木薯赤霉素途径DELLA蛋白基因克隆及其对干旱胁迫的响应

Gene Cloning of DELLA Protein from Cassava and Its Expression Patterns Under Drought Stress

赤霉素(GA)信号转导途径是通过DELLA抑制蛋白来调控的。笔者利用拟南芥DELLA蛋白基因序列,通过电子克隆方法首次克隆了1个木薯DELLA蛋白基因,长度为1857bp,具有完整的蛋白编码框的cDNA序列,命名为MeGAI。生物信息学分析显示,该蛋白具有与拟南芥DELLA蛋白一样的保守结构域,如DELLA结构域、VHYNP结构域、POLY(S/T)结构域、核定位信号、VHVID结构域、亮氨酸结构域、GRAS结构域;该基因在干旱胁迫下的表达模式研究结果表明,该基因在干旱胁迫下是下调表达的;GA生物合成重要基因GA20-氧化酶基因在干旱胁迫下的表达模式研究结果表明,两者在干旱胁迫下的表达模式具有良好的相关性,这说明GA途径可能参与木薯抗旱机制。

The GA signaling pathway is regulated by the DELLA proteins. A cassava nucleotide with high sequence homology to Arabidopsis thaliana GAI （AtGAI） was identified in the JGI database with the NCBI BLAST program. This nucleotide, named MeGAI, has a full length of 1857 bp and contained genomic coding sequences. Sequence comparisons between the MeGAI sequence and all of DELLA proteins in Arabidopsis indicated that MeGAI also has similar conserved domains to the DELLA proteins of the Arabidopsis, such as DELLA domain, VHYNP domain, POLY （S/T） domain, NLS domain, VHVID domain, leu zipper domain, GRAS domain. All these domains indicted that MeGAI is an ortholog of AtGAI. Analysis of expression patterns of this gene in response to drought stress treatment showed that this gene is down regulated. Moreover, analysis of the expression patterns of the GA2Oox gene, a key gene on GA biosynthesis process, indicated that the GA20ox gene has similar expression patterns to MeGAI. All these resuhs give the clues to possible involvement of GA signal in resistance to drought stress.