チューリップの白色疫病に関する研究 I : 疾病とその病原菌について(農学部門)

1951年以来, 戦後初めてオランダから輸入されたチューリップの球根に, 貯蔵中の腐敗が目立って多くなり, 栽培者の間で問題になった。従来の研究者達はその原因を研究してFusarium菌によるとしたが, しかし筆者は種々の点で疑問を生じた。本病菌は, 球根ばかりでなく, 葉, 茎, 花, 根などチューリップの各部位を侵す1種のPhytophthora菌で, 水浸状暗色の病状を呈し, 葉では葉先あるいは葉縁に乾くと灰白色の病斑を生じ, ヨーロッパ北部のリーキに生ずるいわゆる"white tip"に類似している。貯蔵球根は, 夏の高温期には腐敗を生じないが, 秋の冷涼期に入ると腐敗がはじまる。圃場では定植の直後から4月ごろまでの低温期に発生する病害で, とくに3∿4月のころが最も甚だしい。その被害はまことに甚大で, 今後のチューリップ栽培上憂慮すべきものがある。本病菌は, 発育の温度範囲が0°付近から28℃より少し低い付近で, 発育適温は20℃ないし15℃付近であり, わが国ではまれな好近温性の病菌である。種々の培地上で卵胞子を豊富に形成するが, 遊走子嚢の形成は病患部と培地ともに良好でない。しかし液体培地中に発育せしめた菌糸を水中に浸漬すると, 遊走子嚢を形成する。本病菌は, 筆者がすでに報告したラッキョウ白色疫病を原因するPhytophthora porri Foisterとまったく同種であり, チューリップの新病害として, 病害の和名を白色疫病と命名したい。なお始めて本病菌の厚膜胞子を記載した。The bulb rot of tulip (Tulipa gesneriana L.) has been recognized conspicuously in progress of its storage since 1951,which is the opening year of import of the bulb of tulip from the Netherlands after the War. Some of the investigators in Japan reported in the past that a causal fungus of the bulb rot is the Fusarium. However, the present writer will not agree to this opinion. Not only on the bulb does a disease by the Phytophthora occur but also on all such parts as leaf, stem, flower, and root of tulip taking on water-soaked dull color. The lesions of the leaf blight become, however, gray-white under dry weather like the "white tip" of leek as seen in Europe. Pure isolation of the fungus, Phytophthora, causing blight and rot of tulip, must carried out under the temperature 20℃ or below, inasmuch as diseases of tulip take place during a period of low temperature in Japan. Rots of the bulb in storage are severely observed in a cool period of the autumn, but not in the summer. The tulip disease by the Phytophthora occurs during a period of low temperature from the autumn through the spring, being especially severe in open fields in March and April. Zoosporangia of the causal fungus is not usually observed on the lesions of tulip and the lesions will be covered soon with bacteria and then Fusarium. The fungus in the present observation grows between the temperatures of 0℃ and 28℃ with the optimum temperatures 15℃ and 20℃. Oospores are formed abundantly in the various media, but zoosporangia are done very few. When the mycelium of the fungus growing in any liquid media is transplanted to the cool water, many sporangia will be formed in two or three days. The forgoing experiments on the fungus, Phytophthora, of tulip lead to the conclusion that the disease should be a new kind to tulip in Japan and the organisms be identified as Phytophthora porri Foister which causes a blight and rot of scallion, of which the writer reported previously. And chlamydospores are founded in the experiments for the first time

On the Influence of Temperature to the Germination of Zoosporangia of Phytophthora capsici LEONIAN

1. This paper deals with the experimental results on the influence of temperature on the germination of zoosporangia, formed on the fruits of pumpkin artificially inoculated with the fungus Phytophthora capsici LEONIAN. 2. The experiments were carried out by using a hanging drop of zoosporangial suspension on a slide glass enclosed in Petri dishes respectively kept at room temperature (11°-12℃), 16°, 20°, 22°, 24°, 26°, 28°, 30°, 32°, 34°, 36°and 40℃. 3. From the experiments the zoosporangia germinated with either zoospores or germ-tubes. The germination with zoospores took place between 16°and 26℃, with an optimum of 22℃, and that of germ-tubes between 11°and 36℃, with an optimum of 26℃. 4. Maximum and minimum temperatures of the zoosporangial germination with germ-tubes were similar to that of the mycelium growing on agar media but those for the germination with zoospores were somewhat different. 5. In these experiments, the germination with the germ-tubes was found to be more vigorous than that with the zoospores

