拟南芥与大豆疫霉菌的非寄主互作及一个感病突变体的遗传分析

非寄主抗病性是一种普遍的自然现象，该文通过建立拟南芥．大豆疫霉菌（Arabidopsis thaliana—Phytophthora sojae）非寄主互作系统，筛选对大豆疫霉菌感病的拟南芥突变体，为研究植物对卵菌的非寄主抗病性遗传机制奠定基础。以大豆疫霉菌游动孢子接种拟南芥T—DNA插入突变体离体叶片，从代表12000个独立转化株系的40000株T3代T。DNA插入拟南芥突变体中获得一系列对大豆疫霉菌感病的突变体。其中突变体581-51感病性状表现稳定，离体叶片接菌后3天内出现明显的水渍状病斑，4—5天后产生大量卵孢子和／或孢子囊。细胞学观察发现有典型的吸器形成。Southern杂交和遗传分析结果表明，581—51突变体含有4个T-DNA插入事件，其感病性状可能由隐性单基因控制。

Nonhost Interaction of Phytophthora sojae and Arabidopsis thaliana and Genetic Analysis of a Susceptible Mutant

Phytophthora sojae and Arabidopsis thaliana were used in this study as a nonhost plant-oomycete interaction system to investigate the genetic basis of nonhost resistance against oomycete pathogens in plants.A collection of more than 40 000 T3 A.thaliana T-DNA mutant plants representing 12 000 independent insertion lines were screened by inoculating detached leaves with P.sojae zoospores,and the susceptible mutant was re-confirmed by pathogen inoculation and cytological characterization.A number of P.sojae-susceptible A.thaliana mutants were successfully obtained,and one of them,mutant 581-51,was shown to be stably susceptible to P.sojae infection.Water-soaked lesions formed on the detached leaves within 3 days,as did oospores and sporangia 4-5 days after inoculation with P.sojae zoospores.Cytological characterization revealed the formation of haustoria-like structures.Southern analysis showed the presence of four T-DNA insertion events in the mutant.Genetic analysis indicated that the susceptibility to infection by the nonhost pathogen P.sojae in the mutant 581-51 was likely controlled by a single recessive gene.