Validation Of Differentially Expressed Genes In Postharvest Longan Fruit During Quality Deterioration

Longan is one of special fruits in South China.,rapidly deteriorates after harvest.Pericarp browning and aril breakdown are the most important storage characteristics of longan fruit,which influence the storage and distribution of longan.There are many differentially expressed genes relative to longan pericarp browning and aril breakdown during storage.There are different between those differentially expressed genes in longan fruit whichstoraged in room temperature and low temperature.there are different between those differentially expressed genes in different varieties of longan fruit.Therefore,screen and verify the main differentially expressed genes in longan fruit during storage is of important theoretical and practical significances.‘Shixia’‘Chuliang’‘Shuiyan’and ‘Dongbi’ longan fruit were used to compare the difference of longanpericarp browning and aril breakdown during room temperature and low temperature storage.Take 31 diffrentially expressed genens which selected from the result of transcriptome sequencing and related to fruit quality deterioration as the object of study,adopt ed the method of real-time quantitative PC R(q RT-PCR)to analyse the changes of expression of those genes during longan pericarp browning and aril breakdown.Correlation analysis between 31 genes expression and pericarp browning index and aril breakdown index was carried out to select the genes which may related to longan pericarp browning and aril breakdown,preliminarily analyzed the mechanism of longan fruit quality deterioration.The main results are as follows:1)During quality deterioration of posterharvest longan,pericarp will turn brown,cell membrane permeability will increase,aril breakdown and TSS decrease.Compared with room temperature storage,low temperature storage can effectively delay the longan pericarp browning rate and the rate of aril breakdown.2)There are differences in pericarp browning rate during different temperature storage among different longan cultivars.During room temperate storage,the pericarp browning rate from high to low in order to ‘Shuiyan ’ above‘Dongbi’and ‘Shixia’ above ‘C huliang’;During low temperature storage,the pericarp browning rate from high to low in order to ‘Shuiyan’ above ‘Dongbi’ and ‘Shixia’ above ‘Chuliang’.3)There are differences in aril breakdown rate during different temperature storage among different longan cultivars.During room temperate storage,the aril breakdown rate from high to low in order to ‘Dongbi ’ above‘C huliang’and ‘Shixia’ above ‘Shuiyan’;During low temperature storage,the aril breakdown rate from high to low in order to ‘Dongbi’ above ‘Shuiyan’ and ‘Chuliang’ above ‘Shixia’4)During room temperate stotage,the pericarp browning rate of ‘Dongbi’ and ‘Shuiyan’ are positively correlated with the express of PME-2,HATP-2,gpm I,PME-1,trpA,PGK-2,and adhp.The Q uantitative RT-PCR assay revealed that there are 12genes--ALG6,GANAB,SWP1,SPS,POD-1,HATP-1,HATP-2,GAPDH,PGK1,maeB,PDHA and cysK—express difference in pericarp between ‘Dongbi’and ‘Shuiyan’during room temperate storage;During low temperate stotage,the pericarp browning rate of ‘C huliang’ and ‘Shuiyan’ are positively correlated with the express ofPME-2,HATP-2,TPI,PGK-2.there are 15 genes—DFR,ANR,ANS,TGA,cysK,aroA,GANAB,MAN1,SWP1,HSP90 B,GAPA,ACO,DLST,ma eB and PDHA—express difference in pericarp between ‘Dongbi’and ‘Shuiyan’during low temperate storage.5)During room temperate stotage,aril breakdown rate of ‘Dongbi’ and ‘Shuiyan’ are positively correlated with the express of GAPDH,Quantitative RT-PCR assay revealed that there are 8 genes—cysK,HSP90 B,ALG6,MAN1,ED,SPS,PGK-1 and maeB—express difference in aril between ‘Dongbi’and ‘Shuiyan’during room temperate storage;During low temperate stotage,the pericarp browning rate of ‘Shixia’ and ‘Dongbi’ are positively correlated with the express ofPGK-2and TGA,and significantly negatively correlated with the express of MAN1、PGK-1 and ACO,there are 12 genes—TGA,cysK,HSP90 B,ALG6,SWP1,SPS,PME-1,GAPA,PGK-1,DLST,maeB and HATP-1—express difference in aril between ‘Shixia’ and ‘Dongbi’during low temperate storage.6)The Metabolic pathways and genes express analyse in longan fruit aging reveled:No matter room temperature storage and low temperature storage,HSP90 B,ALG6,SWP1,GANAB,MAN1,DLST,ACO,GAPA,PDHA,PGK-1,SPS and ED have the same express trend in pericarp and aril.Those genes belong to protein processing in endoplasmic reticulum pathway,TCA pathway,pyruvate metabolism,sucrose and cellulose synthetic,pectin degradation and so on,and their express was affected by temperature—they will up-regulated during room temperate stotage and down-regulated during low temperate stotage.TGA is associated with SAR,it’s expression quantity will up-regulated in pericarp and aril during room temperate stotage.