Damage Investigation Of Potato Root Rot Caused By Fusarium And Its Pathogenic Identification And ISSR Analysis Of Genetic Diversity In Northwest China

In recent years,the growing area of potato in Northwest China has been increased.Because of continuous cropping problems,the occurrence and harm of various diseases of potatoes has been aggravated year by year.The occurrence of root rot caused by Fusarium spp.was also very serious.It not only restricts the yield of potato,but also affects the quality of potatoes and varieties,which was an important factor restricting the development of potato industry.Fusarium were also a kind of pathogenic with wide distribution;many hosts and strong infective ability.There were also some differences among the pathogenic caused the disease in different areas,which makes it more difficult to control the disease.Based on the above problems and characteristics,the disease investigation,pathogen identification and genetic diversity analysis of potato Fusarium root rot were carried out in Northwest China.The main results were as follows:1.The disease of 61 main potato produced areas was investigated by random survey in Northwest China.The survey shows that the highest incidence of diseases in Ningxia was in Yuanzhou District of Guyuan City;the highest incidence of diseases in Qinghai was in Shenzhong Township of Huangyuan County,with a 30%incidence rate;the highest incidence of diseases in Gansu Province was Tianzhu County,with the lowest incidence rate being Qingcheng County,with a 2%incidence rate;the highest incidence of diseases in the areas investigated in Shaanxi Province was Hengshan County,with a 30%incidence rate.The incidence of diseases in Yining County of Xinjiang was the highest in the five provinces and regions,and the incidence rate was as high as 80%.It was found that the incidence and severity of Fusarium root rot of potato were significantly different in different provinces and regions.2.Through morphology and molecular biology based on ITS and EF-1α sequences,eight species of pathogenic were isolated and identified from plants/potatoes of disease,including Fusarium oxysporum,solani,F.sambucinum,F.acuminatum,F.equiseti,F.redolens.F.tricinctum and.avenaceum.Pathogenicity of pathogenic bacteria was determined.The results showed that all the identified of Fusarium were pathogenic,but the dominant pathogenic bacteria caused the disease were different in different areas.The dominant pathogenic bacteria in Ningxia were F.solani and F.sambucinum,the incidence was 100%and 88.9%.The dominant pathogenic bacteria in Gansu were F.sambucinum,the incidence was 88.9%.The dominant pathogenic bacteria in Xinjiang were F.solani,the incidence was 88.9%.The dominant pathogenic bacteria in Qinghai were F.solani and F.avenaceum,the incidence was 88.9%.The dominant pathogenic bacteria in Shanxi were.oxysporum which incidence was 77.8%.3.The reaction system of ISSR-PCR was optimized by single factor variable method,and the optimum reaction system was established.The primer concentration of 0.6 μmol/L,DNA of 56 ng/ptL and 2×Easy Taq PCR SuperMix of 8μL.The optimized system and 13 ISSR primers were used to amplify the tested Fusarium and NTSYSpc software was used to construct the phylogenetic clustered tree between species and within species.The results showed that there was a certain correlation between the same species of Fusarium spp.and the strains isolated from the same place had close genetic relationship,but it was not absolute.There was a certain correlation.When the genetic similarity coefficient was 0.60,the tested Fusarium was divided into four groups,and these four groups just represented four different Fusarium species.When the genetic similarity coefficient was increased,the number of the tested Fusarium species was also increased.When the genetic similarity coefficient was 0.98,the tested Fusarium species were divided into 56 groups,so was the phenomenon of genetic differentiation within the same Fusarium species.4.The optimum sporulation medium of Fusarium sambucinum was screened and studied.Colony growth and sporulation of Fusarium sambucinum were studied using eight common culture and five new compounded culture.The results showed that WLA culture had the most significant effect on the colony diameter of Fusarium sambucinum,and the other four hai no significant difference,but the growth of colony diameter was better than that of PDA culture.In terms of sporulation,both WLA and OLA culture had a good promotion effect on the sporulation of Fusarium sambucinum.When cultured to the ninth day,the sporulation of WLA culture was reached 84×105cfu/mL.So the WLA culture was the best culture for the cultivation of pathogenic Fusarium sambucinum in the five new compounded culture.