Abstract:

The genetic diversity of 240 accessions of water lily germplasm resources was analyzed using fluorescent SSR marker；the population structure of water lily resources was analyzed using Structure software and validated by the principal component analysis and cluster analysis. The core germplasm of water lilies was constructed based on the minimum distance step-sampling method and validated by a t-screen. The results showed that a total of 205 alleles were detected in 16 pairs of fluorescent SSR primers，with an average Shannon information index（I）of 0.2036，an average Nei genetic diversity index（H）of 0.1168，and an average effective number of alleles（N_e）of 1.1697，showing rich genetic diversity. The K-value of the optimal number of populations was three，with a small amount of germplasm mixing between populations；the population structure analysis divided the 240 accessions of water lily into three taxa. The method of LDSS was used to sample at percentage of 70%，65%，60%，55%，50%，45%，40%，35%，30%，25%，20%，15%，and 10% of the core subsets，with no significant overall variation in genetic diversity indices. Thirty-six accessions of core germplasm of Nymphaea were finally constructed，accounting for 15% of the initial collection，with the retention rates of I，H and N_e were 117%，118% and 102%，respectively. The t-test showed that the genetic parameters of the core germplasm containing 36 accessions of water lilies were not significantly different from the original germplasm and adequately represented the diversity of the original germplasm.

Key words: Nymphaea, SSR fluorescent marker, genetic diversity, core collection