Study of glutathione S-transferase (CqGSTs) gene expression patterns, the response of basic helix–loop–helix (bHLH) transcription factor and genome-wide identification gene family in quinoa (Chenopodium quinoa Willd.) and its mechanisms of salt stress tolerance

Quinoa grains are nutritionally rich and balanced, rich in protein, starch, VB1, folic acid, minerals (Ca, Zn, Fe) and other nutrients and grow at high altitude (> 3500 m above sea level) all year round; it is subjected to drought, low temperature, salt and other abiotic stresses during its growth and development; basic helix–loop–helix (bHLH) family is the second largest gene family in plants and is involved in many biological processes such as plant growth, development, metabolism and resistance to abiotic stress. In bioinformatics and expression analysis of glutathione S-transferase (GST) gene in quinoa in this study, 114 CqGST genes were identified from the whole genome of quinoa by bioinformatics methods. The phylogenetic tree showed that 114 CqGST genes were divided into seven subgroups. Phylogenetic analysis of these genes suggested that tandem and fragment replication events played a key role in the expansion of the CqGSTs gene family, and the CqGST genes may have undergone strong purification selection during the evolution process. Analysis of salt-treated transcriptome from the roots of salt-tolerant and salt-sensitive quinoa cultivars showed that salt treatment induced changes in the expression levels of CqGSTs genes. By comparing the sequences of the bHLH gene family members of Arabidopsis thaliana and the bHLH transcription factor family members Quinoa most of the bHLH transcription factors of quinoa have high homology with that of Arabidopsis thaliana. The number of exons contained in CqGST gene ranged from 1 to 14, among which CqGSTL2 contained 14 exons, indicating that CqGSTL2 contained 14 exons, the gene with the highest number of exons, respectively. The number of exons in six CqGSTZ members was significantly different, including three members have two exons and three have nine exons. Studies on chromosome distribution are that except for no CqGST gene on chromosome 09, all the other chromosomes were identical; there was CqGST gene distribution, and chromosome 07 contains 20 CqGST genes, which was one of CqGST gene distribution. CqGSTL1 and CqGSTU1 cannot locate specific chromosomes due to the quality of the genome. In order to explore the expression pattern of GST gene, different tissues or RNA-seq data of Quinoa from various developmental stages of organs were systematically analyzed. In class U, CqGSTU22, CqGSTU67, CqGSTU43, CqGSTU42, CqGSTU15, in class L, CqGSTL1 and CqGSTL5, in class Z, CqGSTZ5, DHAR class CqDHAR2 and CqDHAR3 were strongly expressed in various varieties tissues and organs. The CqGST, U66, CqGSTF20 and CqGSTF23 were not expressed in the 11 tissues or organs tested. Related to the temporal and spatial expression patterns of these genes, there were multiple genes in each type in the seedlings medium and high expression such as CqGSTL4, CqGSTL6, respectively.