Zhu Longfu

Resistance of Cotton and Tomato to Verticillium dahliae from Cotton is Independent on Ve1

Verticillium wilt is one of the devastating diseases for cotton in China. Identification of disease-resistant genes and elucidation of the resistance mechanism are the basis for resistance breeding of cotton. In this study, Ve1 , the only cloned R gene to Verticillium wilt from tomato ( Solanum lycopersicum ), was overexpressed in Nicotiana benthamiana and cotton ( Gossypium hirsutum ), to evaluate its value in the control of Verticillium wilt in cotton. The results showed that overexpression of Ve1 in N. benthamiana could not improve resistance to more strains of V. dahliae from tomato and cotton. Meanwhile, the expression of disease resistant-related genes was not influenced by overexpression of Ve1 in N. benthamiana through RT-PCR, suggesting that the signal pathway required by Ve1 may not be complete in N. benthamiana . Furthermore, Ve1 -overexpressing cotton lines showed similar results to that in wild type plants after inoculated with defoliating pathotype Verticillium strain ‘V991’ from cotton and Verticillium strain ‘JR2’ from tomato. Nevertheless, tomato isogenic lines Craigella GCR218 and Craigella GCR26, which are resistant and susceptible to race1 Verticillium strains, showed high resistance to defoliating pathotype Verticillium strain ‘V991’, suggesting that the resistance of tomato to Verticillium strain ‘V991’ from cotton do not depend on Ve1 . The identification based on two markers showed that obvious difference exited between Verticillium strains from cottonand tomato. The Verticillium strains of ‘JR2’ and ‘M050414’, race1 and race 2 strains of tomato V. dahliae , were clustered to the non-defoliating group of V. dahliae . While, ave1 ,the avirulence gene specificly recognized by Ve1, was not found in any Verticillium strain from cotton employed in this study, which may explain why overexpression of Ve1 could not improve the cotton resistance to Verticillium strains from cotton. When we silenced the expression level of GbSERK1 by virus-induced gene silencing, the resistance of ‘Hai 7124’ to V. dahliae was significantly attenuated, which inferred the signal pathway required by Ve1 may also be responsible for the resistance of cotton to V. dahliae . In this study, the evolution of receptor-like protein in cotton and the signal pathway in cotton resistance to V. dahliae were also discussed.