Genome-Wide Identification, Characterization, and Expression Profiling of Glutathione S-Transferase (GST) Family in Pumpkin Reveals Likely Role in Cold-Stress Tolerance

Plant growth and development can be adversely affected by cold stress, limiting productivity. The glutathione -transferase (GST) family comprises important detoxifying enzymes, which play major roles in biotic and abiotic stress responses by reducing the oxidative damage caused by reactive oxygen species. Pumpkins ( ) are widely grown, economically important, and nutritious; however, their yield can be severely affected by cold stress. The identification of putative candidate genes responsible for cold-stress tolerance, including the GST family genes, is therefore vital. For the first time, we identified 32 ( ) genes using a combination of bioinformatics approaches and characterized them by expression profiling. These genes represent seven of the 14 known classes of plant , with 18 s categorized into the tau class. The s were distributed across 13 of pumpkin's 20 chromosomes, with the highest numbers found on chromosomes 4 and 6. The large number of genes resulted from gene duplication; 11 and 5 pairs of genes were segmental- and tandem-duplicated, respectively. In addition, all genes showed organ-specific expression. The expression of the putative genes in pumpkin was examined under cold stress in two lines with contrasting cold tolerance: cold-tolerant CP-1 ( ) and cold-susceptible EP-1 ( ). Seven genes ( , , , , , , and ) were highly expressed in the cold-tolerant line and are putative candidates for use in breeding cold-tolerant crop varieties. These results increase our understanding of the cold-stress-related functions of the GST family, as well as potentially enhancing pumpkin breeding programs.