Evaluation Of Sensitivity Of Coniothyrium Minitans To Two Herbicides And Function Of Glutamine Synthetase

Coniothyrium minitans is a parasitic fungus of sclerotia,and has been developed as biological agent to control diseases caused by Sclerotinia sclerotiorum.The campatibility of the agent to the nonselective herbicide glyphosate and glufosinate is a key point to apply it to the soil before seeding.In this study,the sensitivity of strain ZS-1 of C.minitans to glyphosate and glufosinate was evaluated.The results were as follows:Both glyphosate and glufosinate had inhibitory effects on the mycelial growth of strain ZS-1,with EC₅₀0 714.3?g/mL and 574.5?g/mL,respectively.The inhibition to spore germination of glyphosate was much weaker(EC₅₀0 1019.8?g/mL),while glufosinate had no effect to spore germination of strain ZS-1.The two herbicides could inhibit strongly the mycelial growth of S.sclerotiorum strain 1980,with stronger inhibition of glufosinate(EC₅₀0 223.5?g/mL)than glyphosate(EC₅₀0 1695.8?g/mL).In the presence of both herbicides,parasitism of strain ZS-1 to sclerotia was reduced.Considered the characteristics of glyphosate and glufosinate,C.minitans could be used to the soil before seeding with the herbicides.Strain ZS-1 grows abnormally on PDA plates containing glufosinate.It was suspected that the target gene of glufosinate plays an important role in the growth and sporulation of C.minitans.Three genes containing the conserved domain of glutamine synthetase were found,one of which was FluG,and the other two were glutamine synthetase-like proteins,which are named GlnA1?CmZS1₀2675?and GlnA2?CmZS1₀7614?,respectively.In order to clarify the function of GlnA1 and GlnA2,they were knocked out by the split marker method.However knockout of GlnA1 was lethal to the strain ZS-1.When adding a certain amount of the glutamine,mutains can restore growth and produce spores.The mutains lost senditivity to glufosinate.There was no significant difference between GlnA2 knockout transformants and the strain ZS-1 in colony morphology,mycelial morphology,growth,conidial production,biomass,and the sensitivity to ammonium phosphine.The results demonstrated that GlnA1,but not GlnA2 was the target of glufosinate.