| The quality of wine grape raw materials directly determines the quality of its wine.Due to the dry climate and lack of rain in the Hexi Corridor of Gansu province,the grape ripening period has sufficient light,which leads to the rapid accumulation of sugar,the short ripening period and the limited accumulation of secondary metabolites,resulting in a serious decline in the quality of grapes during the harvest period.Methyl jasmonate?MeJA?,as an important plant hormone,plays a key role in resisting pathogens,and MeJA can also delay the process of plant ripening and affect the accumulation of plant secondary metabolism.In this study,the white variety Italian Riesling?Vitis vinifera L.cv.?wine grapes was used as raw material to study three MeJA treatment methods?T1: berry soaking,T2: foliar spraying and T3: whole plant spraying?on gene expression and metabolite synthesis in different phenological stages?S1: later of veraison,S2: Middle of maturity and S3: harvest period?of grape,and to explore the molecular mechanism of exogenous MeJA on the quality regulation of Italian Riesling wine grape.The main results are as follows:1.The determination of primary metabolites?glucose,fructose,pH,organic acid and total acid?in samples of different growth stages after different MeJA treatments.The results showed that there was no significant difference in the content of primary metabolites among the samples when the samples were taken at the same growth stage,but there was a significant difference between the content of primary metabolites in each treatment on the same sampling date?p < 0.05?.2.Transcriptome sequencing results showed that the expression of grape berry transcriptome changed after MeJA treatment,compared with CK,690,95 and 417 differentially expressed genes?DEGs?were found in T1,T2 and T3 treatments,respectively.The results of GO enrichment analysis showed that monoterpene compounds were enriched in three different MeJA treatments in both biology and synthesis.Combined with KEGG enrichment analysis and cluster coexpression pattern analysis,it is found that MeJA significantly affects the linoleic acid and ?-linolenic acid metabolism pathway,monoterpene-terpene biosynthetic pathway,phenylpropaneflavonoid metabolism path.In addition,MeJA treatment can induce the differential expression of JA biosynthesis and signal transmission related genes in grape,including LOX2 S,AOS,OPR,JAMT,JAZ,MYC2 and other genes are up-regulated,while AOC is down-regulated,and fruit soaking treatment was more obvious.3.The results of the determination of the content of monoterpenes in the grapes showed that after exogenous MeJA treatment,as the grape gradually matured,the overall monoterpenoid content in the grape showed an overall upward trend,compared with the CK.The content of monoterpenoid in the grapefruit after exogenous MeJA treatment Significantly?p<0.05?increased,and the number of monoterpenes in grapes increased,that is,exogenous MeJA treatment can induce the accumulation of monoterpenes in grapes.In the S1,the total content of monoterpene compounds in the T1,T2,and T3 treatments was increased by 9.3,1.5,and 4.4 times compared to the CK.In the S2,the T1,T2,and T3 treatments were increased by 5.7,1.5,and 2.5 times than the CK.During the S3,T1,T2 and T2 were increased by 5.3,1.2 and 2.6 times,respectively,and the accumulation effect of monoterpene compounds after T1 treatment was the best.Exogenous MeJA induced the upregulation of DEGs in the terpenoid and monoterpene synthesis pathways,leading to the accumulation of monoterpenoids,after MeJA treatment,the DXS,HMGCR,TPS14 and ?-terpineol synthesis genes in the monoterpene synthesis pathway the expression level was up-regulated,the effect of fruit soaking treatment was the best.4.The results of non-anthocyanin phenolic compounds showed that a total of 12 phenolic acids,13 flavonoids and 5 flavan-3-ols were identified.Exogenous MeJA treatment can significantly?p<0.05?promote the accumulation of non-anthocyanins.Among them,the treatment effect of T1 treatment is the best,the total content of flavonoids,phenolic acids and flavan-3-ols were increased by 87.61%,57.80% and 180.37% compared with the CK.T3 treatment is followed by an increase of 55.39%,43.31% and 79.36%.T2 treatment only increased by 40.31%,9.45% and 47.57%.Combining this result with transcriptome data analysis showed that after MeJA treatment,11 genes related to the flavonoid pathway were differentially expressed,7 of which were up-regulated.12 genes related to the phenylpropane pathway were differentially expressed,5 of which were Increase expression.In addition,the differential genes encoding enzymes such as HCT,COMT,LAR,and UGT72 E were up-regulated by exogenous MeJA treatment,which resulted in the accumulation of non-anthocyanin phenolic compounds,and the gene expression was T1 > T3 > T2> CK.5.Using the WGCNA method,30812 genes were selected from 12 grape samples to construct 12 co-expression modules for detecting the relationship between MeJA-induced grape transcriptome and secondary metabolite traits.The brown module?kMEbrown?was finally determined as a co-expression module related to the content of secondary metabolites?monoterpenes,flavonoids,phenolic acids and flavan-3-ols?.Functional enrichment analysis showed that there were significant differences in gene interactions within the brown module?p<0.05?.The co-expression module constructed by Cytoscape software was viewable,and the core gene was identified as VIT11s0037g00570.In summary,the expression of some genes in the transformation transcriptome of grapes of Italian Riesling wine grapefruit treated with exogenous MeJA in different ways has changed.The main functions of the differential genes are enriched in the linoleic acid and ?-linolenic acid metabolism pathway,monoterpene-terpene biosynthetic and phenylpropane-flavonoid metabolism pathway.Exogenous MeJA can induce the accumulation of monoterpenoids and nonanthocyanin phenols in grapes;and the effect of soaking the fruit is the best.It provides abundant data resources and molecular theoretical basis for exogenous MeJA to induce grape secondary metabolites. |
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