title: The role of ZmWRKY4 in regulating maize antioxidant defense under cadmium stress.
abstract: WRKY transcription factors act as positive regulators in abiotic stress responses by activation of the cellular antioxidant systems. However, there are few reports on the response of WRKY genes to cadmium (Cd) stress. In this study, the role of maize ZmWRKY4 in regulating antioxidant enzymes in Cd stress was investigated. The results indicated that Cd induced up-regulation of the expression and the activities of ZmWRKY4 and superoxide dismutase (SOD) and ascorbate peroxidase (APX). Transient expression and RNA interference (RNAi) silencing of ZmWRKY4 in maize mesophyll protoplasts further revealed that ZmWRKY4 was required for the abscisic acid (ABA)-induced increase in expression and activity of SOD and APX. Overexpression of ZmWRKY4 in protoplasts upregulated the expression and the activities of antioxidant enzymes, whereas ABA induced increases in the expression and the activities of antioxidant enzymes were blocked by the RNAi silencing of ZmWRKY4. Bioinformatic analysis indicated that ZmSOD4 and ZmcAPX both harbored two W-boxes, binding motif for WRKY transcription factors, in their promoter region. Intriguingly, ZmWRKY4 belongs to group I WRKYs with two WRKY domains. Moreover, the synchronized expression patterns indicate that ZmWRKY4 might play a critical role in either regulating the ZmSOD4 and ZmcAPX expression or cooperating with them in response to stress and phytohormone.
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China.
authors.forename: Changyong
authors.initials: C
authors.lastname: Hong
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Cheng
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Zhang
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhu
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China.
authors.forename: Yahua
authors.initials: Y
authors.lastname: Chen
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China. Electronic address: tempo@njau.edu.cn.
authors.forename: Mingpu
authors.initials: M
authors.lastname: Tan
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D020816:Amino Acid Motifs; D000975:Antioxidants / Q000378:metabolism*; D060387:Ascorbate Peroxidases / Q000378:metabolism; D002104:Cadmium / Q000737:chemistry*; D002467:Cell Nucleus / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013312:Stress, Physiological; D013482:Superoxide Dismutase / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D015854:Up-Regulation; D003313:Zea mays / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D012330:RNA, Double-Stranded; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D002104:Cadmium; D000040:Abscisic Acid; D060387:Ascorbate Peroxidases; D013482:Superoxide Dismutase
keywords: Antioxidant enzymes; Cis-acting element; Protoplasts-based transient expression; Synchronized expression; Transcription factor