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標題: 臺灣水稻紋枯病菌Rhizoctonia solani AG-1 IA特性分析比較
Characterization and comparison of rice sheath blight pathogen Rhizoctonia solani AG-1 IA in Taiwan
作者: 方則淳
Fang, Che-Chun
Contributors: 陳隆鐘
植物病理學系所
關鍵字: 水稻紋枯病;Rhizoctonia solani AG-1 IA;病害檢定;表面覆膜技術;感染褥
rice sheath blight;Rhizoctonia solani AG-1 IA;disease assessment;surface membrane technique;infection cushion
日期: 2012
Issue Date: 2013-11-19 12:38:31 (UTC+8)
Publisher: 植物病理學系所
摘要: 水稻紋枯病是由絲核菌第一融合群亞群(Rhizoctonia solani AG-1 IA)所引起,主要發生在高溫高濕氣候的地區,於臺灣已為常見之本土性水稻病害。藉由了解水稻紋枯病菌其生長特性、菌核分佈及菌核大小等差異性,並進一步觀察對水稻品種之致病能力,再觀察病原菌感染構造,進行上述特性之比較分析。從臺灣各地收集之水稻紋枯病菌株,其生長速率介於0.37~1.95mm / hr,整體平均生長速率為1.5 mm / hr。各菌株之菌核直徑則介於0.089±0.021~0.244±0.074cm之間。菌落型態可依照菌落褐化程度、菌核排列形式及菌核數量大小等特性進行區分。菌核分佈形式可分為六類,而菌落依照褐化程度可分為微弱、普通及劇烈三種類型。菌株群中呈現最高之菌核量為每平方公分含1.768±0.038顆,最少則為0.078±0.059顆。將上述菌株生長特性與菌株來源區域之年均溫、年降雨進行配對後,發現菌絲生長速率與年均溫呈正相關,而菌核數量則與年雨量呈正相關,年雨量則與菌核大小關聯性不高,反之則與年均溫較有關聯。將水稻紋枯病菌接種於插秧後50天之臺南11號並於接種一個月後統計發病指數,各紋枯病菌株造成之病徵其平均高度介於41.8±0.44~59.5±0.52 cm之間,造成之相對病斑高度範圍為44.8~66%,造成之平均病害指數範圍為3~9級。各菌株之菌落色素深淺及生長速率與其造成之植株病斑高度呈正相關。利用半透膜覆蓋水瓊脂及稻稈煎汁瓊脂培養基,觀察接種水稻紋枯病菌株後的菌絲發展及感染構造之產生狀況。水瓊脂培養基處理中盤據效率差,鮮少發現任何分化的構造或典型的感染褥產生,而有少數葉狀附著器存在。水稻稻稈煎汁瓊脂培養基處理中可發現菌絲纏聚較茂密,少部分區域有不明顯的菌絲聚集,類似典型的感染構造。由於誘導效果不佳,因此直接覆蓋臺南11號水稻稻桿,接種後兩天可以發現隔著半透膜之稻桿位置上方的菌絲呈現高度聚集,和未接觸稻桿組織之半透膜區域菌絲形成明顯對比,又之後發現菌絲接觸稻稈的位置後皆會於上方形成菌絲聚集。而菌絲可以直接穿透半透膜的脆弱區域,並碰觸到寄主表面之後產生特化構造。於接種臺南11號稻叢進行發病觀察同時對病組織進行取樣以觀察感染構造。菌株間之感染構造皆為典型之感染褥,由菌絲分支聚集、交叉堆疊而成,另外也會發現聚集較不複雜,單一菌絲膨大且分支的小型感染構造,類似葉狀附著器。整體感染構造之呈現面積介於357.53~1696.97μm2,而每平方公厘之感染構造數目為35.62~118.98個。將上述個別項目之觀察數據與各菌株之平均發病指數進行關聯性分析,感染構造面積及單位面積感染構造數目與發病指數之間呈正相關。若藉由上述之相關性,進一步探討水稻紋枯病菌株接種不同齡期水稻稻株或不同接種方式所產生之發病情形,若能與一般抗性檢定之數據相關,則可幫助減少耗時及其他成本以幫助檢定。而各地區之水稻紋枯病菌其部分特性對於各地區環境相關,結合水稻紋枯病菌之生態性,進行水稻栽培方式之調整,期能對病害整合管理上提供參考。
Rice sheath blight disease caused by Rhizoctonia solani AG-1 IA always occur in the area with high temperature and moisture and has already become endemic in Taiwan. This study analyzed the difference and relationship of the morphology, mycelial growth, sclerotial arrangement, the virulence and infection structure. Rice sheath blight isolates collected in Taiwan showed the growth rate 0.37~1.95 mm / hr, and the average growth rate was 1.5mm/hr; the isolates showed the sclerotial diameter 0.089±0.021-0.244±0.074cm. The colony could be classified with three criteria including sclerotial number, sclerotial arrangement with 6 types, and the colony pigmentation that could be divided into weak, normal, and obvious levels. Sclerotial number produced by isolates ranges between 1.768±0.038-0.078±0.059 number / cm2. After comparing the characteristics of isolates with the environmental condition of collection source, mycelia growth rate shows the positive correlation with annual mean temperature, and sclerotial number shows the positive correlation with annual rainfall. However, the sclerotial diameter shows no correlation with annual rainfall, but with annual mean temperature. Inoculation to cultivar Tainan 11 with isolates was carried out for observation of the virulence and all isolates could cause the disease severity 3-9, with the average lesion height 41.8±0.44-59.5±0.52 cm and the relative lesion height 44.8~66%. The mycelia growth rate and the colony pigmentation show the positive correlation with the lesion height. Surface membrane technique was used to cover the water and rice sheath water extract agar medium for the comparison of infection structure induction, and the latter showed the better effect on colonization promotion, but the infection structure was not obvious and typical. By using the sterilized rice sheath tissue instead of the agar medium, the hyphal aggregation occurred on the location attached with rice sheath tissue, and may penetrated through the fragile part, then attach to the rice tissue surface. The mycelia differentiated following the attachment with tissue surface. The diseased tissue was sampled from the virulence test to Tainan 11 for direct observation of infection structure. All isolates showed the typical infection cushion and some swelling, curving hypha were investigated like the structure lobate appressoria. The area of infection structure ranged between 357.53-1696.97μm2 and the number of infection structure was 35.62~118.98 number / mm2. The area and the number of infection structure show the positive correlation with the disease severity. According to the relatedness analysis, different disease assessment for the resistance could be tested and confirmed the similarity and the trend with the standard rice cultivar evaluation of rice sheath blight resistance currently. And other relatedness of characteristics with environmental factors could be combined with the ecology of rice sheath blight pathogen and the rice crop system, for modifying the strategy and achieve integrated pest management.
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