荔枝霜疫霉中双组分信号转导系统的鉴定与表达分析

 荔枝霜疫霉(Peronophythora litchii)隶属于茸鞭生物界卵菌门疫霉属,由其引起的荔枝霜疫病是目前荔枝生产上一种最重要的病害,严重影响荔枝产量和鲜果品质。双组分信号途径在微生物中参与多种生命活动,但是在卵菌中尚未有相关研究。本研究通过生物信息学分析在荔枝霜疫霉中鉴定到2个杂合型组氨酸激酶(PlHK1、PlHK2)和1个响应调控蛋白(PlRR1)。其在卵菌中是保守存在的,并且与真菌在进化上相对独立。功能域分析表明,PlHK1和PlHK2的C端额外的融合了1个磷酸转移功能域(Hpt),这与真菌和植物的存在显著差异。转录分析表明3个基因在荔枝霜疫霉侵染阶段上调表达,并且响应渗透胁迫和氧化胁迫。以上结果揭示了双组分信号系统可能在疫霉致病过程中发挥重要作用。

Identification and expression analysis of two-component signaling system-related genes in Peronophythora litchi

Peronophythora litchi is an oomycete, a group that shares the kingdom Straminipila with photosynthetic algae, and causes severe economic losses due to litchi downy blight disease. Two-component signal (TCS) transduction system is involved in a variety of life activities of microbes, but to date, little is known about the TCS in oomycetes. In this study, bioinformatics approaches were used to search the TCS-related proteins in Pe. litchii based on known protein sequences, and two hybrid histidine kinases (PlHK1、PlHK2) and one response regulator (PlRR1) were identified. In the phylogenetic trees, the histidine kinases and the response regulator in oomycetes were conserved and distantly evolved compared to fungi. Conserved domain analysis indicated that the histidine kinases of Pe. litchii comprised a histidine-containing phosphotransfer protein (Hpt) domain within the C-terminus, which is significantly different from the orthologs of fungi. Furthermore, real-time PCR analysis revealed that three TCS-related genes from Pe. litchii showed a relatively higher expression level during infection stages and under H₂O₂ or osmotic stress. These results could provide basic data for clarifying the function of TCS in oomycetes.