芜菁WRKY groupⅢ家族鉴定及其对根肿病菌和激素的响应

Identification of WRKY groupⅢfamily and the response to Plasmodiophora Brassicae and hormone in turnip

WRKY转录因子是植物中特有的一类转录因子,已有研究表明WRKY groupⅢ家族众多基因在抵御生物胁迫的过程中发挥着重要的作用。为了解WRKY groupⅢ家族成员在芜菁根肿病抗性中的潜在功能,利用生物信息学分析方法,鉴定到21个候选WRKY groupⅢ家族基因,其不均匀分布于芜菁的9条染色体,编码蛋白包含258~916个不等的氨基酸残基,含0~8个不等的motif结构,大部分成员包含按顺序排列的motif 4-5-7/(8-2)-1-3。WRKY groupⅢ家族各成员启动子区域含有大量光、激素和逆境胁迫响应元件,在激素响应元件中以Me-JA最多。qRT-PCR结果显示WRKY groupⅢ家族基因可响应根肿病菌诱导,其中BrWRKY46-2、BrWRKY70-2在抗病材料根部表达量显著上调,感病材料中降低;经外源SA诱导后表达量上调,Me-JA诱导后下调,表现出相反的表达模式。亚细胞定位结果显示,BrWRKY46-2和BrWRKY70-2均定位于细胞核中。推测芜菁WRKY groupⅢ家族基因广泛参与了根肿菌响应过程,且BrWRKY46-2和BrWRKY70-2与芜菁品种抗病和感病密切相关并受SA和JA的强烈诱导,暗示其对根肿病具有重要调控作用,可作为进一步抗病研究和功能分析的候选基因。

The WRKY transcription factors are a class of plant-specific transcription factor family.Studies have shown that many genes in the WRKY group III family are involved in defense response of pathogenic bacteria and other biotic stress.To study potential function of turnip WRKY groupⅢfamily genes in clubroot disease resistance,21 WRKY genes were identified from the turnip genome using bioinformatics analysis and were distributed on the nine chromosomes.These WRKY proteins contain 258-916 amino acid residues with motif quantity ranging from 0-8,and most of them contain a motif structure with the sequence 4-5-7/(8-2)-1-3.Ana-lysis of cis-acting elements in promoter regions of WRKY groupⅢfamily gene found that there were a large number of light,hormone and stress responsive elements.Among hormone-responsive elements,Me-JA had the largest number.qPCR analysis showed that WRKY groupⅢfamily genes could respond to the induction of Plasmodiophora brassicae.Among them,BrWRKY46-2 and BrWRKY70-2 showed opposite patterns of up-and down-regulated expression in resistant and susceptible materials,respectively.The expression levels of BrWRKY46-2 and three BrWRKY70s were significantly down-regulated after exogenous SA induction,and were significantly down-regulated after MeJA induction.Subcellular localization showed that two genes,BrWRKY46-2 and BrWRKY70-2,mainly located in the nucleus.The WRKY groupⅢfamily genes in turnip were widely involved in the response process under P.brassicae stress.BrWRKY46-2 and BrWRKY70-2 genes were closely related to the resistance and susceptibility of turnip varieties and were induced by SA and JA.The above results imply that WRKY transcription factors have regulatory effects on clubroot resistance,and can be used as candidate genes for further needed on disease resistance and functional analysis.