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

Abstract

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.