摘要： 本研究将小麦叶锈菌小种261,362和370组成两个或三个小种的4种组合,分别在抗病、慢锈和感病品种上进行7代的继代培养,利用鉴别寄主检查各小种在各代中所占的比例,以了解各类品种对小种组成能否起稳定化选择的作用.研究结果表明:高抗品种洛夫林10和洛夫林13不能起稳定化作用,慢锈品种冀麦3号、感病品种5389和东方红3号对某些小种组合能起稳定化作用,但对另一些小种组合则不能起稳定化作用.一个品种能否起稳定化作用,取决于寄主和病原物相互作用的专化性.在感病或慢锈品种上各小种在混合小种中的竞争力,表现在侵袭力而不是毒性的差别上.三个小种与上述三个品种互作,都明显地表现小种261的竞争力最强,362的次之,370的最弱.一般讲,品种对混合菌中小种竞争力相差大的就不能起稳定作用.分别用6068和山前麦作鉴别品种来检查各小种在继代培养的各代中所占的比例的结果不一致,这是由于各小种的侵袭力不同所致.这是侵袭力决定寄主和病原物相互作用的专化性的例证.

关键词: 小麦, 叶锈菌, 稳定化选择

Abstract: Four sets of combinations of two races and three races of p. recondita f sp. tritici were made by combining different races of 261, 362 and 370 an successively cultured respectively on resistant, susceptible and slow rusting varieties for seven generations to see if any variety has stabilizing effect.The results showed that the highly resistant varieties Lovrin 10 and Lov rin 13 had no stabilizing effect. Susceptible varieties 5389 and Dongfanghong 3 and slow rusting variety Jimai 3 had stabilizing effect on certain combinations of races, but had no such an effect on other combinations. This fact indicates that whether a variety has effect of stabilizing selection or no depends on specificity of interaction between host and pathogen.The competitive ability comparison between races in the mixture interacting with slow rusting and susceptible varieties showed that the aggressiveness of race 261 was the strongest, that of race 362 was the next andthat of race 370 was the weakest. Generally speaking, any variety will not have the stabilizing effect if it interacts with a mixture of races which has a great difference in aggressiveness between theraces.The results of using two differential hosts (6068 and Predgornar 2) to detect the frequency of occurrence of the relevant race in each generation of subculturing were different. This was due to the difference in aggressiveness of races. This case indicates that the apecificity of interaction between the host and pathogen is due to not the virulence but the aggressiveness of thepathogen.Curbing the shift of population of pathogen through diversification of slow rusting and resistant varieties and the effect of environmental factors on the study of stabilizing selection were "discussed.

Key words: Wheat, Puccinia recondita, Stabilizing selection