(32(1):69-74)臺灣大豆銹病菌生理小種之鑑定

Soybean cvs. Ankur, TK 5, TN4, and P.I.’s 200492 and 230971 are suggested as differentials for race identification of Phakopsora pachyrhizi causing soybean rust in Taiwan. Three races of P. pachyrhizi, based on lesion type, were identified among 50 sngile uredial cultures from soybean leaves collected at five locations in Taiwan. Reaction was determined 14 days after inoculation on intact leaves on plants as well as on detached leaves. The distribution of the three races varied among locations. Common bean, cowpea, hyacinth bean, lima bean, pigeon pea and yam bean also were tested but because no difference in lesion type was observed they were not used as differentials. 從農試所、亞蔬中心、屏東、臺東及花蓮等五個地區之大豆銹病標本，利用離葉法在培養皿內進行接種源之純化與繁殖，每個地區各分得十個單一夏孢子堆來源之菌株，將五十個菌株之夏孢子懸浮液以離葉法分別接種在大豆鑑別品種 Ankur , TKS , TN4 , P . I . 200492 及 P . I . 230971 上，在室內（20-30 ℃ ）經過二星期後，按病斑型可區分為三個生理小種，此三個生理小種在植株上之反應與離葉法者相同，生理小種 1 在所有鑑別品種上產生感病型反應（ TAN ）；生理小種 2 僅在 P . I . 230971 上產生抗病型反應（ RB ），其餘均為感病型；生理小種 3 則僅在 P . I . 200492 上產生感病型反應，其餘為抗病型，此三個生理小種在五個地方之分佈不盡相同，臺東及花蓮未分離到生理小種 1 ；生理小種 2 在五個地區均有發現；生理小種 3 僅在花蓮分離到二菌株。 50 個菌株在菜豆（四季豆）及豆薯上均產生感病型反應，而在豇豆（ cowpea ），鵲豆（ hyacinth bean），皇帝豆（萊豆）及樹豆（P : geon pea ）上均產生抗病型反應，所以沒有被選用為鑑別品種，但在將來的試驗或世界其他地區也許可以利用

