Study On The Regulation Of Typical Green Elicitors On The Redox Status And Disease Resistance In Postharvest Grape Berries

Grape berry is a highly nutritional fruit with bright color and soft as well as juicy.However,it is easily infected by pathogenic fungi because of the high water content,and the grey mold decay caused by Botrytis cinerea is the major fungal disease in postharvest grape berries.The study was designed to investigate the effect of different BABA concentrations treatment on the disease resistance in grape berries（Vitis vinifera L.×V.labrusca L.‘Kyoho’）and the possible mechanisms involved from the perspective of the redox status change.Moreover,in order to further verify the correlation between the priming response induced by BABA and the redox status,it is also studied that the effect of6-AN treatment on the reduction potential in grape fruit.The results were as follows:（1）Treatment with 100 or 500 mmol/L induced an obvious H₂O₂ burst at the storage of first day both in mock-inoculated and inoculated grape berries,increased the activities of chitinase andβ-1,3-glucanase and the expression of PR genes,such as VvNPR1.1、VvChi4 and VvPR2,as well as the accumulation of resveratrol and resveratrol dehydrodimer.Instead,1 mmol/L BABA treatment showed no disease resistance against fungal infection,whereas BABA at 10 mmol/L significantly activated the increase in the content of ROS and resistance-related substance and the expression levels of PRs when the fruits were inocubated with B.cinerea.It is implied that 10 mmol/L BABA can’t directly induce ROS burst,PR gene expression and phytoalexin synthesis,however,these defensive reactions were activated rapidly once the fruit subjected to pathogen infection.This indicated that BABA at high concentrations（100-500 mmol/L）induce the direct disease resistance,while the low concentrations accelerate the priming response.（2）BABA at 10 mmol/L could promote the accumulation of SA and NO,increased the activities of G6PDH、6PGDH、GR、DHAR and MDHAR,which were the key enzymes in the pentose phosphate pathway and GSH-AsA cycle.Besides,it also stimulated the synthesis of NADPH and GSH,improved the redox status of grape berries and significantly induced the primer resistance.Moreover,6-AN treatment will inhibit the physiological metabolic activities in grape fruit such as pentose phosphate pathway and GSH-AsA cycle,reduce NADPH and GSH content and the fruit reduction potential,thus suppressing the defense effect of BABA against B.cinerea infention.Therefore,the high redox status is a sufficient condition,which will induce the priming resistance in BABA-treated fruits.（3）It is confirmed that 10 mmol/L BABA treatment effectively triggered the activities of WRKYs transcription factors in the transcriptome sequencing experiment,and then induced the expression of PR genes,at the same time,it significantly promoted the synthesis of phytoalexin through the control of phenylpropnaoid pathway,thus the disease resistance of postharvest grape berries could be improved dramatically.