F1 hybrids dominated zone without backcross and F2 were made by flowering phenology shift of F1 hybrids between intraspecific ecotypes in Imperata cylindrica

Imperata cylindrica Raeusch. is a perennial grass weed and has two ecotypes. The common ecotype has hairy nodes on culm and flowers in May in western parts of Japan, while the early flowering ecotype has glabrous nodes and flowers in April. It means that the two ecotypes are isolated reproductively in western part of Japan. GOT allozyme analysis suggested that hybrids are formed between the two ecotypes in Tohoku region, northern part of Japan. However, the population genetic structure in Tohoku region, for example the existence and ratio of F1, F2 and backcross hybrids, was still unknown. In this study, we clarified polymorphisms nuclear DNA to evaluate distribution of the hybrids, presence of backcross and maternal or paternal parent of I. cylindrica in Japan using RNA-seq analysis.