different experimental treatments, and this may rCfj l l in' manysclerotia. Thirdly, even when stromata have been produced, wnical

sections through the capitulum must be prepared to determine the shapeand size of the pcrithccia.

In view of the above diO"iculties the possibility or using the honeydewor SpfJacelia s ta te as an easy means of identiftcation has been explored.Conidial mounts were prepared from ergotized innorcsCCIlCcs of as manyS. Rhodesian grasses as it has been possible to collect. S. Rhodesi<l is

particularly sui tabl e for such a s tudy becJ.llse, be ing predominantly aSaV;lIllla region, it is an area in wh ich an in tensive sea rch for crgols is

l ikely to reve;l l new host rccords and the presence or tlndescribed species,S ince Ig61, wben this inves tigation bcgan, conidia have been collected(I ll th irty-four spo;ies ofgrassl's of seventecII geller;l. '1'llI're ;\rc 1111( 1\ 11Ibtedlyrurtlll'r hoslS of C!m'icr{!J to be l'ITorded rrom S. 1{l!o\ksia, b e c : l . U ~ ehOIll')'dew has nol yet beell \ 'ol lct; \cd [i'olll ~ n ' n a l gl :ISSCS Oi l whichCtr,'brlla andro{!ogollis Cesali (or f,jJ;co({//TI/ fllldm{!o.!:'I/I;,\ (Cl's.) Schol

Schwa1"7:) has been recorded in this eOLlntry. From the \lork of LlIlgdon(Ig.pb) there is littlc doubt that this fungus is a lloncydl'w s:lprophyte,:lnd that the finding of it on a grass is a safc indic:ltion or [1n::vioLls infection11 ilh a species of ClllviC1'l's. I t is worth mentioning tlwrd'lre th:lt the

conspicuous, black, convoluted mY\'clium of Cachet/a (/Ilrlmj;ov()IIis 011 gr:1SS

infloresccnees Ins proved:l most USdll1 fidd indic:ltlll" III l'l1.('ltiz('(1 plants..\!though the growth of C. (/Iu/mjlOgol/;s all an illfi.:ul'd ~ I , i k e l c t suppressesIbc den:lupmell t of ClariujJs in Iha t spi kclet, a Cl ]'I·fu I se;\ rd l Ileal' Cacbella-inli.:etet! plants often revcals all uncontaminated llollcydel\' state thal

l\lighl othcr\\'ise ba\"C c ~ c : l J l e d nOlice.

:\IETHOO OF RECORD1"G TilE SIZE A",D SIlAI't:: OF HONEYDEW CONIDIA

The conidi;\ of C{oi"iccjJs ~ p e c i e s arc known In sIll IW eonsider:lbll' \'a rbl ion

in size and sklJw bOlh bel\\"cCll :md within SIW( ies. Tl) record lhc degreeof v:lri:ltion wilhin anyone conidial mounl. lhe outliucs of t\\'enty-liverandom spores,' x 300) were traced on 'Ethuloll' 1'..\[, Tr:lcing Filmalt:lchcd 10 the screen of a Rcidlcr t L: lnametn. Thl ' dimension" of eachSp'IlT \ITrC measlIl'I'd and the r;lllge in sll;IJ)(' of tIll' s;llIll'k W;I.S illdicateubv placing: thc OUlliues side hy side ill on!t;r or i l l c r C ; I ~ \ l ' o . : sp"re length.'For each species of ergolized grass lelllr sep;\I';\le conidial mounts were

examined. Th e [our mounls were invar iably laken frOl\\ Jillcrellt plantsand where possible tbey WCl'e selected so as to represel1l widely sep:lratrd

localities in S. Rhodesia and different seasons of collection.

