Genome-wide identification, expression and functional analysis of glutathione s-transferase family members in Quercus dentata under heavy metal stresses

Glutathione <i>S</i>-transferases (GSTs), a superfamily of multifunctional enzymes, are involved in plant growth, development, and response to biotic and abiotic stresses. In this study, 86 members of the GST family, denoted <i>QdGST</i>, were identified in the <i>Quercus dentata</i> genome and found to be distributed among six of the GST classes, with the majority in the tau class, followed by the lambda and phi classes. This uneven distribution of <i>QdGST</i> genes was observed across 11 chromosomes. Thirty-one tandem and seven segmental duplication events were found to have contributed to the expansion of the QdGST family. Moreover, a total of 29 categories of <i>cis</i>-acting elements were identified in the promoters of the <i>QdGST</i> genes, most of which were involved in defense and stress responses. RNA sequencing analysis revealed that most <i>QdGST</i> genes displayed tissue-specific expression patterns, and that cadmium or lead treatment induced the expression of 31 of them, most of which belonged to the tau class. Quantitative real-time PCR analysis confirmed the expression of cadmium- and lead-induced <i>QdGST</i> genes, with <i>QdGSTU20</i> and <i>QdGSTU36</i> in particular showing strong upregulation. <i>QdGSTU36</i> also enhanced yeast growth under cadmium and lead stresses when expressed in yeast. These findings lay a crucial foundation for further work to clarify the biological functions of <i>QdGST</i> genes associated with heavy metal tolerance in <i>Q. dentata</i>.