Genome-wide identification of the GST gene family and its expression pattern analysis under cold stress in quinoa (Chenopodium quinoa Willd.)

Background: Glutathione S-transferase (GST) is an antioxidant enzyme essential for cell protection because of its scavenging of reactive oxygen species accumulated under various stresses. Cold stress studies on the GST gene family have been conducted in several dicotyledonous and monocotyledonous plants, including Arabidopsis , rice, sweet potato, cantaloupe, and pumpkin. However, no relevant studies have been conducted on quinoa to date. Results In the present study, 59 GST (CqGST) genes were identified in the C. quinoa genome, among which 34 were located in the cytoplasm, 20 in the chloroplasts, and five in the ribosomes. Our phylogenetic analysis of CqGST and GST genes from Arabidopsis and rice showed that these genes were clustered into eight subfamilies, namely Tau, Phi, GHR, Zeta, Lambda, EF1B, DHER, and TCHQD. A total of 59 CqGSTs were located on 14 chromosomes, and none were located on chromosomes 00, 4, 9, 13, and 15. Eleven pairs of tandem-duplicated genes and 12 pairs of segmentally duplicated genes were identified in the CqGST gene family. The promoter region of each CqGST contained at least one cis-element associated with adversity. We selected 16 representative genes for fluorescence quantitative RT-PCR to verify gene expression and found that most of the CqGST genes were highly expressed in the roots and recovered for 3 h after different cold treatment times, indicating that the GST family plays an important role in quinoa cold stress. Conclusions In the present study, 59 GST genes were identified in quinoa, and gene duplication events were found to be the main drivers of GST gene family evolution in this species. Our results provide a basis for further studies on the function of GST genes in quinoa as well as a research basis for breeding quinoa in high-altitude cold regions, indicating the candidate genes for enhancing quinoa yield.