RESULTS

The conidial mounts, as a. whole, differed very noticeabl\ ' in appearance,

in deciding how to classify the conidial mounts, it was considered necessary10 take host range into account as well as spo re morphology. Excep t for( ~ purjJurc{/ (Fr.) Tu!., all other known species of Clav;ceps are recorded ashaving a rela tively narrow host range res tr ic ted to grasses belonging to..ne panicular tribe. ~ ' [ o s t species have a monogenerie host range, whilstothers are found on scveral genera restricted to a single tribe. C. purpureais unique in that it is r ecorded as having a very wide host r ange , spread

over members of several tribes, bu t even so it is apparently restricted(Langdon, 1 9 5 ' ~ ) to grasses of the subfamily Pooide;'e (sensu Stapf, 1'.)19).Wben the host relat ions of the twelve morphological groups of conidia

were considned, one group did not conlorm to the general restriction of

elavice/is species to particular host t:n::a. This morphological group wasrecorded fl'om both Sorghum caiJrorulIl and Loudet;a simplex, two grasseswhich arc Ilut only of different tribes bu t also of different subfamilies of

the Gratllill(';\C. It is extremely unlikely that the same species of Ciavicepscould infq:1 ~ u c l i wid,-Iy different grasses. This morphological group is

therdore I'q llTsell ted t\\ ice ill the ebssi[ication or conidial IIlOllll ts, oncein tile l'o..it!l-ae :ll\llllllcC in the l'anicoidc<le, lhereby incre:lsing the totalnumber of groups rccognizcd !i'om twelve to thirtl"\.'n (Table I) .

III aClIJrdanee with expectation, the four conidial mounts from anyonehost species all fit ted with the same group. TIlc conidia of certain groups

are so distinctive that they can be e:\sily recognized at a glance. Th e smallreniform conidia of group tOll R/!1'IIchl'/)'II"IIJII /"fjims and the large' fa\catcor fusiform conidia of .<..:H)IIP 7 Oll Cl'llc!lrus (if/(/ris and Penllisclum ~ r p h o i d e s:Ire examples of sllch di.stilll'ti\"{' cOllidia. ,\ dct:lilcd cxalllinatioll of thesize and sll:l]>e of the ~ p o r e s \I'ilhilllhc v a r i O I l ~ groups \ \ ' i l \ sllow, h'l\\'ever,that ca d I I dislinct from mher groups on the same . ~ r a s s lribe. In factIllOSt grOllp, can be srpar:l .\"d solely on the basis of mean spore length{Fig. 3;. \\'here the conidia nf t\\'o groups arc very similar in lenglh and

thus indislinguishable on this b:lsis, they call nevertheless be separ:\lcd by

their respn:tive shapes. Thus, whcreas the eOllidia of C. digitariae (group 5)"nd C. S1/{Olta (group G) cannot be distinguished by spore measurementsalone, the [;ll'lller h:ls pred\lIllinamly ellipsoid and the latter predominantly

:lllalltoid spores. In view of the inevitable variation in me;lll t e I l ' ~ t h s of

diO'crent s;lI11plcs of the same species, the author has !ound the l e l t ~ t h tobreadth r:1tio a most useful accessory character to spore length in cla: ;i!"yingconidial sallIples. This r;llio b:lS been lI"idely used lO gi"" an i l' dex ofshape :l11\1 in lhis \l"I\rk tl'IHkd 10 be nmsl;\l\t 101' a gi\ 'cll species, evcllthough the IIIC:llI dimcllsiollS of different samples v;\ried sOlllewh:n,

CONCLUSIONS

On the assulllption that e3ch group of conidia represents a. distincttaxon, the honeydew stales fWIll the lhirty-four grass species can beassigned to Ihirtecn species of Claviceps. Before Ig61 on ly four namedspecies of C!rw;cejJs (c. C)'lIodont;J. C. digiltlliae, C. paspali and C. sulca/a)and two undetermined species (onc on Pal/hum maximum and another 011

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TramQctions British Myc%gical Society

200

H Tribe: PanleueI .- • ----I

...--- • -- ;10·8

I .. ---- --;

11-8I .- • ----oj

U8, .. --- • ------1

13'8; 1------------ , --------1

1S·8l - - - - - - - • -------oj

16,0l

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10·11Tribe: Andropogonue-

.--• ----- . ;

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13-S Tribe: ChlorideaeI ~ - - - - - - -- ,

13-8 Tribe: Arundinelleacl 1---------- • -- - - . ;

,.-15

Spore length (#)

Fig. 3· The ranges and means of 'pore l ength for the thi rt een group5 of honeyd,'"conidia. The dotted portion, of the range lines indicate the tail 5-10%of the frequcnC)"distribution at each end of the range.

