Isolation and Expression Analysis of Drought-Induced Gene ZmCKS2 in Maize

In an earlier study, an expressed sequence tag (EST) from a drought-related suppression subtractive hybridization (SSH) library was obtained, which had a high similarity to AtCKS2 from Arabidopsis. To dissect the structure and expression characteristic of this EST, the cDNA homologous to CKS2 was isolated using in silico and homology-based cloning techniques, and which was designated ZmCKS2. ZmCKS2 has an open reading frame of 267 bp and encodes 88 amino acids. The deduced protein of ZmCKS2 is predicted to contain a cyclin-dependent kinase regulatory subunit (CKS) structural domain, which was highly conserved in eukaryotes kingdom. The promoter of ZmCKS2 (about 2 kb upstream of ZmCKS2) was predicted to contain important regulatory elements including core promoter elements and drought, high salt, coldness, abscisic acid (ABA), light regulation, copper, and oxygen-responsive elements. Real-time quantitative PCR (qRT-PCR) result revealed that ZmCKS2 had different expression patterns in different organs. It was highly expressed in ears, while its expression was very low in roots and leaves at seedling stage. qRT-PCR was also performed to investigate the expression profiles of ZmCKS2 under different abiotic stresses such as drought, low temperature, high salt, methyl jasmonate (MeJA), and exogenous ABA. Under drought or MeJA treatment, ZmCKS2 showed an up-regulated expression pattern. However, under cold or ABA treatment, this gene showed a down-regulation expression pattern. Under NaCl stress ZmCKS2 showed no obvious change. These results revealed that ZmCKS2 might be involved in multiple pathways of plants responding to different environmental conditions.

摘要在本实验室前期研究的干旱胁迫相关的抑制差减文库(SSH)中, 发现一个玉米干旱胁迫诱导表达的EST序列, 与拟南芥AtCKS2和AtCKS1基因有较高的同源性。应用生物信息学手段和同源克隆的方法, 分离得到该基因, 命名为ZmCKS2。序列分析表明该基因开放阅读框区267 bp, 编码88个氨基酸。ZmCKS2蛋白含有真核生物中高度保守的CKS (cyclin-dependent kinase regulatory subunit)结构域。应用在线分析软件预测该基因上游2 kb序列表明, 该序列具有启动子的核心序列和增强子序列, 同时还具有与干旱等多种逆境胁迫相关的调控序列。应用实时荧光定量PCR分析表明该基因在幼穗中表达量最高, 且受干旱和MeJA诱导上调表达, 受低温和外源ABA诱导下调表达。