Abstract
BackgroundVerticillium wilt, caused by the soil-borne fungus of Verticillium dahliae Kleb., is one of the most devastating diseases of cotton. The complex mechanism underlying cotton resistance to Verticillium wilt remains uncharacterized. Identifying an endogenous resistance gene may be helpful to control this disease. Previous studies revealed that succinate dehydrogenase (SDH) is involved in reactive oxygen species (ROS)-induced stress signaling pathway that is likely to be triggered by salicylic acid (SA). Here, through the metabolomics and differential expression analyses in wilt-inoculated cotton (Gossypium hirsutum), we noticed that GhSDH1–1 gene in cotton may play an important role in the resistance to V. dahlia. Then we reported GhSDH1–1 gene and its functional analysis in relation to the resistance of cotton to V. dahliae.ResultsThe GhSDH1–1 gene in cotton root was significantly up-regulated after V. dahlia inoculation, and its expression level peaked at 12 and 24 h post-infection. SA can also induce the up-regulation of GhSDH1–1. Additionally, the functional analysis showed that GhSDH1–1-silenced cotton was more susceptible to V. dahliae than the control because of the significant decrease in abundance of immune-related molecules and severe damage to the SA-signaling pathway. In Arabidopsis thaliana, high expression of GhSDH1–1 conferred high resistance to V. dahliae. Arabidopsis that overexpressed GhSDH1–1 had higher resistance to V. dahliae infection compared with the wild-type.ConclusionsOur findings provide new insights into the role of GhSDH1–1; it positively regulates cotton resistance to Verticillium wilt. The regulatory mechanism of GhSDH1–1 is closely related to SA-related signaling pathway.
Highlights
Verticillium wilt, caused by the soil-borne fungus of Verticillium dahliae Kleb., is one of the most devastating diseases of cotton
Analysis of GhSDH1–1 structure and expression patterns in cotton treated with V. dahliae or salicylic acid Based on the results of an unpublished metabolomics analysis of disease responses in cotton, the metabolite succinic acid content decreased and the fumaric acid content increased after inoculation (Additional file 1: Figure S1)
To further investigate the function of these genes, real-time quantitative polymerase chain reaction (RT-qPCR) analysis was performed to detect the expression of the succinate dehydrogenase (SDH) gene in roots of inoculated cotton (Fig. 1)
Summary
Verticillium wilt, caused by the soil-borne fungus of Verticillium dahliae Kleb., is one of the most devastating diseases of cotton. Verticillium dahliae has a wide range of hosts, and in its dormant form, micro-sclerotium, is strongly resistant to environmental stresses. It inhabits the soil all the year round and can invade and occur in various growth stages of cotton, and it is difficult to control (Shaban et al 2018). The prevention and control of Verticillium wilt of cotton faces severe challenges caused by difficulties in implementing crop rotation, which leads to continuouscropping of cotton in fields and results in high numbers of the pathogen in soils, as well as the lack of resistant cotton varieties and effective fungicides (Cai et al 2009; Malik et al 2014). Recent studies have identified some key genes for resistance of cotton Verticillium wilt, such as GbVIP1 gene and GbTRP1 gene, which can regulate cotton resistance through positive and negative regulation, respectively (Zhang et al 2019; Miao et al 2019)
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