Southern analysis of chestnut rose STK genes. Lane 1, 3, 5: Rosa roxburghii cv. Guinong No.6 which is resistant to powdery mildew disease; Lane 2, 4, 6: R. roxburghii cv. Guinong No.5 which is susceptible to powdery mildew disease. The DNAs were digested with Hin dIII. DNA size markers (ë/Hin dIII) are indicated to the left of the image.