Molecular characterization of the GH3 family in alfalfa under abiotic stress.

The phytohormone auxin plays a pivotal role in regulating plant growth, development, and abiotic stress responses by promptly controlling the expression of auxin response genes. The Gretchen Hagen3 (GH3) genes are a major early auxin response gene family that contribute to auxin homeostasis by conjugating excess auxins to amino acids. To our knowledge, a genome-wide investigation of the GH3 genes in alfalfa has never been reported. Here, we present a comprehensive bioinformatics analysis of the MsGH3 gene family, including chromosomal locations, phylogenetic relationships, gene structures, conserved motifs and Gene Ontology annotation. Interestingly, the analysis revealed 31 MsGH3 genes in the alfalfa genome. These genes were classified phylogenetically into the GH3-I, GH3-II, and GH3-III subgroups. Additionally, the data analysis showed that most MsGH3 genes are tissue specific and responsive to environmental stress-related hormones. Furthermore, the analysis of cis elements and potential biological functions revealed that the MsGH3 genes play potential roles in various stress responses. Notably, qRT-PCR results following exposure to high temperature, drought, and salt treatments demonstrated that most of the MsGH3 family genes, especially MsGH3-12, MsGH3-13, and MsGH3-15, play important roles in stress responses. These findings provide invaluable insight for future practical analyses and genetic improvement of alfalfa abiotic stress tolerance.