Seed acquisition
Fifty-three seed accessions, including three accessions ofLeersia , were acquired from seed banks or collected from the field (Table 1). They proceeded mostly (41 accessions) from the International Rice Research Institute in the Philippines. Six accessions could not be traced to a particular source and three accessions were collected during our field expedition. Voucher specimens of these samples were deposited in the herbarium of the Institute of Botany, Chinese Academy of Sciences. Based on their names or field identification, the rice samples belonged to 25 species.