Phytophthora capsici LEON. の遊走子のう形成機構研究のための抗生物質の利用(農学部門)

菌類の器官形成についての研究は, そのほとんどが形態の観察ならびに代謝産物の増減に関するものであって, 形成機構を制御する見地からのものはまだ数少ない。筆者らはPhytophthora capsiciの無性あるいは有性生殖器官の形成について引き続いて研究を行なっているが, この制御機構の研究のために形成刺激が随時に与えられ, また除かれるような手段が必要になってきた。刺激方法はいろいろとあるが菌の方の反応の速やかさという点から細菌によるP. capsiciの遊走子のうの形成促進効果を指標とすることにした。この細菌による形成刺激を希望する時点でとり除くために抗生物質を用いることにしたが, この物質は1) P. capsiciの発育を阻害しない, 2) P. capsiciの遊走子のうの形成能力を低下させない, 3)遊走子のう形成刺激能力をもつ細菌を速かに殺すか, その刺激機能ををいちじるしく低下せしめる, などの3つの条件を満たさねばならない。Penicillin G Na-salt, Polymyxin B sulfate, Vancomycin HCl, Dihydrostreptomycin sulfate, Chloromycetin, Cycloserine, Spiramycin, Gentamicin, Kanamycin, Colistin及びPentrexについて濃度を変えて刺激除去剤としての効果を検討した結果Pentrexが比較的よく上記3条件を満し, 使用濃度も1250ppmでよいことが判った。Regulatory system on the sporulation of fungi was investigated in Phytophthora capsici LEON. with referrence to the application of antibiotics For the induction of sporulation it is necessary to utilize adequate stimulants and inhibitors. Light stimulation is not suitable for this study, because the morphological change in the fungus proceeds too slowly after irradiation. By the same reason, temperature regulation and the dilution of nutrition in culture media are not unfavorable. On the contrary bacteria, SPB-3,inoculated together stimulate sporulation of the fungus rapidly and zoosporangia are formed completely within 120-150 min after contact with the bacterium. For furthee study it is desirable to get the substances which stop the bacterial stimulation to the fungus whenever occasion arises. Therefore, effects of some antibiotics on the growth of P. capsici and SPB-3 were investigated in regards to following 3 conditious to be required : 1) hyphal growth of P. capsici is not inhibited by antibiotic substance and 3) stimulatory bacteria for sporulation are killed or the stimulatory function is destroyed by the substance immediately after the substance is added to the fungal colony. Penicillin G Na-salt Polymyxin B sulfate. Vancomycin HCl, Cycloserine, Colistin, Spiramycin, Dihydrostreptomycin sulfate, Kanamycin, Chloromycetin, Gentamicin, and Pentrex are tested in line with conditions described above. In Penicillin G Na-salt, P. capsici grow well at concentrations tested, but the sporulation ability is reduced with ncreasing concentration and SPB-3 is not killed even at high concentration. In Polymyxin B gulfate, the growth of P. capsici is not inhibited so markedly, but the sporulation ability of the fungus is reduced at high concentration. In Vancomycin HCl, Cycloserine, Colistin and Spiramycin, SPB-3 is not killed. In Dihydrostreptomycin sulfate, the growth of P. capsici is completely inhibited even at low concentration, but resistant mutants are grown frequently. In Kanamycin, P. capsici don\u27t grow. In Chloromycetin and Gentamicin, the fungus don\u27t grow well. In Pentrex, P. capsici grow well at high level and the sporulation ability of the fungus is not lost. In addition SPB-3 is killed at high concentration. From these result on 3 conditions mentioned above, Pentrex 1250 ppm is recommended for the study of the regulatory system of the sporulation of P. capsici

Pseudomonas sp. による Phytophthora capsici LEON. の遊走子のう形成刺戟(農学部門)

