Identification Of Different Potato Germplasm Resources Resistance To Common Scab And Resistance Mechanism

Common scab is one of the main diseases in potato production in recent years and with the increase of planting area,the degree of disease is becoming more and more serious,which seriously affects the production of commercial potato and seed potato,and causes serious economic losses to growers.Disease-resistant breeding is an economical and effective way to solve scab disease,and the resistance identification and disease-resistant mechanism are the foundation of disease-resistant breeding.Therefore,Streptomyce.Scabies(s.scabies),which is the most pathogenic pathogen of potato common scab,was used in this study to identify the resistance of 52 potato germplasm resources by pot inoculation and in vitro potato chip inoculation respectively,and the resistance mechanism of different resistant potato varieties was preliminarily explored,so as to find the resistant varieties and provide theoretical basis for disease-resistant breeding.The main findings are as follows:1.Resistance screening obtained 11 high resistant materials,14 resistant materials,13 susceptible materials,4 heavy susceptible materials and 10 susceptible materials.2.Different resistant potato varieties showed significant difference in tuber characters.The varieties with pink and purple skin color were more resistant to disease.The resistance of the cultivars was related to ripestage,the late ripening cultivars were more resistant to disease,and the early maturing cultivars were more susceptible to disease.The resistance of potato varieties has little relation with the flesh color and wax content of tubers.3.POD,SOD,PPO,CAT,PAL,β-1,3-glucanase increased in different degree in tubers inoculated with common scab,but the activity of PAL β-1,3-glucanase did not change after inoculation.POD activity and PPO activity in tuber of resistant cultivars remained at a high level before and after inoculation,while the activity of POD activity PPO in tuber of susceptible cultivars was relatively low,indicating that POD activity and PPO activity in tuber played an active role in resisting scab infection of potato varieties.SOD activity of susceptible cultivars was significantly higher than that of resistant cultivars before and after inoculation.Resistant cultivars showed a trend of decreasing first and then increasing after inoculation.After inoculated with different resistant potato tubers,MDA content in susceptible varieties increased,and that of susceptible varieties was higher than that of resistant varieties,indicating that cells and biofilm of susceptible varieties were destroyed more seriously.After inoculation,the soluble sugar content of resistant and susceptible varieties increased obviously,and the soluble sugar content of resistant varieties was higher than that of susceptible varieties.The content of proline in resistant and susceptible cultivars after inoculation was significantly higher than that in the control group without inoculation,indicating that scab bacteria promoted the increase of proline content.The soluble protein content of resistant and susceptible cultivars after inoculation was higher than that of the control group without inoculation,but there was no significant difference in soluble protein content between cultivars.In conclusion,POD activity,PPO activity,SOD activity,soluble sugar content,MDA content may be used as auxiliary means of the resistance identification for potato to common scab.