Effects Of Host Diversity On Phyrophthora Infestans Pathogenicity And Genetic Diversity Of Avr3a And IpiO

Potato late blight is caused by Phytophthora infestans,with the destructive potential continues today,it has become one of the main factors that restricts potato production.Cultivation of disease-resistant potato cultivars has been proved to be most lucrative,efficient and nuisanceless strategies for eliminating these damages.However,resistant cultivars get sensitive easily when facing Phytophthora infestans which evolve rapidly.Distribution of resistant gene in fields is a key factor affecting the evolution of Phytophthora infestans.In this study,isolates of Phytophthora infestans from mixed potato cultivars were inoculated on detached leaf of sensitive cultivar Favorita to test the virulence.The result shows that there are obvious negative correlationship between host diversity and strain virulence,rD5=-0.849*(p=0.016);rD7=-0.873*(p=0.012),and also a obvious negative correlation between host diversity and initial morbidity r=-0.952**(p=0.002).Besides,genetic diversity of avirulence gene Avr3a and ipiO were analyzed,The result shows that there are obvious positive correlationship between host diversity and genetic diversity of Avr3a and ipiO,r=0.884*(p=0.023).Tajima's D neutrality test prove that,the role of directional selection is more outstanding as the host diversity increase.