高温高湿下CaRPT2在辣椒抗青枯病中的作用

Role of CaRPT2 in the resistance of pepper to bacterial wilt under high-temperature-high-humidity

[目的]青枯病是辣椒生产中主要的土传病害,在高温高湿下发病尤为严重。研究CaRPT2在高温高湿下辣椒应答青枯菌侵染过程中的作用,为开展辣椒抗青枯病遗传改良提供依据。[方法]以中抗青枯病辣椒自交系植株(HN42)与本氏烟草为试验材料,从辣椒叶片cDNA文库中克隆出NRL蛋白家族成员CaRPT2,对其进行同源比对和进化树分析,并通过瞬时过表达、亚细胞定位以及荧光定量PCR等技术研究CaRPT2在高温高湿下辣椒应答青枯菌侵染过程中的作用。[结果]CaRPT2的氨基酸序列与其他物种中的直系同源基因有着较高的同源性,CaRPT2蛋白定位在本氏烟草叶片的细胞质与细胞膜中,CaRPT2转录水平受高温高湿条件下青枯菌侵染的诱导表达,且在辣椒叶片中瞬时过表达CaRPT2,可显著诱导高温高湿下特异性抗病基因CaMgst3的转录激活。[结论]CaRPT2在高温高湿下辣椒应答青枯菌侵染过程中起正调节作用,可为进一步阐明RPT2基因在植物抗病中的功能提供参考。

[Purpose]Bacterial wilt caused by Ralstonia solanacearum is the main soil-borne disease in pepper production especially under high-temperature-high-humidity(HTHH).Study on the role of CaRPT2,a member of NRL protein family,in response to bacterial wilt infection under HTHH will benefit the genetic improvement of pepper.[Method]CaRPT2 was cloned from the leave cDNA library of HN42,a pepper inbred line with medium resistance to bacterial wilt,for homology comparison and phylogenetic tree analysis.And its role in pepper response to bacterial wilt infection under HTHH was studied by transient overexpression,subcellular localization and quantitative real-time PCR.[Result]The amino acid sequence of CaRPT2 in pepper was highly homologous to that of other species.CaRPT2 protein was located in the cytoplasm and cell membrane of Nicotiana benthamiana leaves.Under HTHH,transcription level of CaRPT2 was induced by R.solanacearum infection,and transient overexpression of CaRPT2 in pepper leave can significantly induce the transcriptional activation of disease resistance gene CaMgst3.[Conclusion]CaRPT2 acted positively in pepper immunity against R.solanacearum infection under HTHH,which provided theoretical guidance for further unraveling the function of plant RPT2 in plant immunity.