Preliminary Study On The Pathogenic Fungi Of Potato Fusarium Wilt

Potato blast is a soil-born disease. In recent years, it has occurred in many potato planting areas of Inner Mongolia, and become more seriously. And now, it has become one of the main factors restricting the development of the potao industry in our region. The characteristic of Potato Fusarium oxysporium are complex, Genetic variability variation and strong resistance. These increase the difficult to prevention and treatment of this disease. In this study, we will isolate and identify The pathogen of Potato blight by morphological and molecular identification, determine the biological characters of Potato blast, test virulence and effectiveness of the pathogen in interior and explore Pathogenic mechanism of toxin.The purpose of this study is to understand occurrence regularity of disease and provide theoretical basis of Control efficacy. Our results as follows:(1) The pathogen was confirmed by morphological and molecular identification; Results of the pathogen of potato blast of Inner Mongolia is three different types at least: F1(F.oxysporum)、F2(F.solani) and F3(F.tricinctum), one of the main pathogen of this region is F1(F.oxysporum).(2) Determine the biological characters of pathogen of Potato blast of the Inner Mong olia region. The results of the study show that, F1mycelia growth and spore ger min ation of the optimum temperature are25℃.The lethal temper-aturee of spore is60℃. The op timal pH is7,most op timal carbon sources is starch. The optimal mycelia growth of nitro gen source is specially designed. Spore germination optimum nitrogen source is pota ssium nitrate; F2mycelia growth and spore germination of the optimum temperature are25℃. The le-thal temperature of spore is60℃. The optimal pH of the mycelia gro wth is six, Spore germination optimal pH of7. For the requirement of mycelia carbon sources is low. It Can a good use of the glucose sugar, starch and Dfruc-tose, the spore germination op ti mal carbon source for starch and glucose.Theoptimal mycelia growth of nitrogen source is ammoniumcar bonate. Theoptimal mycelia growth of nitrogen source is ammonium nit rate; F3mycelia gr owth and spore germination of the optimum temperature are20℃The leth al temperature of spore is55℃. The optimal pH of the mycelia growth is7.Th eSpore ger mination optimal pH is6. The optimal mycelia growth of carbon source is Starch and mal tose. Three of the most popular carbon source are glucose、sugar,and starch,all can make F3spores better germination. Spore germination optimum nitrogen source is pota ssium nit rate; Humidity on the influence of the pathogen spores germinate larger, relative humidity under85%pathogen spores are not germination, in relative humidity was100%th ree kind of pathogen spore germination rate is the highest.(3) Select6kinds of fungicides on three kinds of potato blest Toxicity Mea su rement. The results show that:6kinds of fungicides on mycelia growth in hibitory have different effect.50%thiophanate-methyl(WP) and22.5%imazalil(EC) on the inhibitory of the three kinds of pathogens are very good. EC50of1.69、5.59、5.03、3.60、5.17and1.58μg.mL-1.(4)F1crude toxin and the bacterial suspension and culture filtrate has the same pat ho genic effect on potato tissue culture. Potato seeding with F1crude to xin, root activity de c reased, cell membrane permeability increased, and the changes in amplitude is posi tively correlation with the toxin concentration and processing time. Identification of resis tance test results of the study sho w that, resistance of potato blest,kexin1.is better than Solanum tuber o su m.After these two varieties of potato seedlings of F1crude toxin infection, the PAL and POD activity in the body fist increase and then decrease. And in the process, ke xin1.,a resistant varieties, has two kinds of enzyme acti vity are higher than the Solanum tuberosum. Highly active duration is also relatively long. It can be concluded that POD and PAL activity is related wi th the disease resistance of potato blast.