利用真菌蛋白激活子防治白菜立枯絲核病

Reduction of Rhizoctonia damping-off in Chinese cabbage seedlings by fungal protein

將12菌株的鏈格孢屬（Genus Alternaria）真菌，逐一純化它們的總量蛋白後，分別測試各總蛋白促進白菜生長及減少病害發生的效果，結果發現部分菌株的總量蛋白質具有促進植物生長、刺激根系伸長及側根形成的功效外，尚可減少立枯絲核菌（Rhizoctonia solani）引起苗立枯病的罹病率。由山櫻花分離的APR01菌株真菌蛋白可顯著降低白菜苗立枯病的發生率達30％以上。依據產孢方式、孢子形態及rDNA ITS的序列分析，我們將APR01菌株鑑定為Alternaria tenuissima。分析APR01菌株之總量蛋白的抑菌活性，發現其無法有效抑制立枯絲核菌的菌絲生長。研究結果顯示APR01的總量蛋白分子量大於10 kDa者，具有減少苗立枯病發生的效果;然而其分子量小於10 kDa者，卻不具有抑病的功效。將APR01菌株之總量蛋白加熱處理，達50℃以上時，其抑制苗立枯病發生的能力幾乎完全喪失，顯示其抑病的主要成分可能是酵素或為熱敏感蛋白質。歸言之，本研究的結果顯示真菌蛋白有可能經由誘導植物防禦機制的啟動，進而有效降低作物土壤媒病害的發生。

"Total proteins were purified from 12 Alternaria species and tested for their ability to promote growth and disease reduction in Chinese cabbage. Our results indicated that proteins purified from some but not all Alternaria spp. were capable of promoting plant growth, stimulating root elongation and the formation of lateral roots, and reducing damping-off incidence caused by Rhizoctonia solani. Proteins purified from a cherry isolate designated APR01 exhibited most promising results in suppressing damping-off by 30%. APR01 isolate was identified as A. tenuissima based on cultural and morphological characteristics and sequence analysis of rDNA internal transcribed spacer (ITS). In vitro assays revealed no fungistatic activity of APR01 protein against R. solani. APR01 proteins with M.W. greater than 10 kDa displayed ability to reduce R. solani damping-off, whereas proteins M.W. less than 10 kDa had no effects. APR01 proteins heated at temperatures higher than 50°C completely or nearly abolished the ability to reduce disease, indicating that the major components contributing to disease reduction could be enzymes or heat-labile proteins. Nonetheless, our studies have demonstrated the possibility of fungal proteins in the reduction of a soil-borne disease, likely via the induction of plant defense mechanisms."