Ide1llification of ergot. A. R. Loveless 21 I

C. pusilla. Both are believed Lo be new r{;cords for southern Africa, thoughthe former merely represents the identification of the ergot on Panicumonaximum that was known but had not been identified.

The conidia of the six named species of Claviceps correspond to six ofthe thirteen conidial groups recognized above. There is no availabled,·scription of the conidia of C. digitariae, but the ergot associated in S.Rhodesia with Digitaria diagonfllis and D. ga<.tnsis has been confirmed as( digitariae by successful germination of the sclerotia. For the other fivea;nhenticated species, the conidial characters (Table I) agree reasonably

well with those given eidler in the type or in subsequent descriptions.It has not been possible to equ<lte the remaining seven groups ofconidiawith any known species (of (lavio!ps. From considerations of host rangeil would seem that most, i f n, ,t all, of them belong to undescribed species,but this can be established only by observing the stromata produced bygermination of the sclerotia. Attempts are being made to germinate

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20ts "J'ransactions Brit ish Myc%gical SopelY

SOa-FAMILY; PAN1COlOEAfTribe; P ,nicue

Group 1 C, rhynchelytri

aOOaOOOOOGOOaOaOOGGOOOaGG

Group 2 (C. P I ~ P I I I )

UOOOODOOOOOOOOOOOOOOOOOOOGroup J

0000000000000000000000000\

Group 4 f

o o o a O O O O O O O O O O O O O O O O O O O O ~Group 5 (c. ditiurlu)

O O O O O O O O O O O O O O O O O O ~ O D O O O ~Group 6 (C. JUkIU)

o o G Q Q G ~ G G ~ G G G O O ~ O G G G G O d ~ GGroup 7 C, fusiformis

o o o o o o ~ ~ o ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ d ~ ~O O O O O O O O O O O O O O O O G G O O O O ~ O O

Fig_ I. Spore umples or the e ighl conidia l groups d i ~ t i " . ! : \ l i $ h ~ ' { 1 011 S. Rhodesian .grasses belonging to the t ribe P:r.niecae, E."lch sample CQllsisll or ~ ralldolll spores()C ¥'Cl),

Idemifi<;alion of ergot. A. R. £Qveless 209

SU8-FAHILy : PANICOlDEAE (eone/nlltd)Tribe: Andropocone1e

Group 9 (C, puSWI)

O()()()() OOO()()0l]O()()OO O(]OOO OOGG I .

C. africana

0000000000000000000000000G 11

Claviceps Sp. HYP

oooooooOOOOOOOOODOOO

00000

SUB-r \HILY: POOIOEAl:

TrIbe: Chloridele

Group 12 (C. cynooOl'ltls)

ooOGOGGGGeuOGOGOGddOGGddG

Tribe: Arundlnellue

Group 13 Claviceps Sp. LOU

0000000000000000000000000Fig" , Spore samples of the five conidial groups d ~ l i n g u i s h e d on ~ RhodesianITauet belonging to the tribes ,\ndropl!gonc:ac. ChlQrlde:l.e and ,\rundmelloe. Th esamples are drawn at Ihe same magnifies-don (le ¥JO) :i s those in Fig. I.

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(AtUpltdfOT p1/blicaJion 8 August (963)

REFERENCES

LA/'tGDO/'t, R. F. (1942a) . Ergot ornativr grasses in Quunsland. PTtX. ro:!. Soc. Qd 54.23-32. '

WGDO/'t, R. F. (19420). The genus CTrbtlla Cesati-its biologic status and we. Phylo/NJI!toloD, 32, 613-017.

