Species differentiation of two cultivar species in <i>Fagopyrum</i> (Polygonaceae)

Abstract

Due to reproductive isolation, such as self-incompatibility, heterostyly, and higher genetic diversity within populations, the origin and evolution of buckwheat are difficult to study even though there are several cytological studies have been performed. In this study, Fagopyrum esculentum, F. esculentum ssp. ancestrale, F. tataricum, and F. tataricum ssp. potanini were used for karyotype analysis by double-color fluorescence in situ hybridization (FISH) using 5S and 45S rDNA probes. The karyotype analysis revealed that F. esculentum and F. esculentum ssp. ancestrale have the same karyotype formula, 6m+2sm (satellite, SAT). Conversely, F. tataricum and F. tataricum ssp. potanini possessed differing karyotypes, 6m+2sm (SAT) and 6m+1sm+1sm (SAT), respectively. From the FISH analysis, F. esculentum and F. esculentum ssp. ancestrale represented three pairs of 5S and 45S rDNA signals. F. tataricum and F. tataricum ssp. potanini represented a pair of 5S rDNA signals equally. In addition, F. tataricum exhibited two pairs of 45 rDNA signals, and F. tataricum ssp. potanini showed a pair of 45S rDNA signals. Our results were consistent with previous studies suggesting that F. tataricum evolved from F. tataricum ssp. potanini. Additionally, we found that F. tataricum ssp. potanini has the fewest rDNA repeats in the cymosum group. These results can be used as basic cytological information for buckwheat research in the future.