Comprehensive analysis of HB-PHD transcription factors associated with drought and salt stresses in wheat

HB-PHD transcription factors play important roles in plant growth and development as well as stress response. However, comprehensive analysis of HB-PHD genes was not investigated in wheat. In this study, a total of nine TaHB-PHD genes were identified in wheat at the genome-wide level, and their physicochemical properties, evolutionary relationships, gene structures, cis -acting elements, expression patterns, downstream genes, and drought-resistant superior haplotypes were systematically analyzed. Phylogenetic analysis showed that HB-PHD proteins were divided into five subfamilies, and TaHB-PHD genes belonged to subfamilies Ⅰ,Ⅱ, and Ⅴ. The gene structures and conserved motifs of members in the same subfamily were highly conserved. Tissue expression analysis revealed that TaHB-PHD genes had the highest expression levels in roots and the lowest in leaves. Under drought stress, the cultivar-specific expression pattern was observed, all TaHB-PHD genes were down-regulated in drought-tolerant cultivar Giza168, and up-regulated in Chinese Spring and drought-sensitive cultivar Gemmiza10. Under salt stress, TaHB-PHD1-A/ B/ D and TaHB-PHD3-A/ B/ D were up-regulated, while the expression of TaHB-PHD2-A/ B/ D showed no obvious change. Prediction of downstream genes found that TaHB-PHDs could regulate various genes such as ribosomal RNA methyltransferase and histone acetyltransferase to participate in stress responses. Haplotype analysis indicated that TaHB-PHD3-D-Hap I was a drought-resistant superior haplotype. This study provides a theoretical basis and candidate genes for the functional verification of wheat TaHB-PHD genes and stress-resistant molecular breeding.