Agronomic Characters Evaluation With MYB Genotype And Haplotype Analysis Of 72 Wine Grape Varieties

The genetic diversity and identification of grape variety resources are the basis for the protection and utilization of grape resources.However,there are many varieties of grapes with inapparent phenotype,and the homonymous phenomena occur from time to time,and the accurate identification of grape varieties is very important.72 wine grape cultivars from different countries and regions were clustered by NTSYS-2.10e using 8 pairs of primers SSR fingerprints in this paper.The clustering tree graph obtained directly reflected the genetic relationship among the cultivars.When the genetic similarity coefficient was about 0.52,they could be divided into four groups.At the same time,it was found that clustering results could not display specific primers and polymorphic markers,which could be used as reference information for cultivar identification,thus limiting the practical application of molecular markers in cultivar identification.Then the polymorphic fingerprints of six pairs of primers were screened out by the manual cultivar identification diagram（MCID）based on SSR molecular markers,and the cultivar identification diagram（CID）of these varieties was drawn which successfully distinguished 72 wine grape varieties.Primers and polymorphic bands for identification and differentiation between any two or more cultivars could be found on the CID map,which might be helpful in the identification of wine grape varieties,the protection of new varieties and the sustainable development of wine grape industry.At the same time,the inflorescence growth and seed setting coefficients of 72 wine grape varieties,as well as common economics traits such as fruit hardness,soluble solids（TSS）,peel color,single grain weight,peel thickness,titratable acid（TA）and juice yield were investigated and analyzed.Statistics show that the hardness,TSS,TA and juice yield of the grape varieties have obvious genetic diversity,and the coefficient of variation is between 0.13 and 0.59.The juice yield has the smallest coefficient of variation.Whether it is Eurasian or European-American hybrids,the seed setting coefficient is mostly 1 spike;varieties with medium-thickness or more skin account for 66%of all varieties;the black variety with the largest variety of peel colors,followed by white varieties,with the lowest percentage of red varieties.When preparing for breeding work,it is necessary to clearly understand the laws of grape genetics and breeding,as well as the production needs of wine grapes to formulate scientific and reasonable breeding goals,and carry out the selection of excellent wine grape varieties.Color is an important part of the appearance quality of grape berries,and it is particularly important for the wine color and quality of wine grapes after processing.Anthocyanins play a major role in the formation of grape peel color.Grape peel exhibits different colors due to the proportion and accumulation level of various anthocyanins.MYB transcription factors are one of the key transcription factors involved in anthocyanin biosynthesis.Studies have shown that the genotypes of two closely linked MYB loci on chromosome 2 play a decisive role in the coloring of different grape varieties.This study used specific primer sequences to identify the genotype and haplotype composition of the MYBA1 and MYBA2 gene loci in 72 grape germplasms.At the same time,the relationship between the identification results and the color was summarized based on the investigation of the fruit color.Through analysis,it is found that purple black or blue purple is the most common in the haplotype composition of grape peel with the composition of HapC-N.In addition,the study also found that the color of the peel is proportional to the number of haplotypes containing the coloring gene.The more haplotypes containing the coloring gene,the closer the color of the peel is to purpleblack or black.By analyzing the genotypes and haplotypes of the two major populations（Vitis vinifera and the hybrids of Vvinifera and V.Labrusca）,we can obtain the haplotype combination types of European and American hybrids are different from Eurasian-colored grapes,The haplotype composition of the most Eurasian-colored grapes is AC-N,and the number of haplotypes of AE1,AC-N,CN and C-RsE1 in European and American hybrid colored grapes is equivalent.For the molecular design breeding of wine grape fruit color traits,the research content of this article will bring sufficient theoretical support.