Study On The Virulence Function Of The Vesicle Fusion Proteins VdSec22 And VdSso1 Of Verticillium Dahliae Mediated Extracellular Protein Secretion

Extracellular proteins play an important role in host infection.The secretory processes of extracellular proteins are usually controlled by the secretory system of vesicular transport.In this study,comparative analysis of vesicular fusion proteins and identification of virulence function were carried out by using the Vd991 genome of isolated from cotton.Comparative genomics analysis showed that the vesicular fusion protein encoded by Vd991 was composed of 22 SNARE(Soluble N-ethylmaleimide-sensitive Factor Attachment Protein Receptor)proteins,4 SM(Sec1 / Munc18)family proteins and 10 Rab GTPase.Of these 22 SNARE proteins are divided into 5subfamilies:Qa,Qb,Qc,Qbc and R proteins;Various proteins forvesicular fusion complex in different combinations of [Qa-Qb-Qc-Qbc-R]-SM-Rab,which participate in the transport process of endoplasmic reticulum-Golgi body-secretory vesicle-plasma membrane fusion.Further studies on the virulence function of the key components of the vesicular fusion protein complex of Verticillium dahliae were carried out.VdSec22(R)and VdSso1(Qa)are important components of "endoplasmic reticulum-Golgi body" and "secretory vesicle-plasma membrane fusion" vesicular fusion complex,The pathogenicity and cell reproduction of ?VdSec22 and ?VdSso1 knockout to susceptible cotton Junmian 1 were significantly lower than those of wild type.Two corresponding deletion mutants(?VdSec22 and ?VdSso1)were restored to their pathogenicity and cell reproduction.The results showed that "endoplasmic reticulum-Golgi body" vesicle fusion complex component VdSec22 and "secretory vesicle-plasma membrane fusion" vesicular fusion complex component VdSso1 were necessary for pathogenicity of Verticillium dahliae.The analysis of the wilting activity of the extracellular protein showed that the wild strain Vd991 could cause the typical wilting symptoms of cotton(Junmian1)after 72 hours of treatment with the extracellular protein.However,the activity of extracellular secretory proteins of?VdSec22 and ?VdSso1 decreased significantly in the same amount of mutants.It is shown that the membrane vesicle fusion complex component VdSec22 and VdSso1 mediate the secretion of extracellular proteins.iTRAQ(identification of isotope relative markers and relative quantitative techniques)showed that Vdsec22 and Vdsso1 control 115 and 72 proteins,whichcovered 42.4% and 26.7% of the identified withering active components,respectively.Functional cluster analysis showed that the proteins regulated by Vdsec22 and Vdsso1 were mainly involved in the degradation of cell wall components such as pectin,cellulose and xylan.These results suggest that vesicular fusion protein is a key component in extracellular transport of Verticillium dahliae.This provides a theoretical basis for the systematic study of vesicular fusion protein involved in pathogenicity and the development of key targets for the prevention and control of Verticillium wilt.