摘要
Powdery mildew, which called Sphaerotheca phaseoli in Latin, is one of the major diseases of mungbean （Vigna radiata L.） worldwide, causing up to 50% yield losses. Most mungbean varieties grown in Thailand are susceptible to the disease, therefore, new resistant varieties are highly desirable. Three resistant mungbean lines, V4718, V4758 and V4785, were identified from the AVRDC collection. In this study, the authors compared the resistance levels among these 3 lines and tested the allelic relationship among these resistance genes. Three crosses, V4718 × V4758, V4718 × V4785 and V4758 × V4785, were made and the F1 hybrids were selfed to generate the F2 populations and crossed to a susceptible variety, CN72 to generate the F1 × S populations. In the F1 × S and F2 populations, the resistance segregated in a ratio of 3 Resistant （R）：I Susceptible （S） and 15R：IS, respectively for all three crosses. These results indicate that a single dominant gene confers resistance to powdery mildew in each resistant line and these resistance genes are non-allelic. The authors are currently transferring these resistance genes into commercial varieties to provide durable resistance to powdery mildew.
