Verticillium wilt, a devastating disease in cotton caused by Verticillium dahliae, reduces cotton quality and yield. Heterotrimeric GTP-binding proteins, consisting of Ga, Gb, and Gc subunits, transducers of receptor ...Verticillium wilt, a devastating disease in cotton caused by Verticillium dahliae, reduces cotton quality and yield. Heterotrimeric GTP-binding proteins, consisting of Ga, Gb, and Gc subunits, transducers of receptor signaling, function in a wide range of biological events. However, the function of Ga proteins in the regulation of defense responses in plants is largely unexplored, except for a few reports on model species. In the present study, a cotton G-protein a-subunit-encoding gene(GhGPA) was isolated from Verticillium wilt-resistant Gossypium hirsutum(upland cotton) cv. ND601. GhGPA transcription was up-regulated under V. dahliae stress, with higher expression in tolerant than in susceptible cotton cultivars.Subcellular localization revealed GhGPA to be located in the plasma membrane. GhGPA shows high(85.0%) identity with Arabidopsis AT2 G26300(AtGPA1), and AtGPA1 gpa1-4 mutants displayed susceptibility to V. dahliae. Ectopic expression of GhGPA successfully restored the resistance of Arabidopsis gpa1-4 mutants to Verticillium wilt and made them more resistant than the wild type. Overexpression of GhGPA in Arabidopsis markedly increased the resistance and resulted in dramatic up-regulation of pathogenesis-related(PR) genes and increased in H2 O2 accumulation and salicylic acid(SA) and jasmonic acid(JA) contents. However, suppressing GhGPA expression via virus-induced gene silencing(VIGS)increased susceptibility to Verticillium wilt, down-regulated the expression of PR and marker genes in SA and JA signaling pathways, and reduced H2 O2 content. The contents of SA and JA in Arabidopsis gpa1-4 and VIGS cotton were lower than those in the wild type and empty-vector control. However,GhGPA-overexpressing Arabidopsis contained more SA and JA than the wild type when inoculated with V. dahliae. Thus, GhGPA plays a vital role in Verticillium wilt resistance by inducing SA and JA signaling pathways and regulating the production of reactive oxygen species. These findings not only broaden our knowledge about the biological role of GhGPA, but also shed light on the defense mechanisms involving GhGPA against V. dahliae in cotton.展开更多
基金supported by the National Key Research and Development Program of China(2016YFD0101006)the China Agricultural Research System(CARS15-03)the Outstanding Youth Found of Hebei Province(C2019204365)。
文摘Verticillium wilt, a devastating disease in cotton caused by Verticillium dahliae, reduces cotton quality and yield. Heterotrimeric GTP-binding proteins, consisting of Ga, Gb, and Gc subunits, transducers of receptor signaling, function in a wide range of biological events. However, the function of Ga proteins in the regulation of defense responses in plants is largely unexplored, except for a few reports on model species. In the present study, a cotton G-protein a-subunit-encoding gene(GhGPA) was isolated from Verticillium wilt-resistant Gossypium hirsutum(upland cotton) cv. ND601. GhGPA transcription was up-regulated under V. dahliae stress, with higher expression in tolerant than in susceptible cotton cultivars.Subcellular localization revealed GhGPA to be located in the plasma membrane. GhGPA shows high(85.0%) identity with Arabidopsis AT2 G26300(AtGPA1), and AtGPA1 gpa1-4 mutants displayed susceptibility to V. dahliae. Ectopic expression of GhGPA successfully restored the resistance of Arabidopsis gpa1-4 mutants to Verticillium wilt and made them more resistant than the wild type. Overexpression of GhGPA in Arabidopsis markedly increased the resistance and resulted in dramatic up-regulation of pathogenesis-related(PR) genes and increased in H2 O2 accumulation and salicylic acid(SA) and jasmonic acid(JA) contents. However, suppressing GhGPA expression via virus-induced gene silencing(VIGS)increased susceptibility to Verticillium wilt, down-regulated the expression of PR and marker genes in SA and JA signaling pathways, and reduced H2 O2 content. The contents of SA and JA in Arabidopsis gpa1-4 and VIGS cotton were lower than those in the wild type and empty-vector control. However,GhGPA-overexpressing Arabidopsis contained more SA and JA than the wild type when inoculated with V. dahliae. Thus, GhGPA plays a vital role in Verticillium wilt resistance by inducing SA and JA signaling pathways and regulating the production of reactive oxygen species. These findings not only broaden our knowledge about the biological role of GhGPA, but also shed light on the defense mechanisms involving GhGPA against V. dahliae in cotton.
