Genome-wide characterization of WRKY gene family in Helianthus annuus L. and their expression profiles under biotic and abiotic stresses

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background:</jats:bold> WRKY transcription factors play important roles in various physiological processes and stress responses in flowering plants. However, the information about WRKY genes in <jats:italic>Helianthus annuus</jats:italic> L. (common sunflower) is limited. <jats:bold>Results: </jats:bold>Ninety WRKY (<jats:italic>HaWRKY</jats:italic>) genes were identified and renamed according to their locations on chromosomes. Further phylogenetic analyses classified them into four main groups including a species-specific WKKY group and <jats:italic>HaWRKY</jats:italic> genes within same group or subgroup generally showed similar exon-intron structures and motif compositions. The tandem and segmental duplication possibly contributed to the diversity and expansion of <jats:italic>HaWRKY</jats:italic> gene families. Synteny analyses of sunflower WRKY genes provided deep insight to the evolution of <jats:italic>HaWRKY</jats:italic> genes. Transcriptomic and qRT-PCR analyses of <jats:italic>HaWRKY</jats:italic> genes displayed distinct expression patterns in different plant tissues, as well as under various abiotic and biotic stresses. <jats:bold>Conclusions: </jats:bold>Ninety WRKY (<jats:italic>HaWRKY</jats:italic>) genes were identified from <jats:italic>H. annuus</jats:italic> L. and classified into four groups. Structures of HaWRKY proteins and their evolutionary characteristics were also investigated. The characterization of <jats:italic>HaWRKY</jats:italic> genes and their expression profiles under biotic and abiotic stresses in this study provide a foundation for further functional analyses of these genes. Therefore, these functional genes related to increasing the plant tolerance or improving the crop quality, could be applied for the crop improvement..</jats:p>