野生ダイズ, 栽培ダイズおよび両種の自然交雑集団の探索, 収集とモニタリング : 秋田県, 茨城県, 愛知県, 広島県, 佐賀県における現地調査から

Prefectures in northern (Akita), central (Ibaraki and Aichi) and southern (Hiroshima and Saga) parts of Japan were visited once to three times during 2004 at the vegetative, flowering and maturing stages of wild soybean (Glycine soja) in order to explore, collect and monitor wild soybean, cultivated soybean and their hybrid derivatives. Among a total of 57 sites, comprising 8, 6, 4, 6, 33 sites from Akita, Ibaraki, Aichi, Hiroshima and Saga prefectures, respectively, we collected 86 bulk samples and 395 individual samples from 29 sites of wild soybean. Among the samples, we found 8, 2 and 1 hybrid individuals at sites, 2004-13, -20 and -39 sites, in Saga prefecture. Characteristics of the hybrids that distinguished them from wild soybean were longer pods (about 4cm, having three seeds), larger seeds (6～12g/100 seeds), thicker stems and weaker vine-twining. At 2004-13 site, only one hybrid individual had a green seed-coat, while seven hybrids had black seed-coat, indicating that the black seed-coat has some selective advantage in natural habitats. One (or a few) hybridization events might have caused the hybrids, because they were distributed over a small area (～2m diameter) at each site. We will focuse on continuous monitoring at each site as well as molecular analysis to better understand natural introgression between cultivated and wild soybeans in Japan