The diversity of traditional Japanese and Taiwanese eggplant cultivars using SSR markers and fruit characteristics

Eggplant (Solanum melongena L.) originated in the eastern region of India and has been cultivated in Japan since 734 AD. A variety of fruit shapes such as round, ovoid, and long are found in Japan and Taiwan. In this study, we investigated the fruit shape and genetic diversity of 156 traditional Japanese and 30 traditional Taiwanese eggplant cultivars preserved in a Genebank Project in Japan. We analyzed their relationships and estimated their population structure. Fruit shape was classified based on 23 measurements obtained from image analysis using the Tomato Analyzer software. The principal component analysis suggested that the Taiwanese cultivars tend to have smaller fruit diameter and fruit length compared to the Japanese cultivars. In addition, we chose 10 SSR markers and genotyped by fragment analysis, and the UPGMA-method molecular to generate the phylogenetic tree. The phylogenetic tree was divided into two clades: Cluster I that included the cultivars from both regions and Cluster II that mainly included the Japanese cultivars. A STRUCTURE analysis was performed to estimate the population structure of the cultivars. As a result, four populations were identified. The Japanese cultivars were classified into Pop I, II and III, and the Taiwanese cultivars into Pop I and IV. In conclusion, for Japan and Taiwan there are many cultivars with a wide range of fruit shapes such from round to long with different genetic diversity. It is important to conserve these traditional cultivars.