Evolutionary, transcriptomic and functional analyses revealed a GST cluster played an important role in Verticillium wilt resistance in Gossypium hirsutum

Cotton (Gossypium hirsutum) is an important cash crop that can produce the fiber and oilseed. It often undergoes various biotic or abiotic stresses in growth periods. Verticillium wilt, caused by Verticillium dahliae, is a severe disease in cotton. The molecular mechanism of cotton resistance to Verticillium wilt needs to be further investigated. In the present study, we firstly revealed a tau Glutathione S-transferases (GSTs, E.C.2.5.1.18) cluster (including Gh_A09G1508, Gh_A09G1509 and Gh_A09G1510) participating in the Verticillium wilt resistance in cotton based on evolutionary, transcriptomic and functional analyses. This gene cluster located in chromosome 09 of A –subgenome. Evolutionary analysis showed that the cluster originated from the unbalancing gene losses in genetic innovation during the formation of allotetraploid (G. hirsutum). Transcriptome analysis revealed that the cluster took part in Verticillium wilt resistance. Based on the GhGST gene Gh_A09G1509 which was highest differentially expressed in the resistant cultivar under V. dahliae stress, we overexpressed the gene of the cluster in tobacco, and it can greatly enhance Verticillium wilt resistance. When the genes of the cluster suppressed via virus-induced gene silencing (VIGS), the plants of resistant cultivar Nongda601 showed significantly susceptible to the disease. These results demonstrated that the GST cluster played an important role in Verticillium wilt resistance in G. hirsutum. Further investigation of the molecular mechanism showed that the cluster regulated the delicate equilibrium between production and scavenging of H2O2 during V. dahliae stress.