小麦中小GTP结合蛋白基因TaRop2克隆及其表达分析

Cloning and Expression Analysis of TaRop2 Gene Encoding a Small GTP-binding Protein in Common Wheat

小GTP结合蛋白属于Rho家族,是植物特有的一类蛋白,在调控植物生长发育、抗逆和抗病过程中发挥着重要的作用。本研究通过筛选非亲和条锈菌小种CYR32侵染诱导的抗条锈病基因Yr5近等基因系(Taichung29*6/Yr5)c DNA文库,分离获得1个Rop家族基因的全长c DNA序列,命名为TaRop2(Triticum aestivum Rop2)。TaRop2包含1个591 bp的开放阅读框,预测编码含197个氨基酸残基的蛋白质,分子量为21.52 k D,理论等电点为9.49。通过在烟草表皮细胞瞬时表达,发现TaRop2分布于细胞核内和细胞膜上。RT-PCR分析结果表明,在高盐处理、非亲和条锈菌小种CYR32和亲和混合白粉菌菌株侵染时,TaRop2基因的表达水平升高,但被干旱、高温、低温和ABA处理抑制。说明TaRop2可能参与小麦防卫和抗逆反应过程。

The small GTP-binding proteins belonging to the Rho（ Rho-related proteins of plant） family are plant-specific and play important roles in regulating plant development,stress tolerance,and defense responses. In this study,a full-length c DNA sequence encoding a Rop protein was isolated by screening the c DNA library of the wheat stripe rust resistance gene Yr5 near-isogenic line（ Taichung29 ＊ 6 / Yr5） infected by an incompatible race CYR32 of Puccinia striiformis f. sp. tritici,and was designated TaRop2（ Triticum aestivum Rop2）. It contained a 591 bp open reading frame and was predicted to encode a 197 amino acids,which molecular weight was about 21. 52 k D with theoritical isoeletric point（ p I） was 9. 49. It was found that TaRop2 were mainly distributed in nuclus and membrane of the transformed tobacco epidermal cell through transient expression experiment. By RT-PCR expression analysis,TaRop2 expression level was increased after salt treatment or inoculation with incompatible race of stripe rust pathogen and compatible mixed powdery mildew strains,but suppressed by drought,heat,cold,and ABA.Based on these results,we proposed that TaRop2 might be involved in the wheat defence and stress responses.