小檗NPR1在小麦条锈菌侵染过程中的表达特征

Expression pattern of barberry NPR1 during the infection of Puccinia striiformis f. sp. tritici

小檗是小麦条锈菌的转主寄主,自然条件下在小檗上进行有性生殖不仅是条锈菌毒性变异的重要途径,也为病害的流行提供了初侵染源。目前条锈菌与小麦互作已经有较为细致深入的研究,而条锈菌与小檗分子互作的研究未见报道。NPR1是植物调控防卫反应的一个关键基因,本研究克隆得到小檗NPR1基因(BhNPR1),并对BhNPR1及其下游病程相关基因的表达模式进行了分析。与小麦NPR1基因受条锈菌夏孢子侵染诱导不同,BhNPR1的表达水平在条锈菌担孢子侵染小檗过程中保持稳定。另外,条锈菌侵染小檗过程中NPR1下游的病程相关基因BhPR5和BvPDF1.2a的表达量变化也不明显,而BhPR1和BhPR2则显著上调表达。这些结果表明BhNPR1及多个病程相关基因不参与对条锈菌的防卫反应,这可能是导致小檗先天免疫缺陷而成为多种锈菌共同的转主寄主。

Barberry(Berberis,Linn)is the alternate host of Puccinia striiformis f.sp.tritici(Pst).Sexual reproduction of Pst on barberry under natural conditions not only causes virulence variation of the pathogen,but also provide primary inoculum for the diseases.The interaction between Pst and wheat has been studied in detail,while few studies have concerned the molecular interaction between Pst and barberry.NPR1 is a key gene involving plant defense response.In this study,NPR1 homologue in barberry(BhNPR1)was cloned and the expression levels of BhNPR1 and downstream pathogenesis-related genes(PRs)were analyzed.Unlike the induction of wheat NPR1 upon Pst urediospores infection,the expression level of BhNPR1 remained nearly constant during the infection of Pst basidiospores.In addition,the expression levels of BhPR5 and BvPDF1.2 a remain unchangeable also,while BhPR1 and BhPR2 were significantly up-regulated during the Pst infection.These results suggested that BhNPR1,BhPR5 and BvPDF1.2 a genes were not involved in defense response to stripe rust infection,which may cause defectives in barberry innate immune system and make barberry act as a common host for rust fungi.