Inouye, T.

Nisikado, Y.

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ON THE SEXUALITY OF THE WHEAT SCAB FUNGUS, GIBBERELLA ZEAE (SCH.) PETCH*

Okayama University Scientific Achievement Repository

ON THE SEXUALITY OF THE WHEAT SCAB FUNGUS， GIBBERELLA ZEAE (SCH.) PETCH* By Y. NISIKADO and T. INOUYE 1. Introduction 民 dge(1) demonstrated that N eurosporαtetrasperrrω， which develo戸dasci with four bise玄ualspores， was normally homothalli巴;while N eurospora sitophila and N. C1assα， in which the asci were eight spored， was hetero-thallic. The heterothallism of some species of CeratostomeUαand GlomereUα has been shown by Buisman and others. The se:x.uality of GibbereUa Zae (Sch.) Petch=G. Sαubinetii was studied by Eide， who secured 72 isolates from the hyphal tips cut of the germ tubes of germinating conidia and • ascospores. As the isolates produced perithecia， with 2 e:x.ceptions， he con-cluded Gibberella Sαubinetii to be homothallic. The present writers (6) have also studied on the sexuality of the wheat s巴abfungus， GibbereUa Zeae. 1. Materials and Methods In the present e:x.periments， single a配osporeisolations were made from the perithecia secured from the following four sources: A) Perithe巴iaformed on steamed rice straw cultured in a r伺 gentglass bottle by the fungus No. 2352 of the Ohara Institute. This line was originally isolated from a scabbed wheat ear coUected in the prefecture of Toku日hima，July 1951. B) Perithecia produced on a diseased ear of Huron Ottawa wheat grown in the e玄perimentalfield of the Institute. C) Perithe巴iafound on a rice straw pile of a field near the Institute. D) Perithecia formed on an ear of an unknown ，'ariety of wheat grown in a greenhouse of the Institute. F'rom the sources A， B， 0 aud D， the writers isolated 24， 12， 30 and 58日inglespores respectively. For isolating the spores， the method devised by the senior writer (3) was used， in which the perithecia， first washed carefully with repeated 巴hangesof sterile water， were crushed with a sterilized needle on a sterilized slide to release the ascospores. These asco. spores were diluted and smeared over the surface of agar plates in petri dishes. ‘Investig8tion aided by the Research Fund for the Plant Protection iro皿 theMiniotry of Agricul tu開8nd Foreotry. The experi皿el¥tw制。hieflycarried out the by the jUl¥Ior 8uthor 8nd the preparation of the ra・nu舵 priもW師同lIiltedby Mr. T. N・kayama(Bd. 10， Ht. 2 By p1a巴ingthe petri dishes in an inverted position on the stage of the micro-scope， each ascospore that has shown germination was marked at the bottom of the dish with ink. The portions of the agar thus se1ected with sing1e spores were cut with a p1atinum micro-ring 2mm in diameter and finally fished out with a micro-spatu1a in句 po也to・de玄tro間 agarslants. To test the formation of perithecia， the method a1旬 reportedby the senior author (4) was used. Each sing1e ascospore cu1ture or mixed巴ultureof two iso1ates was inoculated to the steamed rice straw sta1ks p1a巴edin reagent glass bottles and allowed to grow for about two weeks at 30~C. When the stalks were fully covered with the mycelium of the fungus， they were transferred to a beaker 18cro in height and 5.5cm in diameter for the formation of perithecia. These beakers， after adding a small amount of water and covering with a thin Japanese rice paper， were p1aced near a window partially exposed to the sunshine. Berichte d. Ohara Il.8titu旬.54 Experimental Results The perithecium formation in the roixed cultures of two single ascospore isolates was studied by the roethod described above. The resu1ts ar巴 givenin table 1. In this table the perithe巴iuroforrnation is e玄pressedby the nurober of plus signs for density and p1us minus自ignfor a very poor formation. 11 ???• ???????????????? ? ???????????? ? ? ?Table 1. TM peril1uciu鴨 lor構alionω 1M"，iud cullures 01師cht削。1lhe sIlfgle a脚明開閉lal館。'1G仰向laZeae Peteh. 19 20 21 +・+・+・18 + 15 16 11 主・+・*14 + ??12 * 10 11 *・*??? ??8 * 7 # 6 iI十28 29 30 主+:::t:・24 25 26 27 士+土・土21 22 23 土*+'事土??•• ??12 + ? ?????6 + ??37 38 39 士事土・士36 * ???? ? ? ??????????????31 * 29 30 *・士? ?27 * 26 * 25 * ? ?22 23 +・+10 12 士**? ?????10 11 主'*+ 9 + ??+ 6 + 5 * ? ??16 17 18 19 .20 21 土*土*土*土*士*土15 + 14 + ? ?12 + 9 10 11 士*土'**??????