Island Cotton <em>Gbve1</em> Gene Encoding A Receptor-Like Protein Confers Resistance to Both Defoliating and Non-Defoliating Isolates of <em>Verticillium dahliae</em>

<div><p>Verticillium wilt caused by soilborne fungus <em>Verticillium dahliae</em> could significantly reduce cotton yield. Here, we cloned a tomato <em>Ve</em> homologous gene, <em>Gbve1</em>, from an island cotton cultivar that is resistant to Verticillium wilt. We found that the <em>Gbve1</em> gene was induced by <em>V. dahliae</em> and by phytohormones salicylic acid, jasmonic acid, and ethylene, but not by abscisic acid. The induction of <em>Gbve1</em> in resistant cotton was quicker and stronger than in <em>Verticillium</em>-susceptible upland cotton following <em>V. dahliae</em> inoculation. <em>Gbve1</em> promoter-driving GUS activity was found exclusively in the vascular bundles of roots and stems of transgenic <em>Arabidopsis</em>. Virus-induced silencing of endogenous genes in resistant cotton via targeting a fragment of the <em>Gbve1</em> gene compromised cotton resistance to <em>V. dahliae</em>. Furthermore, we transformed the <em>Gbve1</em> gene into <em>Arabidopsis</em> and upland cotton through <em>Agrobacterium</em>-mediated transformation. Overexpression of the <em>Gbve1</em> gene endowed transgenic <em>Arabidopsis</em> and upland cotton with resistance to high aggressive defoliating and non-defoliating isolates of <em>V. dahliae</em>. And HR-mimic cell death was observed in the transgenic <em>Arabidopsis</em>. Our results demonstrate that the <em>Gbve1</em> gene is responsible for resistance to <em>V. dahliae</em> in island cotton and can be used for breeding cotton varieties that are resistant to Verticillium wilt.</p> </div

<i>Gbve1</i> confers Verticillium wilt resistance in transgenic upland cotton.

<p>(A). Relative expression level of <i>Gbve1</i> genes in T₁ transgenic cotton lines. (B). The disease indices of T1 transgenic cottons with infection by <i>V. dahliae</i> defoliating isolate V991 (upper panel) and non-defoliating isolate BP2 (down panel). Results were presented as means±SE from three replications with at least 10 plants per replication. (C). The phenotypes of transgenic cotton lines with infection by <i>V. dahliae</i> isolates.</p

<i>Gbve1</i> confers Verticillium wilt resistance in transgenic <i>Arabidopsis</i>.

<p>(A). The resistant levels of transgenic <i>Arabidopsis</i> (left panel) to <i>V. dahliae</i> was related to the expression levels of the <i>Gbve1</i> gene in the T₃ independent transgenic lines (right panel). The disease indices were presented means±SE from three replications with at least 16 plants per replication. (B). Phenotype comparison of transgenic line R5 and WT infected with <i>V. dahliae</i> isolates V991 and BP2. (C).The <i>Gbve1</i> transgenic <i>Arabidopsis</i> were resistance to <i>V. dahliae</i> through cell death response. Bar = 200 µm. (D). Expressional levels of genes relative to pathogen resistance in transgenic line R5.</p

GUS activities in transgenic <i>Arabidopsis</i> plants containing the PGbve1:GUS construct.

<p>(A). GUS activities in the <i>Arabidopsis</i> plantlet. (B). Magnified view of vascular bundles in roots and stems.</p