Functional Characterization Of VdSte7 In The Smoke Tree Wilt Fungus Verticillium Clahliae

In recent years,a large-scale outbreak of Cotinus coggygria in Beijing and other places caused serious economic losses in Fragrant Hill and other important landscape areas.The pathogen is Verticillium dahliae Kleb.It has a wide range of hosts and can infect more than 200 plants.The pathogen also forms a dormant structure,microsclerotia,which is a key link in the cycle of Verticillium disease and a difficult point in disease control.Studies have shown that the MAPK signaling pathway regulates the microsclerotia formation process.In recent years,the nutrient metabolism of fungi has been widely concerned,mainly divided into carbon source metabolism and nitrogen source metabolism,in which nitrogen source metabolism can directly affect fungal growth and development,sporulation ability,and thus affect pathogenicity.Studies have shown that the Fus3/Kssl MAPK signaling pathway can participate in the regulation of mycelial growth,attachment cell formation and nutrient metabolism,and is associated with pathogenicity.In order to clarify the function of the signaling pathway-related genes of V.dahlia,functional genomics and reverse genetics were used to investigate the role of microsclerotia formation,pathogenicity and nutrient metabolism,and to reveal related molecular regulation.The mechanism provides a theoretical basis for finding specific molecular targets,inventing new fungicides,and proposing effective prevention strategies.This study focused on the functional analysis of the Ste7 of the Fus3/Kssl MAPK signaling pathway,including the growth and development of microsclerotia,pathogenicity and nutrient metabolism.The main results are as follows:1.V.dahliae VdSte7 regulates the growth and development of microsclerotia:Knock of VdSte7 in the Fus3/Kssl signaling pathway of V.dahliae showed that there was no significant change in the number of microsclerotia formation,but the growth and development process was affected,it was difficult to form mature microsclerotia,inhibit melanin accumulation;gene deletion mutant The expression level of melanin synthesis-related genes decreased,and melanin synthesis and accumulation were inhibited.2.V.dahliae VdSte7 regulates the pathogenic process:Knockout of VdSte7 in the Fus3/Kssl signaling pathway of V dahliae,could not form attachment branches and invasive nails,could not penetrate the onion epidermis and celluloid membrane,and lost penetrating ability and pathogenicity to the host.3.VdSte11 is similar to VdSte7 and mainly participates in the function of Fus3/Kssl signaling pathway:Among the V.dahliae,VdSte11 is involved in the formation of a Ste11-Pbs2-Hogl signaling pathway in the Hog1 signaling pathway,and the other is the Ssk2-Pbs2-Hog1 signaling pathway.Single gene knockouts were performed on VdSte7 and VdStell,and the mutant phenotypes were highly similar.VdSte11 is not sensitive to high osmotic stress and cell wall inhibitor stress,and the aerial hyphae are reduced.Microsclerotia maturation and melanin accumulation are inhibited,and the infective structure and loss of pathogenicity cannot be formed.These phenotypes and other groups of Hogl signaling pathways There are significant differences,similar to the Ste7.It is concluded that V dahliae VdStell is mainly involved in the transmission of Ste 11-Ste7-Kss1/Fus3 signaling pathway and not involved in the regulation of Hog1 signaling pathway.4.V.dahliae VdSte7 and VdSte11 are involved in the regulation of nutrient metabolism:Knockout of VdSte7 and VdStell in the Fus3/Kssl signaling pathway of V.dahliae,the mutants were unable to utilize nitrate and nitrite,inhibiting the normal expression of nitrate and nitrite reductase-related genes,affecting both absorption and transport of non-dominant nitrogen sources.In the nitrogen source metabolic pathway,VdSte7 exerts a more direct regulatory capacity than VdSte11.