Analysis of suspected synonyms of ‘Baco Noir' and ‘Niagara' by SSR markers and morphology

Abstract: 【Objective】Grape is one of the most important fruit crops in the world. It is widely used for wine, table grapes, raisins, juice and the grape healthy products have also been produced in recent years. Vitis vinifera L., which was originated from Europe and West Asia, is the only species cultivated extensively around the world. China has a long history of grape cultivation. Viticulture spread along the ancient Silk Road and it reached China in the second century A.D., and the Catholic Church replaced the Romans in expanding grape cultivation in the mid-late 19 thcentury. However, after the introduction of grapes into China, the original names of some varieties were lost, and were given new names leading to synonyms and homonyms. Therefor the true identity of the cultivars is essential, and will contribute to effective management of germplasm repositories and the protection of breeders' rights. Simple Sequence Repeat (SSR) has been proved to be the efficient for the identification of germplasms. The objective of this study was to identify the true identity of two groups of suspected synonyms in southwestern China by both morphological and molecular characteristics.【Methods】The genomic DNAs of‘Niagara'‘Guankouputao'‘Yunnanshuijing'‘Guizhoushuijing'‘Baco Noir'‘Cizhongjiaotangputao'and‘Yanjingheizhenzhu'were extracted from young leaves using the Plant Genomic DNA Kit according to the manufacturer's instructions. 38 pairs of fluorescence-labeled SSR markers were used, such as VrZAG62, VrZAG79, VVS2, VVMD5, VVMD7, VVMD25 and so on. The PCR reaction was carried out in a 20 μL volume containing 10 μL 2×T5 Super PCR Mix, 1 μL primer (each) (10 μmol · L^-1) , 1 μL template DNA (50 ng · μL^-1) , 6 μL ddH2 O. The PCR amplification was conducted under the following thermal conditions: 3 min at 98 ℃ for initial denaturation, followed by 35 cycles of denaturation at98 ℃ for 10 s, annealing at optimum Ta for 10 s, 72 ℃ for 30 s, and a final extension at 72 ℃ for 2 min. The end reaction was held at 4 ℃. The PCR amplified products were separated by using capillary electrophoresis in an ABI 3730 xI DNA Analyser. An internal size standard (GeneScan-500 ROX) was adopted to estimate the approximate molecular weights of the amplified products. Finally, peaks were shown by size and height with Gene Mapper v3.2 software.【Results】DNAs from all of the samples were successfully amplified using each of the 38 SSRs with high polymorphism. We studied the genotype data with the profiles of capillary electrophoresis. We found that there were only two distinct genotypes in 7 grape samples by analyzing the 38 SSR loci. The genotype of‘Guankouputao'‘Yunnanshuijing'and‘Guizhoushuijing'is same as that of‘Niagara'.‘Meanwhile'‘Baco Noir'‘Cizhongjiaotangputao'and‘Yanjingheizhenzhu'owning the same genotype. Furthermore, we also conducted morphological trait survey. We found that the morphological characteristics of‘Guizhoushuijing'‘Yunnanshuijing'‘Guankouputao'were similar to those of‘Niagara': the young shoot was green-yellow in colour, the tender leaf was grey-green, the mature leaf was dark green, the berry skin colour was chartreuse, the berry shape was near round, and the flesh had an intense strawberry fragrance with a soft texture as well as high juice content and so on.‘Cizhongjiaotangputao'and‘Yanjingheizhenzhu'had similar morphological characteristics to‘Baco Noir': the young shoot was dark green in colour, the tender leaf was green-yellow, the mature leaf was dark green, the berry skin colour was purple black, the berry shape was near round, and the pericarp was thick and so on.【Conclusion】‘Cizhongjiaotangputao'‘Yanjingheizhenzhu' and ‘Baco Noir' may be synonyms, and ‘Yunnanshuijing'‘Guizhoushuijing'‘Guankouputao'and‘Niagara'may be synonyms. Finally, the identification of homonyms and synonyms would help us to clearly identify germplasm sources and contribute to the use of germplasms.