Effect Of Berry Compactness In Cluster On Anthocyanins Content In Grapes

The influence of berry compactness on the anthocyanin synthesis mechanism of Vitis vinifera L.‘Cabernet Sauvignon’ was investigated.Berries about 25 days after fully blooming were evenly removed manually reducing the number of berries per centimeter of berry-cluster length in a vineyard.Based on the decreasing proportion of berries in one bunch,the treatment was designated as 0,20%,30%,50% and 80%,and each process select 50 clusters to treatment.We focus on discussions about the effect of different cluster compactness on the basic indicators,fruit firmness,reducing sugar content and the anthocyanin content of wine grapes.We investigate the effect of fruit firmness on the accumulation of anthocyanin at the same time.Finally,we verified the effect of berry turgor on fruit quality.The main results are as follows:1.Reducing bunch compactness can promote the fruit development and bear greater color grapes.It can also increase the ripening fruit berry weight.The difference of the berry transect diameter between treatment and control is not significant,while the difference of berry vertical diameter of which is significant.Moreover,the results showed that the content of reducing sugar,soluble solids and total phenol content were all significantly enhanced in the ripening fruit with decreasing compactness.However,the content of titratable acidity showed an inverse change.In summary,reducing bunch compactness can improve the basic quality of the fruit,with the 30% treatment being greatest.2.In order to investigate the effect of cluster compactness on the fruit ripening onset and weather it is related to the fruit turgor,we measured the accumulation of anthocyanins,sugar and the change of turgor during fruit ripening.The results showed that the fruit firmness of treatment decreased before the control,with the accumulation of anthocyanins and sugar in advance.Furthermore,the water content of treatment decreased before control,while the reducing sugar content of all the treatment grapes except 80% treatment were all significantly higher than control in the same period.Meanwhile,reducing bunch compactness significantly improved the total anthocyanins since the ripening onset period,with the 30% treatment has the highest anthocyanins accumulation content.We also investigated the transcript level of the cell wall modification enzyme genes EXP1、EXP2 and XTH during grape development,the result shows that the three transcript levels were upregulated during veraison,which in the treatment were also significantly higher than the same period control.With the reducing of the fruit turgor,the fruit firmness of the treatment were lower than the same period control as well until the mature onset(106 DAB).Then the three genes transcript levels were downregulated with the fruit ripening until they were stable.The transcript levels of the sugar transport protein genes HT1、HT2 and HT3 were higher during veraison,with the reducing sugar content increasing,the transcript levels were downregulated from fruit ripening onset,but the transcript levels of HT1 and HT3 in treatment grapes were still higher than control until the fruit mature.It was concluded that reducing bunch compactness can promote the reducing of fruit turgor and the beginning of the accumulation of sugar and anthocyanins during ripening onset,and the result shows that low fruit turgor was contributed to the accumulation of sugar and anthocyanins.3.The anthocyanin monomer was detected by HPLC – MS.Eleven kinds of individual anthocyanins were detected in the berry skin,with 6 acylation anthocyanins and 5 non-acylation anthocyanins.The main kinds of acylation anthocyanins were acetylation and coumaric acylation anthocyanins.Furthermore,reducing bunch compactness significantly improved the total anthocyanins content in the mature grapes and the proportion of the modification anthocyanins as well,with the 30% treatment berries was the highest.We also investigated the relative expression of the anthocyanin biosynthesis genes such as MYBA、OMT and UFGT,the result shows that the relative expressions of three genes were all significantly higher than control in the same period,with the 30% treatment relative expression was the highest.It suggests that reducing bunch compactness can improve the total anthocyanins content and the proportion of the modification anthocyanins by upregulating the expression of anthocyanin biosynthesis genes.4.The influence of the change of turgor on the ripening process of Vitis vinifera L.‘Cabernet Sauvignon’ was investigated.The film-forming antitranspirant Vapor Gard(active ingredient is di-1-p-menthene,a therpenic polymer,also known as pinolene.)was sprayed to the clusters at onset of grapevine berry ripening.The results showed that the film-forming antitranspirant reduced the water transpiration thus the drop of fruit turgor and berry coloring was postponed under treatment.Meanwhile,the reducing sugar content,soluble solids content and total phenol content significantly decreased compared to control,while the acid content was enhanced under the film-forming antitranspirant treatment.Furthermore,the expression level of the key genes in the fruit anthocyanins synthesis pathway was down-regulated under treatment,as the results,compare to control,the total anthocyanins content and the proportion of the acylation anthocyanins were reduced.Therefore,it was speculated that the treatment might reduce the water transpiration of berry to sustain the berry turgor,and consequently,the berry coloring and the ripening process were markedly delayed.Hence,changing the fruit turgor can be used to regulate the developmental process of grape fruit.On the basis of the study results above,we can reach the following conclusion that reducing bunch compactness can decrease the fruit turgor prior to the control,and the lower fruit turgor was contributed to the accumulation of reducing sugar and the synthesis of anthocyanins.And we speculated that reducing bunch compactness can accelerate the decreasing of fruit turgor by promoting the reduce of water content and the modification of cell wall,then further improve the content of the total anthocyanins and the modification anthocyanins in the grapes,they were all contributed to improving the wine quality.