(35(1):81-93)Studies on Rusts of Maize

本省玉米銹病有普通型及南方型兩種。本研究之目的：一、繼續配合育種計畫進行抗病育種，協助檢定本所現有之種源（包括甜玉米及飼料玉米）及分離培育之材料對兩種銹病之抵抗性。二、探討溫度對夏胞子發芽及存活之影響以保存夏胞子做為抗病篩選時之接種源及其他研究之用。三、探討本省兩種玉米銹病菌是否有生理小種，做為抗病育種之指標。四、探討一些殺菌劑對兩種銹病的預防及治療效果做為藥劑防治之參考。抗病篩選仍採用幼苗測定法在溫室或生長箱內進行。七十四年度共測定甜玉米663個品系，其中有206個品系在三次接種試驗中都表現抗普通型銹病，但未發現有抗甫方型銹病者。七十五年度全省區域試驗飼料玉米22個品種（系）中有7個品系及對照品種臺農351號抗普通型銹病，但亦無抗南方型銹病者，僅有兩個中間型品系。夏胞子發芽試驗在2%水洋菜上進行，結果顯示溫度適合時夏胞子在二小時內就可發芽，普通型銹病菌（P. sorghi）從12至28℃發芽均良好，但以12及16℃最佳；南方型銹病菌（P. polysora）僅在24及28℃發芽較好。即手又發現P. polysora於低溫（16-20℃）所產生之夏胞子其發芽率顯然比高溫（24-30 ℃）所產生者為高。夏胞子存活試驗顯示P. sorghi在-40及-5℃保存150天仍有60~70%之發芽率，但P. polysora大約10天即完全失去發芽力。於28℃保存時P. sorghi大約30天但P. polysora亦約10天即完全失去發芽力。本試驗P. polysora夏胞子保存最好的溫度為20℃，但經過60天發芽率亦從55%降至14%，80天後即不發芽，所以P. sorghi夏胞子之保存較為容易，但P. polysora則有困難。從本省五個地區不定期前往採集銹病樣本，然後以離葉法在超甜玉米236號葉片上用無菌軟毛毛筆進行純化與繁殖，以獲取源自單一夏胞子堆之菌株供生理小種研究之用，結果顯示本省之P. sorghi沒有生理分化之現象，均屬於Race2，但P. polysora有13個生理小種，分別為Race3、4、5、6、7、8、9、10、11、12、13、15及16，其中Race3、5、10、15及16所佔比例較大為主要的生理小種，尤其是Race 16在272個菌株中佔29.4%比例最大。若依採集地而論，花蓮有9個生理小種其中主要為Race10及15，臺東有7個生理小種其中主要為Race16，屏東有8個生理小種其中主要為Race 16，雲林有7個生理小種其中主要為Race3、5、10及15，臺中有8個生理小種其中主要為Race 3及10。室內及田間藥劑試驗均顯示銹克優、賜加落、利總寧、克力保、殺可淨及殺普等對兩種銹病均有預防效果，但只有銹克優及賜加落之治療效果較佳，可使病斑枯乾並失去產胞能力；殺可淨及殺普之治療效果在病斑產胞前使用較佳。 Common rust (Puccinia sorghi) and southern rust (P. polysora) of maize were occurred in Taiwan. This research was attempted: (i) to screen germplasm and segregating breeding lines of dent and sweet corns for resistance to breed rust-resistant and high yield varieties; (ii) to study the effect of temperature on the germination and survival of uredospores for the manipulation of inoculum in the screening and for the preservation of uredospores for further studies; (iii) to explore the physiological races and their distribution, if any, of P. sorghi and P. polysora in Taiwan, and (iv) to evaluate the preventive and curative efficacy of some fungicides for the control of maize rusts. Corn seedlings with 3-4 leaves were inoculated with uredospore suspension in the greenhouse or growth chamber depending upon air temperatures. Of the 663 tested F8 and F4 lines of sweet corns from the crosses between Hawaii Super Sweet 9 and Suwan No. 1, two hundred and six lines were resistant to the infection by P. sorghi but they were all susceptible to P. polysora. Among the 22 varieties and/or lines used in the 1984-1985 regional yield trials, 7 lines and the check cv. Tainung 351 were resistant to P. sorghi but no one was resistant to P. polysora. The optimum temperatures for the uredospore germination of P. sorghi were observed between 12 and 28°C whereas P. polysora were found at 24 and 28°C. If the condition is appropriate, viable uredospores germinated in two hours. Higher percentage of germination was observed in the uredospores of P. polysora produced under cool temperatures (16-20°C) than that produced under warm temperatures (24-30°C). After 150 days stored at -40 and -5°C, 60-70% of the uredospores of P. sorghi were still able to germinate, however, P. polysora completely lost its germination ability after 10 days either at -40°C or-5°C. No viable uredospores were observed after 10 days for P. polysora and 30 days for P. sorghi at 28°C. The uredospore germination of P. polysora reduced from 55 to 14% after 60 days at 20°C which was the best temperature to preserve uredospores. Rust samples were collected from five corn-growing areas in Taiwan. Isolates from single uredium were purified and multiplied by the detached leaf method on the leaf segments of a susceptible sweet corn cv. Honey 236 in petri plates. Based on the reaction of the four differential varieties, all isolates of P. sorghi belonged to Race 2. However, 13 races of P. polysora were identified, they were Race 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, and 16. There were 8, 7, 8, 7, and 9 races of P. polysora were identified in the Taichung, Yuinlin, Pingtung, Taitung and Hualien collections, respectively, and the major races in the respective location were Race 3, 10; Race 5, 10, 15; Race 16; Race 16; and Race 10, 15. Among the fungicides tested in the greenhouse and field, Plantvax, Sicarol, Trimazone, Calixin-M, Sapxin and Saprol satisfactorily prevented corn plants from rust infection. However, only Plantvax and Sicarol were found with curative efficacy because they inhibited the development of rust pustules and/or killed the uredia in the lesions, then these uredia failed to produce uredospores. Sapxin and Saprol should be used in the early stage of infection before the production of uredospores