谷子CBL基因鉴定及其在干旱、高盐胁迫下的表达分析

Identification of CBL Genes from Foxtail Millet (Setaria italica [L.] Beauv. ) and Its Expression under Drought and Salt Stresses

CBL/CIPK信号网络系统在植物对逆境应答过程中起重要作用。本文利用生物信息学方法从谷子基因组中鉴定出7个候选CBL基因，命名为SiCBL1~SiCBL7。分析表明谷子CBL基因在蛋白质序列和结构上非常保守，所有预测SiCBL基因都含有7~8个内含子，而且其外显子序列同源性很高并且大部分外显子含有相同的碱基数目。预测SiCBL基因均含有4个EF-Hand功能域而且相邻EF-Hand功能域之间的氨基酸数目非常保守。进化和聚类分析结果表明, CBL基因在陆生植物早期的进化过程中就已经存在，所有CBL基因被分为4个亚组。7个候选SiCBL基因中, 4个基因（SiCBL1、SiCBL2、SiCBL3和SiCBL5）受干旱胁迫诱导表达，3个（SiCBL1、SiCBL3和SiCBL7）受高盐胁迫诱导表达。SiCBL3基因在干旱胁迫下被强烈诱导可能意味着其在干旱应答中起重要作用。本文报道的谷子CBL基因丰富和完善了植物CBL成员, 为进一步研究CBL/CIPK网络系统在抗逆作物谷子逆境响应中的功能、机制奠定了基础。

CBL/CIPK signal network system plays an important role in plant stress response. In this study, we identified seven candidate CBL genes designated as SiCBL1–7 from foxtail millet （Setaria italica [L.] Beauv.） genome using bioinformatics methods. The distributions of the predicted foxtail millet CBL genes were uneven in the nine chromosomes. Sequence analysis showed that the protein sequences and structure of foxtail millet CBL genes were very conservative. All the putative CBL genes contained 7–8 introns. Most exons of those SiCBL genes contained the same base number and shared highly similar sequence identity. All foxtail millet CBL genes consisted of four EF-Hand functional domains and the distance between the EF-hand motifs was conservative. Evolutionary analysis revealed that the CBL genes existed in the early evolutionary stage of terrestrial plants and all CBL genes were divided into four subgroups. The expression patterns of those SiCBL genes under drought and salt stresses, were displayed by RT-PCR and the results showed that four SiCBL genes （SiCBL1, SiCBL2, SiCBL3,and SiCBL5） were strongly induced by drought and three SiCBL genes （SiCBL1, SiCBL3,and SiCBL7） were induced by salt stress. SiCBL3 maybe takes an important role in foxtail millet under drought because of its constitutive high level expression. Foxtail millet CBL genes reported in this study would enrich CBL members in plant kingdom and lay a foundation for studying the function and mechanisms of the CBL/CIPK network system response to stresses.