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.