玉米大斑菌致病毒素及其应用的初步研究

用大斑菌接种玉米幼苗和用大斑菌的培养滤液处理玉米根冠细胞的试验证明,大斑菌无论在体内或体外均能产生致病毒素。大斑菌不同菌株,1号和2号生理小种所产生的毒素作用强弱不同。在不含Ht_1基因的玉米1号小种(真16号菌株)的毒力明显强于2号小种(260号菌株)。大斑菌毒素制剂以病叶提取液的毒素作用最强。毒素的生物测定以根冠细胞测定法精确度高。用大斑菌接种玉米幼苗后形成的病斑大小和其毒素处理玉米离体根冠细胞的死亡率呈正相关,接种和处理含Ht_1基因的RB37Ht_1自交系的结果也相同。可见,应用大斑菌毒素可以代替大斑菌分生孢子接种玉米鉴别1号和2号生理小种和自交系的抗病性。

Preliminary Study on the Pathotoxin of Helminthosporium turcicum and Its Application

The results of inoculating corn seedeing with Helminthosporium turcicum and treating corn root cap cells with cultural filtrates of H. turcicum indicated that H.turcicum could produce pathotoxin either in vivo or in vitro. It was different in the efficiency of pathotoxin produced by race 1 and race 2 and by different isolates of same race 1. In this experiment, the efficiency of pathotoxin of race 1 (isolate No. 116) was obviously higher than that of race 2 (isolate No. 260) .The extracta from disease leaves had the strongest toxic effect among the different pathotoxin preparations of H.turcicum. The method of root cap cells was the most accurate and feasible one in the bioassay of pathotoxin. Firstly the lesion size induced by the pathogen had significant positive correlation with the reaction of corn root cap cells treated with theand 0.6251,respcctively). pathotoxin (the coefficient of correlation to race 1 and race 2 was 0.7752 And secondly, the reaction of inbred line RB37Ht_1,which bears gene root Htl to the pathogen showed the identical tendency to that of corn cap cells of same inbred treated with the pathotoxin. Therefore,it is possible to identify the physiological race 1 and race 2 of H.turcicum and to evaluate the resistance of corn inbreds only by using the pathotoxin instead of directly using the pathogen to inoculate corn plant.