水稻Xa1基因启动子的克隆及功能分析

Xa1是一个能对日本白叶枯病优势小种(小种1号)产生专化性抗性的R基因,虽已有该基因克隆、表达和功能方面的研究,但对其表达调控分子机制还不很清楚。本研究利用Xa1启动子与GUS报告基因的转基因T1株系,研究了Xa1启动子的时空表达及对不同外源激素的应答特征。结果表明,Xa1启动子驱动的GUS基因在水稻根中的表达量明显高于茎和叶,且在根部的中柱区GUS的表达量明显高于周围组织;在外源MeJA作用下GUS的表达显著增强,在SA和ABA处理下也有一定程度的增强,这些结果暗示Xa1的抗病作用与其在根系中柱的组织特异性表达存在一定的相关性,MeJA对Xa1启动子的活性起重要的调控作用。

Cloning and Functional Analysis of Rice Xa1 Gene Promoter

A bacterial blight resistance gene, Xa1, confers a high level of specific resistance to race 1 strains of Xoo in Japan. The molecular mechanism of expression regulation of Xa1 is obscure, though it was cloned and its expression and function was studied. In this paper, we analyzed the temporal and spatial expression and different hormones inducibility of Xa1 promoter, in the T1 generation of transgenic rice by fusing Xa1 promoter with a reporter gene GUS. The results indicated that GUS expression driven by Xa1 promoter in roots was higher than in stems and leaves, especially strong in filling post of roots. GUS expression was increased significantly treated by MeJA, and increased slightly by SA and ABA. These results suggested that the resistance of Xa1 was related to its tissue-specific expression in filling post. MeJA played a critical role in activity regulation of Xa1 promoter.