Study On Effector VPS26 And VPS29 Of Rab7 In Fusarium Graminearum

Fusarium graminearum is the main pathogenic fungus that causes wheat scab,which pollutes grains and produces DON toxin,and can seriously damage the health of people and livestock.DON toxin synthesis is not only affected by the physical and chemical influence factors,more mainly by the regulation of intracellular biological macromolecules.Rab7 can regulate the biosynthesis of DON,and Rab7 needs to combine with its effector to functionating.This paper studied the presumptive Rab7 effectors VPS26 and VPS29 and analyzed how they regulatate the DON toxin in F.graminearum.The interaction between Rab7 with VPS26 and Rab7 with VPS29 was studied.This study provide new drug targeting sites and theoretical basis to the prevention and treatment of Wheat gibberellic disease.The results showed that the accumulation of extracellular DON toxins in Rab7 mutant was significantly lower than that in wild type in the three different culture,and we almost can’t detect DON intracellular,indicating that FgRab7 in F.graminearum have a regulatory role on DON toxins production.In order to clarify the molecular mechanism of FgRab7 regulating DON toxin,the interaction between VPS26 with Rab7 and VPS29 with Rab7 was analyzed by yeast two-hybrid technique.The expression of VPS26 and VPS29 in wild type and Rab7 mutant were analyzed by fluorescence quantitative PCR.The results showed that VPS26 could interact with Rab7 in the activated state,while VPS29 did not have a direct interaction with Rab7,indicating that VPS26 was an effector of FgRab7,and VPS29 needed further study.At different times,the expression of VPS26 and VPS29 in wild type increased gradually.At the same time,the expression of VPS26 in FgRab7 deletion mutant was lower than that in wild type.The expression level of VPS26 increased gradually in the first 14 days,then decreased gradually,and the expression level of VPS26 was lower 8 times when 35 d.The expression of VPS29 present first rising then down and again rising.the expression level of VPS26 was lower than the wild type 2 times when 35 d.It indicated that Rab7 had a direct interaction with VPS26 and indirectly affected the expression of VPS29.Further analysis of VPS26 showed that FgVps26 knockout mutant present mycelial growth slowed down,colony morphological changes,decreased aerial mycelium,reduced sporulation,spore deformity and DON toxin production significantly decreased compared with wild type.This phenotypic defects can be restored in VPS26 complement mutant,indicating that VPS26 play an important physiological role in F.graminearum growth and toxins production.The expression of Rab7 and VPS29 in the VPS26 deletion mutant was analyzed by real-time fluorescence,the results showed that the expression of Rab7 and VPS29 in the wild type and mutant increased gradually at different cultivate stages.The expression of Rab7 and VPS29 decreased significantly in the same period,suggesting that VPS26 not only interacted with Rab7,but also restricted the expression of VPS29.The ability of FgVps26 knockout mutant to produce DON toxin was significantly lower than that of wild type.The amount of DON accumulated in wild type in each test period was 2 ~3 times higher than that in the mutant strain,indicating that the lack of Vps26 affect the synthesis of DON.In this paper,it is proved that VPS26 is an effector of Rab7 in F.graminearum,FgRab7 regulates the biosynthesis of DON toxin by interaction with VPS26.FgRab7 and FgVps26 have synergistic effect on DON toxin production.The results has a certain significance on revealing Rab7 Regulate DON synthetic molecular mechanism.