小麦抗病相关基因TaTGA2.2在小麦-条锈菌互作中的表达分析及功能研究

Characterization and Functional Analyses of Wheat Disease Resistance-Related Gene TaTGA2.2 in the Interaction Between Wheat and Stripe Rust

为了进一步解析小麦与条锈菌(Puccinia striiformis f.sp.tritici,Pst)互作中的抗病分子机制,在小麦-条锈菌互作的cDNA文库中分离得到一个编码bZIP类转录因子的小麦抗病相关基因TaTGA2.2。通过实时荧光定量PCR(Quantitative real-time PCR,qRT-PCR)以及病毒诱导的基因沉默技术(VIGS)对TaTGA2.2的表达模式及其在小麦与条锈菌互作中的功能进行了初步解析。结果表明,小麦TaTGA2.2基因全长1005 bp,编码334个氨基酸,具有bZIP保守结构域以及TGA转录因子类似结构域。进化树分析发现TaTGA2.2与一粒小麦中TGA蛋白近缘。拟南芥原生质体亚细胞定位发现TaTGA2.2分布在细胞核,酵母自激活实验表明TaTGA2.2蛋白N端具有转录激活活性。此外,TaTGA2.2受条锈菌诱导表达,且非亲和互作中的表达量较亲和互作明显增高。非生物胁迫处理中干旱、盐以及外源激素水杨酸(SA)和脱落酸(ABA)也能诱导TaTGA2.2上调表达。VIGS沉默TaTGA2.2基因后,发现接种条锈菌CYR23及CYR31后小麦的表型均无明显变化。另外,PR基因的表达量也无显著差异,表明植物中可能存在与TaTGA2.2功能冗余的TGA成员。

In order to further analyze the molecular mechanism of disease resistance in the interaction between wheat and Puccinia striiformis f.sp.tritici(Pst),a wheat disease-resistance gene TaTGA2.2,encoding a bZIP transcription factor,was isolated from the cDNA library of wheat-Pst interaction.Quantitative real-time PCR(qRT-PCR)and virus-induced gene silencing(VIGS)were used to preliminarily analyze the expression characteristics and function of TaTGA2.2.This study focused on the TaTGA2.2,which contains a 1005 bp open reading frame,encoding one class of bZIP transcription factor with 334 amino acids.Phylogenetic analysis revealed that TaTGA2.2 had the closest evolutionary distance from TmTGA.Arabidopsis protoplasts subcellular localization analysis found that TaTGA2.2 is distributed in the nucleus.Transcriptional activation analysis in yeast revealed that TaTGA2.2 exhibits transcriptional activity in its N-terminal.The level of TaTGA2.2 transcripts were up-regulated induced by Pst as well as drought and salt,but the level of expression was apparently higher in incompatible interaction than that in compatible interaction.Besides,the transcription of TaTGA2.2 was also induced by exogenous hormone SA and ABA.When knocked down TaTGA2.2 with VIGS system,there was no significant difference in phenotype,and the expression level of PR genes also did not change significantly.The results indicate that functional redundant TGA members with TaTGA2.2 may exist in wheat.