Genome-wide Identification and Functional Analysis of <i>Gretchen Hagen 3</i> Genes in Soybean Resistance to Cyst Nematodes

The <i>Gretchen Hagen 3</i> genes maintain endogenous hormone homeostasis by conjugating excess hormones with amino acids. Herein, we identified the members of the GH3 family in soybeans and analyzed their phylogeny, gene duplication, structure, domains, conserved motifs, cis-elements in promoter regions for stress responses, and functional characteristics. We found that <i>GH3</i> genes are induced by pathogens in Group-II. Furthermore, eight out of 16 Group-II genes responded to cyst nematode infection. Overexpression of eight <i>GmGH3</i> genes can enhance soybean resistance to the cyst nematode. In addition, our metabolomic analysis showed that overexpression of them affected the content of salicylic acid, jasmonic acid, indole-3-acetic acid, and gibberellic acid. Overexpression of <i>GmGH3</i> in soybean affects the expression of genes involved in plant hormone biosynthesis. This provides valuable insights into the complex molecular mechanisms underlying the interaction between soybeans and cyst nematodes.