I..vtODO/'t, R. F. (195i ). The origin and differentiation of Clauiups species. VI/iD. QdPap. (1101.),3, fil-68.

Lonuss.. A. R .. (19"4). Studies of Rhodesian ergots. I. Cltwitrps ma.nmrlUU Theis andClaDIUPS

",mUD <eati. KiTkia, 4, 35-40.Sn.p" O. (19 '9 )· ( ;r amineae (incomplete). In Flora of Tropuaf "friea g. AshrordKent: L. Reevc and Co. ' ,

2 I2 Transactions British Myc%gical Sodety

indicated above, this is likely to prove a lengthy process " C C a l l . ~ C theappropriate germination conditions are unknown.Besides the general conclusion that there are probably several un

described species of Clauiups in S. Rhodesia, the following addit ionalpoints arising out of this investigation deserve mention:

(I ) On the basis of the occurrence of the very characteristic triangularconidia of C. pUJilla, it is safe to extend the recorded host range of thisspecies to include the genus HyporThLnia. A similar conclusion may also

be tentatively drawn for C. sultata. This ergot has hitherto been recordedonly on BrlUhiaria spp. but allantoid conidia similar to those of C. sulcala

occur also on Urodtloa, closely related to BraclliaTia. It seems likely therefore that Uroddoa is also a host genus of C. micala, though this can be confirmed only when sclcrotia from Ur()thioa have been germinated.

(2) The occurrence of conidia of the same rather unusual f,,\catf' Jlhapeon both Ctnc!lrus ciii"Tis and P t ' l R i S i ~ l u m tJ/1!loitlrs would indie.lle tllOll theseare both hosts of the same Ciauiceps, which is almost certainly ;111 un-described species. It may be possible, therefore, to predict the host range ofan ergot species not yet dc...'scribed.(3) Although most CinvicejJs Jlpp. have a r c l n l i ~ y narrow host r.mge,

it cannot be nssumed that the dilferent species of onc host genus will

a lways be attacked by the same ergot. From the present study it seemsa Imost certain that the ergot of PnlliCll1ll roloTalul/I is not, as mi)..:"ht be expectedun a Iiost basis, the same as tha t on P. maximum. Simil:uly, J-(I'flarrlltl/iaappears to be parasitized by two species, C. pusilla alld another (withconidia in Group 11 ) that is probably undescribed.(4) Judging from the host records it would seem that Ciauiup.r has

cvolved along ...ery different lines in the two subfamilies of thc Gramine;1e.In thc Panicoideae it has apparently evolved into a number of distinctspecies, each with a restricted host range. Th e results of the prCJlcnt in-vestigation endorse this view. In the Pooidcac, by contrast, physiologicall:volution does not seem to have been accompani ed by a concurrentmorphological evolution. Only six Ciaviups species are known on grasses

of the Pooidene, and four of these arc reported to have a monogenerichost r ange: n fiflh, C. iiforalis Kawatani, is recorded 011 El.pm'.f andIf/m/mm in .Jnpan. ,.\[1 othcr crgots rccorded li·om the Pooid,·ae, covcringnearly 200 host spccies of li tribes and 50 gCllera (Langdol1, 1 9 5 ' ~ ) , arcascribed to Clavictps pflTpuTta. The author wonders to what extent the

tremendous width of this reputed host range is the resul t of arbitraryidentifications rather than genuine physiologic specialization. I t is

suggested that a critical examination of honeydew conidia from recordedhosts of C. pflTpflTea, of widely differing taxonomic status, would be well

worthwhile.

I am grateful to t\[rJ. B. Phipps and 1,,[rs Luey Crook (nee Chippindall

of the Federal Herbarium, Salisbury, for invaluable help in identifyin:: ,ergotized grasses, to Mr A. R. A. Nod lill· reading the manuscript, andto my wife for continual assistance throughollt the work.

Identificatiqn of ergot. A. R. Loveless 213

Loveless 1964a

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