Genome-wide analysis of the GST gene family in Gossypium hirsutum L.

Glutathione-S-transferase (GST) is a ubiquitous multi-functional protein superfamily that plays important roles in plant primary and secondary metabolism, stress and intercellular signal transduction. Concomitantly, it also functions as a ligand in the metabolism of plant hormones and substance transport. In order to understand the GST gene family in upland cotton (Gossypium hirsutum L.), herein we analyzed the species, evolutionary relationship, physical location, gene structure, conserved motifs and expression patterns. We identified 70 GST genes in the whole genome of upland cotton, and divided them into U, F, T, Z, EF1Bγ and TCHQD groups by phylogenetic tree and gene structure analyses. The gene mapping analysis indicated that the GST genes were on every chromosome except chromosome AD/At2, AD/At4, AD/At5, AD/Dt5 and AD/Dt10. Moreover, the GST gene cluster appeared on four chromosomes (AD/At9, AD/Dt7, AD/Dt12 and AD/Dt13). qRT-PCR assays showed that eight genes (GhGSTF2-9) were expressed in the root, stem, leave and fiber of different developmental stages while GhGSTF1 might be a pseudogene. Combining qRT-PCR and bioinformatic analysis, we speculated that GhGSTF8 might be involved in the transport and accumulation of proanthocyanidins/anthocyanins; GhGSTF4, 6 and 9 might play roles in regulating the growth and stress response of upland cotton; the function of GhGSTF2, 3, 5 and 7 remains to be further investigated. Our work provides a theoretical basis for further studies on the molecular evolution and function of the GST gene family in upland cotton.