Genetic diversity of Sicyos angulatus in central and north‐eastern Japan by inter‐simple sequence repeat analysis

Abstract

SummaryFor the development of effective procedures to control invasive plants, it is necessary to learn about their mechanism of spread, for which an understanding of the plant’s genetic variation may be important. Sicyos angulatus is a widespread and invasive weed that grows among forage crops and natural vegetation in Japan. Inter‐simple sequence repeat (ISSR) genotyping was used to detect the regional patterns of genetic variation of S. angulatus in its introduced range in Japan. The goal of this research was to assess the introduction dynamics and mechanism of spread of S. angulatus in Japan. Four screened ISSR primers produced 15 reliable bands, and 12 of these were polymorphic among six areas in central and north‐eastern Japan. The analysis of molecular variance (amova) revealed that 88.4% of genetic variation occurred within areas rather than between the two regions (1.1%), or among areas within regions (10.5%). While the total gene diversity among areas (Ht) was 0.1684, the coefficient of gene differentiation was low among two geographically distinct regions (Gst = 0.053). The genetic diversity indices (h = 0.116; I = 0.173) of the Fuji river area, assumed to be near the first introduction site, were not higher than other areas (total h = 0.165; total I = 0.263). In contrast, those of the Chikuma river and Tenryu river areas were relatively high (h = 0.173 and 0.187; I = 0.276 and 0.277 respectively). The Mantel test showed no significant correlation between geographical and genetic distances. These results suggest multiple introductions from the same gene pools into both central and north‐eastern regions of Japan.