1. National Research Institute of Brewing, 3-7-1, Kagamiyama, Higashihiroshima 739-0046, Japan.
2. Corresponding author. Phone: +81-82-420-0812. Fax: +81-82-420-0803. E-mail: okuda@nrib.go.jp
3. Institute of Genetic Resources, Faculty of Agriculture, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan.