条形柄锈菌小麦专化型小种CYR29有性自交及毒性与无毒性基因的遗传分析

由条形柄锈菌小麦专化型（小麦条锈菌）Puccinia striiformis f. sp. tritici引起的条锈病是小麦上重大的生物灾害,严重威胁小麦安全生产。应用抗病品种是防治小麦条锈病最为经济有效的措施,但是条锈菌毒性的频繁变异,常常导致品种抗病性丧失,从而引发条锈病新的大流行。有性生殖是条锈菌毒性变异的重要途径,本文通过对小麦条锈菌流行小种CYR29在转主寄主小檗上的自交研究了有性生殖与病菌毒性变异之间的关系。通过诱导CYR29单夏孢子菌系形成冬孢子、萌发产生的担孢子接种转主寄主小檗,使其完成有性过程,由此共获得81个自交后代,对有性后代群体S1和亲本菌系在20个含单个抗病基因的近等基因系鉴别寄主上进行毒性鉴定。S1群体和亲本在Yr5、Yr8、Yr10、Yr15、Yr24、Yr32、YrSP、YrTr1和Yr26上均为无毒性,在Yr1、Yr31、Yr44和YrTye上均为毒性。S1群体在Yr6、Yr7、Yr9、Yr17、Yr27、Yr43和YrExp2这7个位点上出现了毒性分离,表明亲本在这些位点为杂合。81个自交后代可分为24种毒性表型,其中1种表型与亲本毒性一致,含22个菌系;其余23种毒性表型与亲本存在差异,含59个菌系,毒性变异率高达72.8%,且发生变异的子代均比亲本毒性谱更宽。结果表明该小种经过有性过程后产生了毒性增强的新菌系,进一步证实有性生殖是导致小麦条锈菌具有较高遗传多样性的原因之一。

Sexual selfing and genetic analysis of virulent and avirulent genes of isolate CYR29 of Puccinia striiformis f.sp.tritici

Stripe rust disease caused by Puccinia striiformis f. sp. tritici (Pst) is an important biological disaster on wheat, which seriously threatens the safety of wheat production. Application of resistant cultivars is the most economical and effective approach to control wheat stripe rust. However, the frequent variation of the virulence of Pst causes rapid loss of resistance to wheat stripe rust, triggering a new pandemic of stripe rust. Sexual reproduction is an important way for the virulent variation of stripe rust. In the present study the relationship between virulence variation and sexual reproduction is investigated by means of self-cross of epidemic race CYR29 of Pst on alternate host Berberis shensiana. The teliospores derived from a single urediniospore of CYR29 isolate were used to produce basidiospores for inoculating B. shensiana to finish the sexual process. Eighty-one aecial selfed progenies and the parental isolate were tested on differential hosts including 20 wheat lines with single Yr genes. The progenies and parental isolates were all avirulent to Yr5, Yr8, Yr10, Yr15, Yr24, Yr32, YrSP, YrTr1, Yr26 and all virulent to Yr1, Yr31, Yr44 and YrTye. Different levels of segregation ratio were identified for Yr6, Yr7, Yr9, Yr17, Yr27, Yr43 and YrExp2, and the result indicated that the parental isolate was heterozygous at these loci. The eighty-one selfing progenies can be divided into 24 virulence phenotypes. One of the phenotypes which contains twenty-two progeny isolates was identical to the parental isolate, and the other twenty-three phenotypes which contains fifty-seven progeny isolates were different. The ratio of variation reached 72.8 percent. The variant progenies possess a larger virulence spectrum than the parent. The data revealed that new phenotypes could be acquired through sexual reproduction of CYR29. This proves ulteriorly that sexual reproduction is one of the reasons for high genetic diversity of Pst.