Study On The Effect Of Light And Temperature On Grape Quality And Anthocyanin Synthesis

The color of grape fruit is an important indicator to measure its quality and ripeness,anthocyanin content and components are the main pigments affecting the color of grape fruit,and environmental factors such as temperature and light have an important impact on the synthesis of anthocyanins.In this study,the results of ’summer black’ fruits in the ripening period of seven different cropping periods under facility cultivation and the fruits of two seasons of green fruit,expansion stage,early color change,end color change and ripening period of ’summer black’ under the two-ripening cultivation mode were used as test materials,and the differences in quality and anthocyanin metabolism in the ripening grape fruits and grape fruits in the two cropping stages during development were compared with the changes of temperature and light during the phenological period,and the effects of light and temperature on grape quality and anthocyanin metabolism in the facility were discussed.The results of the study are as follows:(1)The soluble solids content,sugar,acid,flavonoids and anthocyanins of grapes in winter were significantly higher than those in summer,while the weight of single fruit and horizontal diameter were significantly lower than that of summer grapes.Soluble sugar content was negatively correlated with average temperature,soluble sugar content was positively correlated with daily temperature difference,and peel color difference a* was significantly positively correlated with light intensity and average temperature.(2)The anthocyanin types in grape fruits were detected by high performance liquid chromatograph with trihydroxyanthocyanins(Dp,Pg,Mv)and dihydroxyanthocyanins(Cy,Pn).The anthocyanin components and contents in ripe grape fruits at different stages were seasonally specific,and the anthocyanin content in winter fruits was significantly higher than that in summer fruits,and the proportion of trihydroxyanthocyanins / dihydroxyanthocyanins in winter fruit peels was significantly lower than that in summer fruits.The daily temperature difference was significantly positively correlated with anthocyanin content and components,and the average temperature was significantly positively correlated with trihydroxyanthocyanins/dihydroxyanthocyanins.(3)Anthocyanins in grape fruits were mainly distributed on the peel,and with the development of fruits,the anthocyanin content and components showed a significant upward trend,and the accumulation rate of anthocyanins in summer grape fruits was significantly lower than that in winter fruits.From the beginning of color conversion to the end of color transformation,the ratio of trihydroxyanthocyanins/dihydroxyanthocyanins in summer grape peels was significantly lower than that in winter fruits.During ripening,the ratio of trihydroxyanthocyanins/dihydroxyanthocyanins in summer grape peels was significantly higher than that in winter fruits.(4)Based on transcriptome sequencing data,combined with gene expression trend analysis and weighted gene co-expression network analysis,structural genes(PAL,CHS,F3’5’H,F3’H,UFTG)and regulatory genes(MYBA2,WRKY75,b HLH)related to anthocyanin synthesis were screened out,and the expression rules of these candidate genes were analyzed.During fruit development,the expression of upstream structural genes(PAL,C4 H,CHS,CHI,F3H)was consistent with the accumulation pattern of anthocyanins in grape fruit.The downstream structural gene F3’5’H was up-regulated in the peel and down-regulated in the pulp,while F3’H was up-regulated in the peel and pulp,and the difference in the expression pattern of the two structural genes in the two tissues of grapes may be the reason for the histospecificity of anthocyanin components of grape fruit.In the process of fruit development,the regulatory genes MYBA2 and b HLH were up-regulated in the peel and pulp,while WRKY75 was up-regulated in the peel and down-regulated in the pulp.The results of the correlation analysis between structural gene and regulatory gene expression showed that UFTG was significantly positively correlated with regulatory genes MYBA2,MYB90,WRKY75,WRKY22 and WRKY24,and it was speculated that during fruit development,the transcription factors MYBA2 and WRKY75 were upregulated and promoted the synergistic upregulation of the downstream structural gene UFTG,thereby promoting the accumulation of anthocyanins.(5)Nine genes(6 structural genes and 3 regulatory genes)were selected from the candidate genes and verified by q-PCR in summer and winter grape fruits.During fruit development,F3’H,UFTG,ANS,CHS,MYBA2,WRKY75 and b HLH were significantly higher than those in winter grape fruits,while the expression levels of F3’5’H and DFR were significantly lower than those in summer fruits in winter fruits.