京都府立大学付属農場土壌中より分離した細菌によるP. capsici菌の遊走子のう形成に対する刺戟について検討を加えた。P. capsiciが細菌と接触してから遊走子のうの完成までの最短所要時間は4∿5時間であり可視的な変化は20∿30分で生じる。細菌はけん濁液としてP. capsiciの培養の上に滴下するのが効果的であり, 供養疫病菌の遊走子のう形成能力の程度によって反応の現われかたが異なる。また刺戟能力はすべての細菌に非特異的に保有されているものでなく, Pseudomonas spp.にその能力が平均して高いようであったが, 刺戟の本体はなお不明である。供試細菌の令は培養1週間程度ではその刺戟能に有意差がない。しかし培地pHが酸性側(pH 4.0)ではこの刺戟の発現がなく, 中性から弱アルカリ性に移行するにしたがって効果が増大する。これは細菌側の増殖に好適であることも考えに入れられるが, むしろP. capsiciの側に遊走子のう形成の準備が整ったと見るべきである。同様のことは温度についてもいえることであって, この刺戟適温は菌が細菌以外の遊走子のう形成の場合の適温と一致する。培地も本来疫病菌の遊走子のうが形成され易いものにのみ刺戟効果が現われやすい。以上のことから, この刺戟はあくまでも遊走子のう形成経路への引き金の役目をなすだけのものであって, その経路を進むための物質的な素材を与えるものではないと考える。本細菌は遊走子のうの形成を促進するとともにその形も僅かに大型にする。また遊走子のうから遊出した遊走子を溶解する。刺戟効果をいちじるしく示す故に諸実験に用いた細菌は, Pseudomonas riboflavinaにきわめて類似した性質をもっていた。The stimulative effect by soil bacteria on zoosporangium formation of Phytophthora capsici (stock No. 65 isolated originally from egg plant) was studied under various experimental coonditions. This stimulative effect appeared within 20-30min. after the bacteria were in contact with Phytophthora, and the zoosporangia were accomplished following 4-5 hrs. Such bacterial stimulation did not spread over the bacterial colony. The culture filtrate of the bacteria passed through millipore filter did not show the stimulative effect. These results indicate that the stimulatiive substance might be short life metabolic product or products, so contact with living bacteria is necessary for zoosporangium production of Phytophthora. Bacteria transferred from broth cultures show larger stimulative effect than transfered from agar slant media made from the same nutrients. Among 15 Phytophthora cultures over 8 species, 3 species were stimulated by the bacteria but other did not show such a striking responce. These unsusceptible Phytophthora produced no or few zoosporangia even under natural condition, originally. Among 12 species of bacteria tesed, Pseudomonas revealed the most active stimulation. There was no appreciable difference in stimulative activity through growth stage or age of the bacteria in broth culture until 7 days. At weak alkali pH range of culture media both the bacterial growth and the stimulatory effect were increased, more than acidic condition. Phytophthora mycelium grown on oatmeal agar media was more rapidly react with the bacteria than PDA, and the mycelium grown on broth agar media could not produce zoosporangia in spite of the presence of the bacteria. The bacteria destroyed the zoospore of Phytophthora but not zoosporangial membrane. From the results of the test on the physiological characteristics of the bacteria, it is considered that the bacteria is Pseudomonas riboflavina regardless of the fact that the result did not show quite agreement with Bergey\u27s description

