Radish (Raphanus sativus L.), which was originated from China, was an important vegetable belonging to Brassica famiy. It had a long cultivation history and abundant germplasms in China. According to the statistics in 2006, the cultivation area of radish, which was valuable in edible and economy, was at the second place among all the vegetables' cultivation area of our country. Downy mildew (DM) is a worldwide discontrustive disease of Brassicaceae vegetables induced by the (Oomycete Peronospora parasitica)...