Spatiotemporal Variation Characteristics Of Accumulation For Proanthocyanidin And Anthocyanin In Vitis Davidii Foex ’Xiangzhenzhu’

Vitis davidii Foex is a wild grape germplasm resource originated from China.The grapes contain abundant biologically active substances such as proanthocyanidins,anthocyanins and flavonol,especially the content of anthocyanins is significantly higher than vitis vinifera L.At present,there is a lack of systematic research on the spatio-temporal accumulationthe of proanthocyanidins and anthocyanins during fruit development of Vitis davidii Foex.In order to clarify the characteristics of accumulation for proanthocyanidins and anthocyanins in Vitis davidii Foex,this experiment used the main cultivar’Xiangzhenzhu’ as the material to study the synthesis,accumulation and distribution characteristics of proanthocyanidins and anthocyanins in the growth and development of skin,seed and stem,as well as the dynamic changes of synthesis-related genes,to explore the tissue differences of their synthesis and accumulation.The purpose of this study is to provide reference for the improvement and comprehensive utilization of Vitis davidii Foex germplasm resources and the production of high quality grape and wine.The main results of this study are as follows:(1)After veraison,the horizontal diameter and longitudinal diameter of Vitis davidii Foex ’Xiangzhuzhu’ showed little difference,which increased by 5.17% and 3.14%,the weight increased by 24.40%.The contents of soluble solids and titratable acids in grapes changed greatly during the ripening period,and were 18.00 °Brix and 4.31 g/L(calculated as tartaric acid)at harvest,respectively;The growth and development cycle of grape was 198 d.(2)The contents of phenolic substances in Vitis davidii Foex ’Xiangzhuzhu’ showed obvious tissue differences.The content of total phenols,total flavonoids,total proanthocyanidins,and total flavan-3-ols in stem were the highest,and the antioxidant activity was also the strongest.During grape growth and development,phenolics except anthocyanins in the skin showed a trend of first decreasing and then increasing;while anthocyanins accumulated continuously from veraison and the content was the highest at harvest,which was 32.03 mg/g DW.Phenolics in seeds showed a trend of first decreasing and then being stable.(3)The proanthocyanidin characteristics of different tissues in Vitis davidii Foex’Xiangzhuzhu’ were significantly different.The molecular mass and mean degree of polymerization of proanthocyanidins in grape skin were significantly higher than those in seed and stem.In different tissues of proanthocyandins composition,(-)-epicatechin extended subunits are the components with the highest proportion in mole percentage.The content of flava-3-ol monomer in stem was much higher than that in skin and seed.(+)-Catechin and B2 were the highest content of proanthocyanidins monomer and oligomer in skin,while(-)-epicatechin and B2 were the highest content in seeds and stems.(4)The anthocyanins of Vitis davidii Foex ’Xiangzhuzhu’ are accumulated in the skin,and are mainly diglucoside.The delphinidin-3,5-O-diglucoside is the most abundant anthocyanin component,and the content at harvest was 44.53 mg/g DW,accounting for68.07%.(5)The expression levels of genes related to the synthesis of proanthocyanidins and anthocyanins were tissue specific.Structural genes VdF3’H,VdF3’5’H,VdLAR1,VdLDOX,VdOMT,transcription factors VdMYB5 b,VdMYBA1,VdMYBPA2 highly expressed in the early stage of skin and stem.The expression of structural genes VdCHI,VdUFGT,VdGST4 and transcription factors VdMYB5 a in skin and seed after veraison was higher.Structural genes VdCHS2,VdCHS3,VdF3 H,VdLAR2,VdANR and transcription factors VdMYBPA1 were highly expressed in skin and seed at the early stage of development.Correlation analysis showed that VdCHI,VdGST4,VdUFGT,and VdMYB5 a were highly correlated with anthocyanin synthesis,VdDFR,VdF3’H and VdMYBPAR were highly correlated with proanthocyanidin synthesis.(6)In Vitis davidii Foex ’Xiangzhuzhu’,proanthocyanidins in skin mainly exist in the2-18 layer cells of the hypodermis of excoarp.In the seed,it mainly exists in the middle layer of outer integument.And in the stem,proanthocyanidins mainly exist in phloem and the parts connecting pedicle and fruit brush.