アラカシ Quercus glauca THUNB. 葉の新病害「輪紋葉枯病」とその病原菌について

1. 1956年11月初旬京都府相楽郡笠置町, 同12月中旬京都市左京区徳善谷, 1957年5月初旬神戸市諏訪山の谷, 1958年11月中旬京都市北区鷹ケ峰において, Quercus glauca THUNB.の葉をひどく枯らす病葉を発見し, 更にその病原菌の純粋分離培養に成功した。2.本病菌の侵害を受けたアラカシ葉は同心輪紋状褐色, 又は灰褐色の病斑を形成し, その上に光沢ある黒褐色の小隆起(分生胞子堆)を散生する。分生胞子は通常有色細胞2つ, 稀に3つを有する。頭部に鞭毛2∿4本を有する。分生胞子の大さは12.4-15.5×5.3-6.2μである。3.本病原菌の菌糸発育最適温度は24℃附近, 最高発育限界温度は32℃より少し高い附近である。湿熱致死限界は50℃10分である。4.本病菌の発育に対する最適pHは4.8∿6.0の間にある。pH10.0附近では全然発育しない。5.本病菌は分離当時馬鈴薯煎汁寒天培地上で分生胞子堆の形成をしたが, その後形成を見ない。ところが紫外線を10分∿90分間照射した場合に, その無照射面に分生胞子堆の形成を見た。此の時は有色2細胞のが少く, 3細胞のが非常に増加していた。6.アラカシ, カシワ, クリ, スギ, チヤ, ビワ等に対する菌糸による接種試験では, 有傷区全部が陽性であつたが, カネ, イチヂク等は有傷, 無傷共に陰性であつた。7.本病害を学界未知のものと見做し, 「輪紋葉枯病」と命名し, その病原菌の学名をPestalotia kasagi ensis YEH et KATSURA sp. nov.とする。The authors founded a new disease of leaf on Quercus glauca THUNB., it caused by Pestalotia sp., and these speciemens were collected at Kasagicho prefectural Kyoto (Nov. 1956.), at Tokuzentani Sakyoku Kyoto (Dec. 1956.), at valley of Suwayama of Kobe (Mar. 1957.), at Takagamine Kitaku Kyoto (Nov. 1958.). This report was described with a morphological, physiological characters and the results of inoculation experiments of the causal fungus. The acervulus was formed in the ring spot on the epydermis of leaves, the conidia have brownish two cells at middle, rarely have three cells, and the flagella have length of almost two times to the conidia. On the potato agar medium the fungus formed hard conidial mass after culture for 20∿25 days only on cultures in short period since the fungus were isolate from the host, however, it did not form at all subcultures on the media used experiment thereafter, but it formed again on the culture of non-radiation side that perhaps received diffuse ray. The diffuse ray occurred when a half part of the cultures were radiated with ultora-violet ray. This result is only once experiment, so it is necessary reexperiment. The optimum temperature of growth to the fungus mycelium on potato agar medium seemed at about 24℃, and leathal temperature of the mycelium was at 50℃ for 10 minutes in water bath. On the pH of the medium the mycelium growth seemed vigorous at 4.8∿6.0. In the inoculation experiments mycelium of the causal fungus showed all positive only wounded leaves by needle on Quercus glauca THUNB., Q. dentata THUNB., Castanea pubinervis SCHNEID., Cryptomeria japonica D. DON., Theae sinensis L., Eriobotrya japonica L., but on the Diospyros Kaki THUNB., Ficus Carica L. showed all not phathogenicity. The authors named "Ring spot blight of Quercus glauca THUNB." and determined its species name as "Pestalotia kasagiensis YEH et KATSURA sp. nov.

イチジクを侵す疫病菌 2 種の比較(農学部門)

筆者らがイチジク疫病の罹病果から分離した菌(P_1), 筆者らの研究室に保存するカンキツ褐色腐敗病菌(C_1)の両種と, カリフォルニヤ大学から分譲されたPhytophthora palmivora (P_2), P. citrophthora (C_2)の4種を供試して, 生理的, 形態的性質および病原性について比較研究を行なった。供試4種菌について, それぞれの発育適温, 発育最高限界温度, 培地上の菌の発育, 培地上の各器官形成, 遊走子のうおよび厚膜胞子の形態, イチジク果実および葉に対する病原性などについて実験観察した結果, ほとんどの場合においてP_1とP_2,C_1とC_2はそれぞれ非常によく類似しているが, PとCとは種々の点で異なっていることを明らかにすることができた。以上の結果からP_1は明らかにP. palmivoraと同定されるし, C_2はP. citrophthoraと確認された。さらにイチジク疫病の特長である果実の白粉状のかびは, P. palmivoraによって接種された場合にのみ観察され, P. citrophthoraによってはかかる病状は起ることがなかった。またイチジクに対する病原性はP. palmivoraの方がはるかに強く, P. citrophthoraの病原性はかなり弱い。したがって病名のイチジク疫病の病原菌に対してはP. palmivora Butlerを当てるのが正しいと考える。To identify the Phytophthora species, isolate P_1,causal fungus of the white powdery rot of fig fruit, three isolates (P_2,C_1 and C_2) were compared with P_1 for their morphological and physiological characters and pathogenicity to fig, Ficus carica L. The isolates P_2 and C_2 were sent to us from University of California, Riverside, and had been identified to be Phytophthora palmivora and P. citrophthora respectively. All the date shown in this paper indicate that the isolate P_1 is P. palmivora and C_1 is P. citrophthora. The isolates P_1 and P_2 differed from the isolates C_1 and C_2 in many respects, especially in the symptoms on fig fruits : P. palmivora caused white powdery rot and formed abundant zoosporangia on the lesion of the infected fruit, while P. citrophthora incited brown rot forming a little or no zoosporangia on the infected fruits. P. palmivora was much more virulent against fig fruits and leaves than P. citrophthora. The present result therefore does not support the notion that P. citrophthora is the causal fungus of the white rot of fig fruit, but clearly shows that P. palmivora is responsible for the white powdery rot. Nevertheless, P. citrophthora could also be a causal fungus of fig diseases. We express our sincere thanks to Professor G. A. Zentmyer of University of California for his generous supply of the isolates of Phytophthora

