WRKY transcription factors play important roles in various physiological processes and stress responses in flowering plants. Sunflower (Helianthus annuusL.) is one of the important vegetable oil supplies in the world. However, the information aboutWRKYgenes in sunflower is limited. In this study, ninetyHaWRKYgenes 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. Besides,HaWRKYgenes within the same group or subgroup generally showed similar exon-intron structures and motif compositions. The gene duplication analysis showed that five pairs ofHaWRKYgenes (HaWRKY8/9,HaWRKY53/54,HaWRKY65/66,HaWRKY66/67andHaWRKY71/72) are tandem duplicated and fourHaWRKYgene pairs (HaWRKY15/82,HaWRKY25/65,HaWRKY28/55andHaWRKY50/53) are also identified as segmental duplication events, indicating that these duplication genes were contribute to the diversity and expansion ofHaWRKYgene families. The dN/dS ratio of these duplicated gene pairs were also calculated to understand the evolutionary constraints. In addition, synteny analyses of sunflowerWRKYgenes provided deep insight to the evolution ofHaWRKYgenes. Transcriptomic and qRT-PCR analyses ofHaWRKYgenes displayed distinct expression patterns in different plant tissues, as well as under various abiotic and biotic stresses, which provide a foundation for further functional analyses of these genes. Those functional genes related to stress tolerance and quality improvement could be applied in marker assisted breeding of the crop.

Editorial: Plant secondary metabolites and their effects on environmental adaptation based on functional genomics