Molecular Marker-based Identification Of Potato Germplasms And Association Analysis With Important Biological Traits

In China, the process of potato breeding can be divided into several stages, from initially introduction and identification of elite varieties to the currently molecular-assisted breeding, and the ultimate goal is to breed up high quality potato varieties with better agricultural characters. With understanding the potato germplasm resources, breeders can accelerate the breeding procedures. In this research, genetic diversity of cytoplasm and nucleus genomes of potato germplasms conserved in Yunnan Normal University were detected by using molecular marker detection method. Partial representive cultivars were further employed to conduct the association analysis between their cytoplasm types and major agronomic characters. Combining morphology observation with cytoplasm and nucleus diversity detection, the genuineness of potato variety C-88 from different potato areas of Yunnan province was verified. The main results were as followings:1. Four primer pairs of chloroplast DNA and two primer pairs of mitochondrial DNA were used to test cytoplasm types of 87 tetraploid and 9 diploid potato germplasms. Seven cytoplasm types, named W/α [D], W/γ [D], W/α, W/γ, T/β, P, and A/β, were found. Almost all imported potato varieties shared the same cytoplasm type which is the representing type T/β of common potatoes; however, there were three cytoplasm types, W/α [D], T/β and A/β, were detected in Yunnan landraces of potato. All advanced clones of potato late blight resistance Population B, established by Yunnan Normal University, had the same W/α[D] cytoplasm type, which were obviously defered from major cultivars cultivated in domestic and abroad.2. Based on SSR marking technology, a fingerprinting database of 96 potato cultivars was constructed. It could be divided into two groups, namely the wild type(Wild, W) or common cultivated potato type(Tuberosum, T) according to their cytoplasm types. Comparatively, the group harboring W type cytoplasm showed more divergent than that having T type cytoplasms.3. With the association analysis between cytoplasm types and some important traits among part of potato varieties, maturity periods, late blight resistance and starch contents of W type varieties(including Andigena,A type) were significantly difference to those of T type ones. Generally, the yield of cultivars having W type cytoplasm was significantly higher than that of T type cultivars.4. A total of 143 samples of putative cooperation 88 collected from the major potato areas in Yunnan province were verified for their genuineness through morphology observation, cytoplasm and nucleus genomes diversity detection methods. We found that only one sample was differed from the reference cooperation 88 either based on the results of morphology observation or the results of cytoplasm type detection. However, there were 23 samples showed different SSR genotypes when compared with the reference cooperation 88.Above results demonstrated that cytoplasm typing could be a useful tool for parents selection and marker-assisted selection. SSR marker based detection methods used in the research could reveal the genetic diversity of materials used, but it needs to be further improved while applied to the genuineness verification of potatoes.