Influence Of Knockout Of PKS Gene In Trichoderma Sp.3838 On Eggs Hatching And RNAi Of Egg Hatching Genes Of Meloidogyne Incognita

Trichoderma sp.3838 could promote egg hatching of Meloidogyne incognita and two active compounds 282 and 298 were isolated from this strain before this study.This study will further sutdy the corresponding relationship on egg hatching and active compounds and the related genes of egg hatching in M.incognita.Besides gene PKS2.4,5 positive knockout strains were obtained by knocking out 6type I PKS genes(PKS2.4,PKS22.1,PKS32.1,PKS32.3,PKS57.2,PKS101.3)of the strain3838.The LC-MS of ethyl acetate extract of strains fermentation showed that only the knockout strain ?PKS32.1 losed ability of generating active compounds.The hatching effect of strain ?PKS32.1 was reduced by over three times.Knockout strain ?PKS32.1 had weak nematicidal activity against nematodes.The life span of hatched nematodes of strain?PKS32.1 was not significant differences to the wild-type strain and contrast.The infection ability to tomato root of hatched nematodes of strain ?PKS32.1 was reduced.Strain?PKS32.1 showed capacity to infect the egg.The infection rate of this strain had not significant differences to the wild-type strain.Strain ?PKS32.1 could only infect dead J2 s,and couldn?t infect egg shells and active J2 in the whole process of infection test.Other 4 knockout strains ?PKS22.1,?PKS32.3,?PKS57.2,?PKS101.3 still produce active compounds,which lead to unchanged hatching effect with wild-type strain and weak nematicidal activity.The nematodes life span of 4 knockout strains was not significant differences to the wild-type strain and control group.The infection ratios to tomato root of4 knockout strains than the wild-type strain and contrast was also reduced.The 4 knockout strains showed the same result with wild type strain in the experiment of infection ability on the egg,egg shell and J2 of M.incognita.The results of RNAi experiment on the hatching-related genes mpk-2 and let-60 of M.incognita showed that the relative expression of mpk-2 and let-60 genes was decreased,the hatching efficiency of egg masses was also significantly reduced,and the mortality rate of hatched nematodes was significantly increased.The strain knockouting PKS32.1 lose ability of producing hatching substance,and then decreased the ability to stimulate eggs hatching effect on M.incognita.This result confirmed that strain 3838 promoted egg hatching of M.incognita by generating active PKS compounds.At the same time,two gene mpk-2 and let-60 of M.incognita were identified to relating to egg hatching of M.incognita.