Ethnobotanic and genetic diversity of sugarcane in French Polynesia
Background: In French Polynesia, traditional tō (Saccharum officinarum) have been re-exploited in the recent years to produce organic certified rum. Former botanists have described the sugarcane which were spread by Polynesians during their migrations of the Eastern Pacific. One of them, referred by botanists as Otahiti was the main cultivar grown for sugar production until the 1880s. Methods: Between 2013 and 2017, we collected 15 sugarcane accessions in the Society Islands and examined their taxonomic status to establish the correspondence with those described by former botanists. Nine morphological traits were repeatedly measured including stalk colour, tillering, stalk height, stalk diameter, and internode lengths. We also analyzed them using flow cytometry, PCR markers and in one case molecular cytogenetics. Results: The results showed 4 modern hybrids cultivars, 9 traditional S. officinarum and one intergeneric hybrid between S. officinarum and the wild genus Miscanthus floridulus, Tō 'ā'eho. Among the traditional S. officinarum sugarcane cultivars, we suggested that Polynesian sugarcane called Tō 'irimotu and Tō re'are'a could correspond to Otahiti. Conclusions: The studies of processing characteristics also revealed the high Brix of the Tō 'ā'eho and its potential for producing rum. These types of hybrids support the hypothesis of Pacific being a satellite center of sugarcane diversity.