J Xu, X Wang, Y Li, J Zeng, G Wang, C Deng, W Guo

Plant Biotechnology Journal: 5 March 2018, DOI: 10.1111/pbi.12900

Summary

Verticillium wilt (VW), caused by soil-borne fungi of the genus Verticillium, is a serious disease affecting a wide range of plants and leading to a constant and major challenge to agriculture worldwide. Cotton (Gossypium hirsutum) is the world's most important natural textile fibre and oil crop. VW of cotton is a highly devastating vascular disease; however, few resistant germplasms have been reported in cotton. An increasing number of studies have shown that RNA interference (RNAi)-based host-induced gene silencing (HIGS) is an effective strategy for improving plant resistance to pathogens by silencing genes essential for the pathogenicity of these pathogens. Here, we have identified and characterized multifunctional regulators of G protein signalling (RGS) in the Verticillium dahliae virulence strain, Vd8. Of eight VdRGS genes, VdRGS1 showed the most significant increase in expression in V. dahliae after treating with the roots of cotton seedlings. Based on the phenotype detection of VdRGS1 deletion and complementation mutants, we found that VdRGS1 played crucial roles in spore production, hyphal development, microsclerotia formation and pathogenicity. Tobacco rattle virus-mediated HIGS in cotton plants silenced VdRGS1 transcripts in invaded V. dahliae strains and enhanced broad-spectrum resistance to cotton VW. Our data demonstrate that VdRGS1 is a conserved and essential gene for V. dahliae virulence. HIGS of VdRGS1 provides effective control against V. dahliae infection and could obtain the durable disease resistance in cotton and in other VW-susceptible host crops by developing the stable transformants.

See: http://onlinelibrary.wiley.com/doi/10.1111/pbi.12900/full

Figure 1: Identification and expression of RGS genes in Verticillium dahlia. (a) Phylogenetic relationship of the eight RGS genes in V. dahliae. (b) Prediction of the domains of the eight RGS proteins. The eight RGS proteins not only have the RGS domain but also contain other functional domains. (c) Expression of eight RGS genes in V. dahliae induced by the roots of cotton seedlings at different time points. The roots of 2-week-old cotton seedlings are used to induce the V. dahliae. Verticillium dahliae spore suspensions induced for 0, 2, 4, 6, 12 and 24 hours (h) were collected separately and used for RNA isolation. RGS gene expressions were examined by qRT–PCR. The data represent the mean ± SD of three samples from three independent tests at each time point. ‘*’: significant difference at P < 0.05; ‘**’: significant difference at P < 0.01.