Optimization Of Inoculation System Of Pumpkin Powdery Mildew And Screening Of Powdery Mildew Resistant Germplasm Resources

Pumpkin is an annual vine herb of Cucurbitaceae and Cucurbitaceae in China.With the improvement of people’s diet structure and the in-depth study of pumpkin nutrition and its health value,the planting area of pumpkin is expanding year by year.However,powdery mildew is prone to occur in areas where pumpkin is planted all year round,and the yield and quality of pumpkin are seriously affected.There are many kinds of pathogen of pumpkin powdery mildew,which are suitable for the environment.However,the germplasm resources of pumpkin powdery mildew resistance are rare.The research progress of pumpkin powdery mildew is slow all the time.In this study,through the identification of the pathogen species of natural disease of pumpkin powdery mildew in Changsha area of Hunan Province,the physiological race was determined,the most suitable inoculation conditions and preservation methods of the physiological race were studied,and the germplasm resources resistant to powdery mildew were screened by using the pathogen,so as to speed up the research process of pumpkin powdery mildew,It laid a foundation for pumpkin breeding for resistance to powdery mildew.The main results are as follows:1.the collected powdery mildew was purified 5 times in pumpkin leaves by living preservation.The new conidia was selected and put on slide.The 3% KOH solution was stained.Under 10x40 times electron microscope,the spores of powdery mildew were oval,and the presence of stained fibrous bodies in the conidia of powdery mildew was determined.It was concluded that Changsha,Hunan The pathogenic bacteria of powdery mildew belong to P.xanthii.2.The DNA of the powdery mildew pathogen was extracted and PCR was operated by the ITS primer of the fungus.The PCR product was gel electrophoresis,and the 2000 bp Marker was used as a control.The band was between 500 bp and 750 bp.The PCR product was sent to the Qing Ke company for sequencing.The sequencing results showed that the PCR product fragment was 522 bp,and the results of the sequencing of the products were reported to the reported powdery mildew.The results showed that the homology of its sequence and that of powdery mildew in Changsha area of Hunan Province was 99%.It was concluded that the pathogen of powdery mildew in Changsha belonged to P.xanthii.3.13 kinds of melon host identification materials are widely used in the world,which have different physiological resistance to different powdery mildew.After inoculation with powdery mildew pathogens in Changsha,the leaves of melon identification host materials itran h,top mark,V é drantais,PMR 45 and nantais oblong appeared obvious white powder spot 10 days later,and after 20 days,the leaves and stem stem of the plants appeared thick white powder layer.According to the resistance of the host to different physiological species,it was judged that the pathogen of powdery mildew in Changsha area of Hunan Province belonged to P.xanthii,and the physiological small species was 2France.4.the temperature,humidity,concentration of inoculated bacteria solution and seedling age were studied under the single factor treatment.The optimal conditions of inoculation were 30,80% humidity,2.5x105-5.0x105 ml-1 and 3 leaf core at seedling age.5.considering the interaction of single factor conditions,the orthogonal experiment design of temperature,humidity,inoculation concentration and seedling age(L9(3)4)was carried out.The optimal treatment was temperature 30,humidity 55%,spore suspension concentration 2.5x105-5.0x105 ml-1 and seedling age of 3 leaves.6.the effectiveness of the method of preserving powdery mildew by Zhang Xiuhua and others was verified by re inoculation in healthy plants after one year of powdery mildew preservation.7.the pathogen of powdery mildew after purification and propagation in Jinshan base of Changsha City,Hunan Province was inoculated on 90 pumpkin materials.Pumpkin was planted in the shed.Spray inoculation was used in five true leaves.The concentration of spore suspension was 2.5x105-5.0x105 ml-1.The disease sensitivity level of each pumpkin was recorded at the plant stage and the disease index was calculated.9 high resistance materials,11 resistant materials,30 intermediate materials,20 susceptible materials and 20 high sensitive materials were selected.