GhWRKY3, a novel cotton (Gossypium hirsutum L.) WRKY gene, is involved in diverse stress responses

WRKY proteins play important roles in plant defense responses. In the present study, a novel WRKY gene, nominated as GhWRKY3, was isolated from cotton (Gossypium hirsutum L.). The full-length cDNA of GhWRKY3 is 1,705 bp in length and encodes a protein with 507 amino acids containing two typical WRKY domains and two zinc finger motifs. Amino acid sequence alignment revealed that GhWRKY3 shares a high degree of identity with other higher plant WRKY proteins. The subcellular localization assay indicated that GhWRKY3 is localized to the nucleus. Analysis of 5'-flanking region of GhWRKY3 revealed a group of putative cis-acting elements. The results of expression analysis indicated that GhWRKY3 is constitutively expressed in roots, stems and leaves. Semi-quantitative RT-PCR showed that GhWRKY3 is up-regulated by application of various phytohormones including salicylic acid (SA), methyl jasmonate (MeJA), abscisic acid (ABA), gibberellins (GAs) and ethylene (ET). Furthermore, the transcripts of GhWRKY3 are enhanced after infection with Rhizoctonia solani, Colletotrichum gossypii and Fusarium oxysporum f. sp. vasinfectum, respectively. Also, GhWRKY3 can be induced by wounding treatment, but not by cytokinin (6-benzylaminopurine, 6-BA), auxin analogue, drought, NaCl, and cold (4A degrees C). These data suggested that GhWRKY3 might play an important role in plant defense responses and fulfill a pivotal role in plant development.