Abstract
Background: WRKY transcription factors are a superfamily of regulators involved in diverse biological processes and stress responses in plants. However, knowledge is limited for WRKY family in camelina (Camelina sativa), an important Brassicaceae oil crop with strong tolerance against various stresses. Here, genome-wide characterization of WRKY proteins is performed to examine their gene-structures, phylogenetics, expressions, conserved motif organizations, and functional annotation to identify candidate WRKYs mediating regulation of stress resistance in camelina.Results: Total of 242 CsWRKY proteins encoded by 224 gene loci distributed uneven on chromosomes were identified, and classified into three groups via phylogenetic analysis according to their WRKY domains and zinc finger motifs. 15 CsWRKY gene loci generated 33 spliced variants. Orthologous WRKY gene pairs were identified, with 173 pairs in C. sativa and Arabidopsis genomes as well as 282 pairs for C. sativa and B. napus, respectively. 137 segmental duplication events were observed but no tandem duplication in camelina genome. Ten major conserved motifs were examined, with WRKYGQK as the most conserved and several variants existed in many CsWRKYs. Expression analysis revealed that half more CsWRKY genes were expressed constitutively, and a set of them had a tissue-specific expression. Notably, 11 CsWRKY genes exhibited significantly expression changes in plant seedlings under cold, salt, and drought stress, respectively, having preferentially inducible expression pattern in response to the stress.Conclusions: The present described a detail analysis of CsWRKY gen family and their expression profiled in twelve tissues and under several stress conditions. Segmental duplication is the major force for large expansion of this gene family, and a strong purifying pressure happened for CsWRKY proteins evolutionally. CsWRKY proteins play important roles for plant development, with differential functions in different tissues. Exceptionally, eleven CsWRKYs, particularly five alternative spliced isoforms were found to be the key players possibly in mediating plant response to various stresses. Overall, our results provide a foundation for understanding roles of CsWRKYs and the precise mechanism through which CsWRKYs regulate high stress resistance to stress as well as development of stress tolerance cultivars for Cruciferae crops.
Genome-wide identification and functional characterization of Camelina sativa WRKY gene family in response to abiotic stress
