Study On Inoculation Methods And Preliminary Screening Of Resistant Sources Of Bacterial Spot Disease In Tomato

Bacterial spot disease occurred in the Youjiang river valley area,which is the main producing area of tomato in southern China.In recent years,the disease has been seriously and widely affected all over China,in that case,bacterial spot disease has become one of the most important disease on tomato.In China,there was few studies on this disease,and there was a lack of tomato varieties resistant to bacterial spot disease.Therefore,it is the basic work to identify the resistance of tomato varieties by artificial inoculation.The resistance of tomato plants to bacterial spot disease was affected by tomato varieties,pathogens and environmental conditions.In this study,inoculation methods of seedling and seed were conducted research.According to the characteristics of different inoculation methods,the main influence factors were optimized.The identification of 74 tomato varieties was conducted by using the optimized conditions.The results are as follows:(1)The strain were isolated from diseased tomato sample collected from Napo,Tianyang.It proved to be pathogenic bacteriain accordance with the rule of Hearst,The results showed that the pathogen of tomato bacterial leaf spot disease in Tianyang county was occured by Pseudomonas syringae pv.tomato with the identification methods of culture characteristics,morphological observation,16s rDNA sequence analysis.(2)The comparative study of the 4 commonly used classification standards showed that the disease index under different classification criteria showed linear or power function respectively,and the regression equation between different disease index calculation standards was established.(3)The inoculation methods for tomato seedlings were formulated:The diseases inoculated by leaf penetration or vaccination on seedlings with 3?5 leaves would be better.The inoculating concentration was 1×108cfu/ml,while the ambient temperature was controlled between 19.5??26.7?.After inoculation,the plants should be miosturized for over 60h,and the degree of the disease should be recorded after 14±2days.(4)The optimal seed-inoculation conditions were also established:.The optimum inoculation concentration was 1 X 109cfu/ml.The time of disease investigation was selected at the 25?30days after inoculation.The temperature was maintained at 23-26.7 C.(5)The disease-resistance identification for 74 tomatoes germplasm are carried out with 2 inoculation methods of seed and seedling.The results of the two methods of 26 tomato germplasm were consistent.With the method of seeding inoculation,there were no disease-immuned varieties,resistant varieties were 9,accounting for 12.32%,toleranted varieties were 22,accounting for 30.13%,susceptible varieties 40,accounting for 53.42%,high sensitivity varieties 14,accounting for 18.91%.With the method of seed inoculation,no immune variety were found,resistant varieties were 13,accounting for 17.8%,toleranted varieties were 37,accounting for 50.07%,susceptible varieties 10,accounting for 13.7%,high sensitivity varieties 14,accounting for 18.91%.