Study On Identification Of Physiological Races And Physiological Biochemical Character Powdery Midew Of Melon For Resistance

In this paper, melon powdery mildew pathogen in the main producing areas of Gansu was collected and identified. The changes of defense-related enzyme activity and physiological and biochemical metabolites of melon varieties with different resistance for mildew pathogen before and after inoculated with bacteria, and leaf structure and dynamics of wax quality content were study in the paper. The results indicated that:1.In the main producing areas of Gansu Province,25 melon powdery mildew pathogens were collected. The results showed that melon powdery mildew pathogen of main producing areas in Gansu Province were S.fuliginea race 1 species and races 2US by microscopic observation and differential host international common powdery mildew inoculation. And race 1 species was the dominant race.2.4 melon varieties were chose to inoculate S.fuliginea species race 1 on leaves, and cell defense-related enzyme activities were determined. The results show that the changes of POD, PAL, SOD and CAT activity in plants after pathogen inoculation had a certain rules.4 enzyme activities increased and then decreased after pathogen inoculation and the resistant varieties had a higher activities and higher increase rate than susceptible varieties. That indicated that the activity of these enzymes was correlated with resistance, but there were also exceptions performance.3. leaf wax content results showed that wax content of two resistant varieties was significantly higher than the susceptible varieties, but flavonoid and total hydroxybenzene content of Prynne honey was significantly higher than susceptible varieties. Stomatal density of resistant varieties was more than susceptible varieties, and was relatively small. That could reduce the opportunity of Powdery Mildew infection. These results indicated that different varieties with different resistance mechanisms and structural resistance may be highly resistant varieties played an important role. The waxy leaf thickness of two resistant varieties PMR-5 and Planters Jumbo played a decisive role in resistance to disease or not. Although Prynne honey and Yellow River honey 3 had the similar wax content, the higher content of flavonoid and total phenol content in Prynne honey was the reason for that Prynne honey had a better resistance than the Yellow River Honey 3.4. The changes and difference of soluble protein, soluble sugar, proline, chlorophyll content didn't have a relevant links with the resistance.