IDENTIFICATION OF A RESOURCE OF POWDERY MILDEW RESISTANCE IN CUCURBITA MOSCHATA

Abstract

Powdery mildew is one of the most common and widely distributed diseases in gourd vegetable. Cucurbita moschata is an economically important species which is susceptible to the powdery mildew fungus. 'Inbred 112-2', a selected 8-self-generation inbred line, which come from local variety in suburban areas of Xinyang, Henan province, was discovered showing high resistance to the powdery mildew fungus by 8-year field observation. To verify the resistance of 'Inbred 112-2' to the powdery mildew fungus, 'Miben', a widely cultivated pumpkin cultivar in China was used to be control. Sphaerotheca fuligiuea, a main physiological race occurred in C. moschata, was inoculated into leaves of 1-leaf seedling and leaf discs of adult plant respectively. The disease index of adult leaves infected naturally in field, inoculated seedling leaves and inoculated leaf discs were investigated respectively. In addition, scanning electron microscopic (SEM) observation to the normal leaves surface morphology of two tested materials were also performed. The results showed that the disease index of 'Inbred 112-2' were significantly lower than that of 'Miben' in both field natural infection and artificial inoculation, Their corresponding disease index values of 'Inbred 112-2' by three different methods were 0, 28.8 and 7.5 respectively, while those of 'Miben' were 21.7, 47.6 and 38.6. SEM observation showed that 'Inbred 112-2' had more high stomatal density, trichome density and smaller stomata size than those of 'Miben', which contributed to the high antifungal ability. So we draw a conclusion that 'Inbred 112-2' is a promising powdery mildew resistance resource in C. moschata breeding.