小麦对白粉菌的抗性和感病性的诱导

 用小麦白粉菌(Erysiphe graminis f.sp.tritici)的无毒和有毒菌株,以3种接种顺序:1.先接无毒菌株,间隔一定时间后,再接有毒菌株;2.无毒和有毒菌株同时接;3.和"1"相反,接种具有不同抗性基因的小麦品种的幼苗或叶段,以研究小麦对白粉菌的诱导抗性和诱导感病性。结果表明:先接无毒菌株诱导的抗性最强;后接无毒菌株或无毒、有毒菌株同时接,当诱导菌(inducer)的密度很高时,也可以诱导出抗性,但较微弱;诱导的抗性随诱导菌的密度增高而增强;一经诱导,抗性可在被诱导部位维持到第6天;所使用的3种接种顺序都可以诱导小麦对白粉菌产生感病性,但较之诱导的抗性弱得多;在抗病性的诱导中,存在着小麦品种与诱导菌,或诱导菌与挑战菌(challenger)之间的相互作用;一个无毒菌株可以通过诱导而获得在抗病品种上生长的毒性,但当缺少有毒菌株存在时,获得毒性即消失;没有发现所诱导的抗性具有系统传导性。

INDUCTON OF RESISTANCE AND SUSCEPTIBILITY TO POWDERY MILDEW IN WHEAT

Wheat varieties with different resistance genes were inoculated for the induction of resistance and susceptibility to mildew, with various sequences of non virulent and virulent isolates of Erysiphe graminis f.sp. tritici . The induced resistance was most pronounced when a non virulent isolate (inducer) was inoculated prior to a virulent isolate (challenger). Post inoculation with a non virulent isolate or simultaneous inoculation of the non virulent and virulent isolates may also induce the resistance but less pronounced, depending on the inducer densities. Increase of inoculum density of non virulent isolates (inducer) increased the amount of induced resistance, Once induced, the resistance was active up to 6 days, susceptibility was induced by all inoculation sequences used but the effect was much smaller than that of induced resistance. There exised variety inducer of inducer challenger intercations in the induction of resistance. Acquired virulence of a non virulent isolate growing on a resistant variety disappeared in the absence of the virulent isolate. No systemic effect of induced resistance was detected.