氮胁迫条件下稻瘟病菌分泌蛋白致病性分析

 以CH-63和TH-162个致病性差异的稻瘟病菌株为材料,在缺氮培养条件下进行液体培养。经培养2 d后,采用铵盐沉淀及透析纯化处理获得稻瘟病菌培养滤液中的分泌蛋白。分别采用致伤接种及浸泡处理对该蛋白作用水稻植株后的病理反应进行系统研究,结果表明经致伤接种的水稻叶片及茎杆接种斑处出现明显的坏死病斑,其病斑直径是对照的2~4倍。浸泡处理的水稻幼根出现严重褐化,植株生长矮小,株高仅为对照的1/2。对上述稻瘟病菌株分泌蛋白进行酶解处理后病症消失或减弱,进一步确证其为引起上述病理反应的主要因子。将该分泌蛋白接种24个水稻单基因系,接种后72 h根据病斑长度将24个IRRI水稻单基因系按抗、中、感病性状分组。对稻瘟病菌菌株CH-63和TH-16的缺氮分泌蛋白致病力强弱差异与菌丝块接种结果进行比较,结果表明CH-63致病力强于TH-16。

Pathogenicity analysis of secretory protein of the rice blast fungus under nitrogen starvation

The rice blast fungal strains CH-63 and TH-16 were cultivated in a liquid culture medium under nitrogen starvation. After 2 d of cultivation, the protein secreted from the fungal strains was extracted by ammonium sulfate sedimentation and purified by dialysis. The rice plant was infected with secreted protein through inoculation or soaking method. The necrotic lesion was observed in the rice leaf and stem at the inoculated position. The lesion diameter was 2 to 4 times larger than that of control. Soaking treatment resulted in severe browning rice radicle and it was only half hight of that of control. When inoculated rice plants were treated with protease K, the disease symptoms disappeared or weakened. This finding further confirmed that the secreted protein was the major pathogenicity factor. Twenty-four monogenic rice lines developed at International Rice Research Institute (IRRI) were inoculated with the secreted protein and then categorized into resistant, intermediate resistant, and susceptible groups based on the size of necrotic lesions observed on the rice leaf tissue after 72 h of inoculation. The pathogenicity of rice blast fungal strains CH-63 and TH-16 was compared and the CH-63 strain showed higher pathogenicity than the TH-16 strain.