Whirly (Why) transcription factors in tomato (Solanum lycopersicum L.): genome-wide identification and transcriptional profiling under drought and salt stresses

Whirly (Why) transcription factor (TFs) constitute one of the important TF families which plays essential roles in plant metabolism to cope with environmental stresses. In the present study, Why genes were identified at genome-wide scale in tomato (Solanum lycopersicum), and bioinformatics analyses were implemented. Validation of Why genes expressions under drought and salt stresses were also performed using RT-qPCR. The analyses revealed the presence of two Why genes in tomato genome, SlWhy1 (Solyc05g007100.2.1) and SlWhy2 (Solyc11g044750.1.1). Both genes contained Whirly transcription factor domain structure (PF08536), and Why proteins were in basic character (pI >= 7). While the lengths of the proteins ranged from 268 to 236 amino acid residues for SlWhy1 and SlWhy2 respectively, exon numbers identified in both genes were seven. According to the digital expression data, SlWhy genes are expressed at medium level in different anatomical parts and developmental stages. In the promotor sequence analysis, 13 types of putative TF binding sites were identified, and the highest motif number was 46, found for GATA TF. Gene co-expression analyses revealed that complex networks for SlWhy genes, which are connected with various metabolic pathways. Based on the RT-qPCR data, both SlWhy1 and SlWhy2 genes were up-regulated under salt and drought stresses. 3D structure analyses revealed that SlWhy1 protein had a more diverged structure than SlWhy2 protein, based on their comparisons in Arabidopsis and potato. The results obtained in the present study could be a useful scientific basis for understanding Why genes in tomato and their functions under abiotic stress conditions.