Functional Analysis Of Pathogenic Related Gene Vdsho1 In Verticillium Dahliae

Verticillium dahliae is a typical soil-borne plant pathogen responsible for vascular wilt diseases that damage the normal development in some important crops.Cotton,a large acreage economically important crop,has been under the threat of V.dahliae worldwide.V.dahliae can survive in soil in the form of microsclerotia for many years.Because V.dahliae causes disease on many crops,it has been a huge challenge for disease control worldwide.Control strategies like biological control and improved genetic resistance were not effective.Clarifying the key genes responsible for virulence in Verticillium species may be conducive to improvement of crop breeding and effective deployment of new disease control strategies based on the molecular level.Previous studies indicate that during the process of plant pathogens infection,the pathogen mitogen-activated protein kinase(MAPK)cascade is required to adapt to extracellular stimuli such as osmotic,oxidative and other stresses.Furthermore,MAPK plays role in fungal hyphae growth,the formation of the specialized appressorium structure and secretory process of cell well degrading enzymes.Tetraspan transmembrane protein Sho,a type of conserved protein in fungus,plays a role upstream of the MAPK signaling pathway.The V.dahliae strain Vd8,a defoliating strain,was used to generate the deletion mutant.We successfully constructed the pathogenic related gene VdShol knock-out vector,and obtained the gene delection mutant through ATMT(Agrobacterium tumefaciens-mediated transformation).VdSho1 function was analyzed preliminarily,and the main results are presented as follow:1.In this study,we used the homology cloning strategy to obtain the VdSho1.VdShol contains an open reading frame of 882bp with two introns,and encodes a predicted 293-amino-acid protein.Bioinformatics analysis of this amino acid sequence displayed VdShol includes four predicted transmembrane domains near the N-terminus(amino acids 23-45,52-74,79-101 and 114-136,respectively)and an SH3 domain at the C-terminus(amino acids 193-237).BLAST results showed VdSho1 exhibited 65%and 58%similaritied to MoShol and FoShol in M.oryzae and F.oxysporum,respectively.2.?Vdshol mutant displayed different growth and development-related traits compared to wild type strain Vd8.?Vdsho1 mutant showed abnormal colony expansion,conidia germination,conidia production and polar growth,and those results indicate that VdShol was necessary for fungal normal growth and development.Shol deletion mutants showed increased sensitivity to oxidants,indicate that VdSho1 protein participated in the oxidative stresses and protects cells from oxidative damage.3.Cotton inoculated with ?Vdsho1 mutant strain showed mild and later disease symptoms compared with the gene complement mutant and wild type strain,suggesting a role of VdShol on fungal pathogenicity.Further study found ?Vdsho1 attenuated the ability of adhesion on roots of Arabidopsis,reduced the accumulation in the in cotton stems,but showed almost no obvious change in disease penetration.