番茄冷诱导基因SlCMYB1的克隆及其在水稻中异源表达研究

Cloning of Cold-Inducible Gene SlCMYB1 and Its Heterologous Expression in Rice

从番茄中克隆了一个编码MYB转录因子家族R2R3-MYB亚类基因SlCMYB1。不同逆境胁迫下的表达模式分析结果表明,该基因受低温、高盐、干旱和ABA胁迫诱导表达。洋葱表皮亚细胞定位研究表明,SlCMYB1为核定位蛋白。为深入了解SlCMYB1基因与非生物逆境应答的关系,我们构建了SlCMYB1基因过表达载体来转化水稻,获得了16个转基因水稻株系。SlCMYB1在水稻中异源表达能显著提高转基因水稻植株的苗期抗冷性,增加脯氨酸合成的关键酶基因OsP5CS1,膜转运蛋白基因OsWCOR413等低温胁迫应答基因的表达水平,这暗示着SlCMYB1与OsP5CS1、OsWCOR413基因处于同一低温调控信号转导路径。本研究结果为通过遗传工程操控低温信号通路的方法改良冷敏感植物抗冷性提供了理论基础。

We isolated a cDNA clone, designated SlCMYB1 （for Solanum lycopersicum Cold MYB1）, from tomato by analyzing the previous microarray data of the low temperature transcriptome of tomato. SlCMYB1 encodes a R2R3-MYB family gene, which contains a conserved DNA-binding domain composed of two repeat motifs. The SlCMYB1-GFP fusion protein was localiz ed to the nucleus in a transient expression assay. Expression of SlCMYB1 was not only strongly induced by cold and salt, but also by dehydration and abscisic acid （ABA）. To understand function of SlCMYB1 in crop plants under stress conditions, we generated transgenic plants in rice over-expressing SlCMYB1 under control of the CaMV 35S promoter. Preliminary results showed that overexpression of SlCMYB1 in rice induced constitutive expression of the cold-responsive gene OsP5CS1 and OsWCOR413 and might be conferred enhanced tolerance to cold treatments for non-acclimated transgenic plants, compared with wild type plants. Our data suggest that SlCMYB1 might play an important role in plant responses to cold stress by regulating cold-responsive gene expression and might be a useful gene for improving cold tolerance in crop plants.