Phytophthora capsici Leonian 菌の被のう胞子の発芽過程における核現象(農学部門)

本報告はPhytophthora capsiciの被のう胞子, その発芽過程および小遊走子のう形成に至る間の現象, とくに核現象について研究を行なったものである。被のう胞子の発芽は20°∿28℃で良好であり, その発芽管の伸長は24℃が最適である。被のう胞子の発芽に際し, 原形質は発芽管ないし小遊走子のう内へ流動移行するが, 栄養を補う以前には原形質量の増加は認められない。遊走子の核は1つである。しかし被のう胞子が発芽過程に移る際に, 被のう胞子内で核分裂がはじまるものと, 発芽管の頸部で核分裂がおこるものとが認められるが, 発芽管の伸長とともに引続き発芽管内で核分裂が行なわれる。発芽管内の核分裂は32°, 24°, 20℃の順に早く行なわれるが, いずれの温度でも18時間後には平均8核になる。小遊走子のうは比較的高温においてよく形成し, その形成初期から成熟期前にかけて核数は増加し, 約3∿4個程度に達するが, 成熟期に達してのちは核数が減少し, ついに1核になる。この1核になった時期は小遊走子のうの発芽に移る時期とよく一致する。The germination of cystospore and the formation of miniature sporangium of Phytophthora capsici Leonian have been studied with special emphasis on the nuclear phenomena in those processes. The cystospore germinated in the temperature range of 20°∿25℃, but the germ tube elongation was best demonstrated at 24℃. On cystospore germination cytoplasmic contents were translocated to the germ tube and then to the miniature sporangium formed on the tip of the germ tube or its branch. No increment in the cytoplasmic volume was observed if nutrient was deprived of the germination medium. Zoospore and encysted zoospore have one nucleus. The nuclear division was observed to be initiated either in the cystospore or in the constricted part of the germ tube. In either case divisions were continued in the germ tube as it elongated. The time of division cycle seemed to be dependent on temperature. It was shortest at 32℃ followed by 24℃ and 20℃ in the order. The number of nuclei, however, reached to 8 in average after 18 hrs incubation at any temperature tested. Relatively higher temperature seemes to be favorable for the formation of miniature sporangia. Number of nuclei in the miniature sporangia increased to 3 or 4 in the early stage of their formation, but it decreased as the sporangia grew to the maturity, finally becomming to one. Judging from the time sequence, germination of miniature sporangia seemes to be initiated as soon as number of nucleus decreased to one

Phytophthora porri FOISTER の厚膜胞子形成(農学部門)