• ??Al X BI X ?????????????34 35 36 37 * +骨十33 * B 12 5 +'* + 31 32 士‘+28 29 30 士事士事十27 *. ????24 廿23 t十n + 19 20 22 骨骨土789 +*+ 5 6 *‘土Remarks: A¥ X B5-1宮， Bl X BI-1t are the resulta observed after 2 days' incubation in the tall bellkers j A¥ X CI~_凹， BI X Al-1f， Bl X 0!-15， Cl x AI_II， Cl X B5-1!， Cl X C，ー畑 arethe resul ts after 3 days' incubation; and AI x A!-zt， Al X D副ー剖， Bl X D~I-4o a四 theresul ta after 4 dayo' incubation. * An asterisk shows the cul ture， in which p時 ttyg剖泌 peritheciu血 formationwas observed in a week's incubation in the regent gl胡 s，after the皿ediumw拙 transferr吋 f四時 thetall beaker. 18 骨? ?15 16 17 士*主*+14 + 13 + ? ?12 *10 + 11 + ????? ? ???8 + 5 6 土'** 7 + 4 * ????C1 X 1954) Nisikado & l!Iouye: Sexuality of Gibbe問1ZaZell6. 55 Resuts on similar experiments for the individual ascospore isolates are shown in table 2. As in the曲目eof the mixed cultures， the single spore isolates also produced perithecia， but their density varied with the isolate. Mature凶巴倒poreswere observed in all the perithecia formed. A Table I. The peri''ue似蝿伊川仰向山仰向 culture8of each of the aiflgle a脚 S仰向 isolat68of Gib加 elaZ剖 ePeteh. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 ** + *ホ土**** + t十主+*'" t十'"+ + +傘 C+*+4++++*+ .A B 22 23 24 1 2 3 4 5 6 7 8 9 10 11 12 1 ー2 3 4 5 6 t主骨骨*'"**骨骨骨本朴+**'" ** *'" * +* +土土+土*7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 +C $+十*土*+D+f + 土'"+ ** +'" +* + +'"士市+*+* + +'" + +ホ+*28 29 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 ま*土"'+* *"'* *"'* it十*+**********+D 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 +D +*++*++*++*+感*+ * *土土*ホ+*+*士事*取*‘**~ u a ~ < ~ ~ U s U W ~ ~ ~ .54 ~ ~ M ~ 全..t+ +・+士ホ士・+士 + :% ::V~ * +ホ*+'"士.*'" +* Remarko: .Al-.A!4， BJ-BI!， DJ-D相 8howthe results observed after 4 days' incubation in the tall beakers and Cl-C拘 thoseafter 3 days' incubation. . .An asterisk ShOW8 that the culture produced the peritheeia pretty well after a week's incubation in the reagent glass U8ed. The results of the e玄perimentsgiven above show that al of the 124 single ascospore isolates without e玄巴eptionproduced perithecia and mature ascospores. They lead to the conclusion that Gibberella Zeae Petch is homo-thallic， as shown by Eide (2). IV. Summary. 1. The pre田ntpaper deals with the sexuality of the wheat.scab fungus， Gibberella Zeae (Sch.) Petch=Gibberella Sαubinetii (Mont.) Sac. 2. 124 single ascospore isolations were made from four different回目伺Sof perithecia. 3. The perithecium formation was te目tedon the isolates or mixed cultures of two of them by first growing them on steamed rice straw stalks in reagent glass bottles， and then transferring the stalks to a tall beaker when they have shown a growth巴overingthe entire surface of the stalk with the fungus mycelium after filling with a small amount of water and covered with a 池田tof thin Japanese rice paper.， The beakers were set n伺 ra window partially e玄posedto sunshine. 4. By this method， mi玄edcultures as well as individual ascopsore isolates produced perithecia and matured ascospores. This demonstrated that the isolates of Gibberella Zeae (Sch.) Petch is homothallic， as shown by Eide. 56 Berichte d. Ohara laotituts. (Bd. 10， Ht. 2 Literature Cited ( 1) Dodge， B. O. (1927) Nuclear phenomcna a88∞iated with heterothallislft and homothallism in the Ascomycete N，郎 ro&pora. Jour. Agr. Res. 35 (4) : 289・305.(2) Eide， C.G. (1935) Pathogenicity and genetico of Gibberella岨ubinetii(Moat.) Sacc. Univ. Minn.， Agr. Exp. 8ta.， Tech. Bull. 106， 67pp. (3) Nisikado， Y. (1938) on a simple method for iaolating siDgle spore culture of fungi. Agriculture and Horticulture 13 (1): 96・102.(In Japane回〉( 4) Nisikado， Y.， K. Hirata & K. Kimura (1938) On the peritbecium form.atioD of the wheat S叫 bfungus， Gibbe開1saubi・制li(Moat.) 8ac. Nogaku Kenkyu (Japanese Edition of the Report of Ohara 1nstit. for-Agr. ReB.) 30 : 415-443. ( 5 ) Nisikado， Y. (1940) Reviews on the kn.何 ledgeof the sexuality of plant pathogeDic fungi. Plants and A'包imals8: 167・172.(In Japanese) ( 6) Nisikado， Y. & T. 1nouye (1953) on the嗣 xualityof the wheat scab funguB， G品加ellaZ曲 6. Nogaku Kenkyu (Japane回 Editionof the Ohara 1nstitute for Agr. Reaeareh) 40 (4) : 191・194. (In Japane回)， 

ON THE SEXUALITY OF THE WHEAT SCAB FUNGUS, GIBBERELLA ZEAE (SCH.) PETCH*

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