| Grapes are one of the most consumed fruits,rich in many nutrients,such as amino acids,sugars,organic acids,and vitamins,globally and are deeply loved by consumers.However,grapes are infected by Penicillium sp,Aspergillus sp,Rhizopus sp and other fungi during picking and transportation.These infections lead to fruit decay and loss of commercial value.Aspergillus tubingensis is one of the main pathogens of grape,which causes grape postharvest smut and produces ochratoxin A,which seriously endangers human health.Sporidiobolus pararoseus Y16 is an antagonistic yeast proven to control grape postharvest diseases,but its biocontrol efficacy needs to be further improved.In this study,S.pararoseus Y16 was induced by γ-aminobutyric acid(GABA),and its biocontrol efficacy on postharvest smut of grapes was investigated.Further,the possible mechanisms involved in improving biocontrol effectiveness were explored.The main research results are as follows:1.GABA-induced culture can significantly improve the control effect of S.pararoseus Y16 on grape postharvest smut.And the best concentration was 4 mg / mL.After 9 d of storage,GABA-induced S.pararoseus Y16 could significantly reduce the natural decay of grapes and had no significant adverse effect on grapes’ storage quality.2.The physiological mechanisms of GABA-induced to improve the control efficacy of S.pararoseus Y16 include:(1)GABA-induced S.pararoseus Y16 can significantly reduce the spore germination rate,germ tube length and colony diameter of A.tubingensis.(2)GABA-induced S.pararoseus Y16 could improve the growth ability of S.pararoseus Y16 in grape wounds and surfaces.(3)GABA-induced S.pararoseus Y16 can enhance the disease-resistant enzyme activities of grape,increase the content of total phenols and flavonoids,improve the ability of grape enzymatic peroxidation defense system,and reduce cell membrane peroxidation.(4)GABA-induced S.pararoseus Y16 could increase the activities of catalase and chitinase,reduce the accumulation of Malondialdehyde,and improve the antioxidant stress and antifungal ability of S.pararoseus Y16.3.Proteomics study of GABA-induced S.pararoseus Y16 showed that:(1)The expression of GABA shunt pathway-related proteins was up-regulated,and the expression of GABA synthesis protein was down-regulated,which promoted the degradation of GABA into acetyl-co A and amino acids for the growth and metabolism of S.pararoseus Y16.(2)The ability of S.pararoseus Y16 to grow and reproduce was improved by up-regulating the expression of proteins such as deoxyribose synthesis,acetyl-co A synthesis,cell cycle and translation.(3)The expression of proteins related to terpenoids,sterols and glucan was up-regulated,which enhanced the synthesis ability and antibacterial ability of cell membrane and cell wall,and improved the ability of S.pararoseus Y16 to resist stress.(4)The up-regulated expression of proteins associated with amino acid synthesis such as valine,leucine and isoleucine promoted the protein synthesis and growth metabolism of S.pararoseus Y16.4.Transcriptome analysis of GABA-induced S.pararoseus Y16 showed that:(1)The upregulation of genes related to gluconeogenesis pathway,mitosis,acetyl-co A synthesis,TCA cycle and electron transport chain promoted the glucose and energy production in S.pararoseus Y16,which enhanced the growth and proliferation ability of S.pararoseus Y16.(2)The up-regulated expression of genes related to ion transport,cell wall remodeling and antioxidant synthesis improved the ability of S.pararoseus Y16 to resist stress.(3)The up-regulated expression of key genes in shikimic acid pathway and aspartate pathway promoted the synthesis of amino acids in S.pararoseus Y16.The production of these amino acids and various secondary metabolites were closely related to the growth and resistance of S.pararoseus Y16. |
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