效应因子PsCRN77基因在本氏烟中的表达降低其对寄生疫霉的抗性

Expression of an effector gene PsCRN77 decreases Nicotiana benthamiana resistance to oomycete pathogen Phytophthora parasitica

CRN(Crinkler)是一类疫霉菌胞内效应因子,绝大多数CRN的功能和作用机制尚不明确。本研究利用农杆菌介导的瞬时表达技术,发现大豆疫霉效应因子PsC RN77可以在本氏烟中抑制激发子诱导的细胞死亡。接种分析表明在本氏烟中表达该效应因子基因可以促进寄生疫霉的侵染。定量RT-PCR结果显示在本氏烟中表达PsCRN77可以负调控水杨酸信号途径标记基因PRb-1b的表达,正调控茉莉酸信号途径标记基因LOX的表达。进一步通过DAB染色表明,与表达GFP对照相比,表达PsCRN77可以降低疫霉菌侵染后本氏烟中的活性氧积累。以上结果表明PsCRN77是一个毒性效应因子,可以通过影响激素抗性信号途径和活性氧积累干扰植物的防卫反应,促进病原菌的侵染。该研究为认识疫霉菌的致病机制提供了线索。

CRNs （Crinklers） are a group of cytoplasmic effectors in Phytophthora. However, functions and mechanisms of most CRNs are largely unknown. Here we show that the effector PsCRN77 from P. sojae can suppress elicitor-triggered cell death in Nicotiana benthamiana by using Agrobacterium-mediated transient expression approach. Inoculation assay showed that expression of PsCRN77 promoted P. parasitica infection. The quantitative RT-PCR results demonstrated that PsCRN77 negatively regulated expression of the salicylic acid signaling marker gene PRb-1b, and positively regulated expression of the jasmonic acid signaling maker gene LOX. DAB staining result showed that PsCRN77 expression decreased H2O2accumulation in P. parasitica-challenged N. benthamiana compared to GFP control. These results together suggested that PsCRN77 is a virulence effector and may promote plant susceptibility by interfering with hormone signaling and reactive oxygen species accumulation. This study provides clues for understanding the pathogenesis of Phytophthora pathogens.