No abstract

Longan is one of the most economically important fruits of Asian countries belonging to the family Sapindaceae. Essentially, there is a lack of fundamental karyological data on different cultivars in longan although the whole genome of longan has been successfully sequenced. This study is the first to report the chromosome numbers and karyotypes of nine cultivars of the genus Dimocarpus cultivated widely in the northern regions of Thailand. These cultivars are Chompoo, Haew, Phuangthong, Thao, Jumbo, Phuen-Mueang, Pumateenkong, Chuliang (China), Kohala (America), and one of them (Thao, Dimocarpus obtusus, Lithanatudom & Chaowasku, comb. et stat. nov.) is considered as a rare species found in Thailand. The somatic chromosome number of cells derived from the root tip collected from the air layering branch of all cultivars was determined as 2n=2x=30. All cultivars showed a predominance of metacentric chromosomes in each karyotype indicating their symmetric nature. The karyotype of these cultivars was placed into categories 1B and 2B based on Stebbins classification. In addition, we analyzed the scatter diagrams of asymmetry indices, UPGMA dendrogram with fruit morphology, and PCoA graph together with the karyotypic relationship, and overall, the results revealed that all cultivars of the genus Dimocarpus examined can be divided into two major groups.