本論文はユリ科植物の白色疫病を原因するPhytophthora porri FOISTERの厚膜胞子の形成について述べたものである。供試菌はチューリップ, ラッキョウ, タマネギの白色疫病罹病株からそれぞれ分離したものである。本病菌は各種培地上で菌糸に膨み(Swelling)を形成しやすいが, 厚膜胞子の形成は非常に少なく, しかも形成にやや時日を要することと, 膨みと厚膜胞子との区別がやや困難であるために観察しにくい。球形で菌糸に間生しばしば連生するものがあり, また頂生する。好適な環境状態の下で任意の部位から発芽管を出す。大きさは平均20.8μないし平均30.0μの直径を有し, 環境要因による大きさの変異が大きい。PDA培地の菌叢上に水を注ぎ, 浸水状態にするとともに, 培養温度を20℃から以下の低い温度に変温すると, 厚膜胞子の形成が良好である。液体培養した菌叢を水培養に移したものは, 厚膜胞子の形成があまり良好でなく, 形成にかなり時間がかかる。また厚膜胞子の形成は, 液体培地よりも固体培地の方がよい。General pattern of chlamydospore formation in Phytophthora porri Foister was elucidated with three isolates of the fungus, isolated respectively from tulip, scallion, and onion. The fungus, irrespective of isolates used, forms many swelling of mycelium but quite restricted number of chlamydospores when cultured on various kinds of culture media. The chlamydopores are formed after a prolonged incubation and they are spherical or ovoid in shape, formed single or crowded, terminal or intercalary, and are capable of germinating with a germ tube under the favorable environmental condition. The average size of chlamydospores was in the range of 20.8μ to 30.0μ in diameter depending on the isolate and environmental conditions employed. The chlamydospores are formed many when the colony on PDA plate was submerged in a small volume of water and incubated at the temperature below 20℃, while the same treatment of mycelial mat cultured in a liquid medium did not efficiently induce the chlamydospore formation. The use of agar medium is consequently recommended for the study of chlamydospore formation

カンキツ褐色腐敗病ならびに緑かび病の病徴進展機作の比較(農学部門)

ミカン果実を侵かすPhytophthora citrophthoraおよびPenicillium digitatumの示す病徴はきわめて対照的である。前者が果実を褐変せしめるが軟腐を起さないのに比して後者は変色はほとんど起らずいちじるしく軟腐せしめる。本研究はこの病徴に相違を来たす原因を明らかにするために行なったものである。P. citrophthoraは同じPhytophthora属でも, P. capsiciに較べて軟化酵素の活性は低く, またPen. digitatumよりも低い。両菌が寄主に侵入するとともに罹病部pHが低下し始め, 2-3日後にP. citrophthoraの軟化酵素の最適pH域の外に出てしまう。しかしPen. digitatumの軟化酵素の最適pH域は低いところにあるため軟化はさらに進行する。またミカン果皮中にP. citrophthoraの軟化酵素活性をいちじるしく阻害する物質が含まれているのと相まってミカン果実でP. citrophthoraによる軟化は進行しないものと考えられる。Pen. digitatumの軟化酵素はendopolygalacturonase (endo-PG)を, P. citrophthoraはendo-PGとともにexo-polygalacturonase (exo-PG)も分泌しているようである。pectin estrase (PE)およびtrans-eliminase (TE)活性は両菌ともにほとんどみとめられない。褐変原因と考えられるphenol類は果皮中にはchlorogenic acidのみしかみとめられなかったが, これは両菌の発育ならびにPG分泌に対してほとんど阻害を示さないようであった。解剖所見によっても褐変部位を越えてP. citrophthoraの菌糸が伸展していることが見られる。Among the Citrus diseases, the symptoms of the brown rot of fruit caused by Phytophthora citrophthora show remarkable contrast to that of the common green mold disease by Penicillium digitatum. The former fungus changed the host tissue to brown colour but didn\u27t macerate it, the latter didn\u27t change colour although marked maceration progressed. The difference of the mechanisms on the reaction of Citrus fruits against these two fungal infections were studied in this paper. To evaluate the macerating activity the discs of cucumber fruit and potato tuber were used. The macerating activity of the host-pathogen complex in the lesion reached a maximal peak at 3rd day after inoculation with P. citrophthora, but fell down during following several days. With Pen. digitatum, the maximal activity was continued over several days after that. Optimum pH range for the maceration was in 5-6 for Pen. digitatum and in 3-4 for P. citrophthora respectively and the activity of the former was higher than the latter. On the other hand, pH of the lesion formed by each pathogen began to drop from 3rd day after inoculation and then reached a stationary value, 3-4,at 5th day. In this pH range the macerating enzyme secreted from P. citrophthora didn\u27t show their activity, moreover the activity was inhibited by the extracts from the pericarp of Citrus fruit. The facts described above can explain some of the reasons by which soft rot didn\u27t developed in the case of the brown rot by P. citrophthora. Pen. digitatum have endo-PG, and P. citrophthora have endo- and exo-PG, but both fungi didn\u27t secret trans-eliminase