Genome-wide identification and analysis of the trihelix transcription factors in sunflower

The trihelix genes encode plant-specific transcription factors, which play a vital role in plant morphological and developmental processes. However, information about the presence of trihelix genes in sunflower (Helianthus annuus L.) is scarce. Sunflower belongs to composite family and possesses strong drought and salt-alkali tolerance. In this study based on H. annuus genome data, we have identified and analyzed the trihelix genes with a complete description of their physical and chemical properties, phylogenetic relationships, motif composition, chromosome distribution, exonintron structure, cis-acting elements, and chromosome collinearity. In H. annuus, 31 full-length trihelix genes were identified and categorized into six subgroups (SIP, GT1, SH4, G delta, GT-gamma, and GT2). Multiple Em for motif elicitation (MEME), used for conservative motif analysis, identified 10 distinct motifs unevenly distributed on 31 trihelix genes. In addition to that, chromosome localization analysis showed the number and distribution of these trihelix genes on 17 chromosomes of H. annuus. Transcriptional structure analysis revealed the structure of introns and exons of different gene members. Furthermore, cis-element analysis identified 19 different types of cis-elements mainly related to abiotic stress, hormones, and growth and development of plant. Results of this study manifested novel insights into phylogenetic relationships and possible functions of H. annuus trihelix genes. Moreover, these findings can assist in future studies regarding specific physiological effects of H. annuus trihelix transcription factors.