1. National Food Research Institute, Ministry of Agriculture Forestry and Fisheries, 2-1-2 Kannondai, Tsukuba 305-8642, Japan; National Agriculture Research Center, Ministry of Agriculture Forestry and Fisheries, 2-1-2 Kannondai, Tsukuba 305-8666, Japan; and Chugoku National Agriculture Experimental Station, Ministry of Agriculture Forestry and Fisheries, Nishifukatsu 6-12-1, Fukuyama 721-8514, Japan