WRKY gene family expansion may arise from whole-genome duplication events, rather than from genome size, given that Selleckchem Caspase inhibitor the grapevine genome has not undergone recent genome duplication [48]. The Populus genome has undergone salicoid duplication (p event) [47] and [49], duplication events (β, α) have occurred in Arabidopsis and Gossypium, and Gossypium has undergone one more duplication event than Arabidopsis [49], [50] and [51]. The WRKY family, one of the most important transcription

factor families, regulates plant responses to various physiological processes, especially biotic and abiotic stresses [45] and [52]. Under salt stress, 26 WRKY genes were induced in Arabidopsis, based on comprehensive microarray analysis of the root transcriptome [53]. Of the 64 GmWRKY genes in soybean (Glycine max Merr.), 25 WRKY genes show differential expression in response to at least one abiotic treatment [15]. In rice, at least 54 WRKY genes respond to http://www.selleckchem.com/products/17-AAG(Geldanamycin).html abiotic stress [54]. In addition, the transcripts of 49 WRKY genes in Arabidopsis are expressed in response to bacterial infection and salicylic acid (SA) treatment [55]. In cotton, eight WRKY genes from different cotton species have previously been reported. GaWRKY1 participates

in the regulation of sesquiterpene biosynthesis in cotton, and GhWRKY3 may function in plant defense responses [19] and [56]. In the present study, we further identified 12 WRKY genes induced by salt stress, 16 induced by drought stress, and 14 induced in response to V. dahliae VD8 infection. As shown in Table 2, 11 WRKY genes were simultaneously induced by both drought and salt treatment, and six WRKY genes were simultaneously induced by drought, salt, and pathogen treatments. These results indicate that WRKY genes are important regulators in cotton stress responses. Notably, GhWRKY59 and GhWRKY80 exhibited sustained responses to V. dahliae inoculation from 48 h to 144 h. They are two of the six WRKY genes simultaneously induced by the three stressors (drought, salt, and V. dahliae inoculation). This finding indicates that GhWRKY59 and GhWRKY80 have multi-functional roles in stress

tolerance, and may potentially be applied in breeding for new cotton cultivars with increased stress resistance. Homologous Rebamipide genes from different plant species may play diverse roles. In Arabidopsis, WRKY genes (AtWRKY2, AtWRKY17, and AtWRKY33) are induced under NaCl treatment [53], [57] and [58], whereas AtWRKY63 may function in drought tolerance [59] and AtWRKY4 and AtWRKY60 function in plant responses to pathogens [7] and [60]. Genes homologous to all of these Arabidopsis WRKY genes except AtWRKY63 were identified in cotton. According to qRT-PCR analysis, WRKY22 and WRKY41, which are homologous to AtWRKY33 and AtWRKY17, respectively, were downregulated in response to NaCl treatment but significantly upregulated under drought treatment and post-inoculation.