Genetic And Environmental Interactions Of Cauliflower Downy Mildew And Molecular Marker Assisted Breeding

Genetic and environmental interactions of Cauliflower downy mildew and molecular marker assisted breeding cauliflower(Brassica oleracea)is a more common economic crop in the yangtze river basin,while cauliflower downy mildew(Peronospora Brassicae Gaumann),as a typical climatic disease,occurs widely in the autumn and winter seasons of the yangtze river basin,causing more serious harm to the yield of cauliflower.In this study,by exploring the field incidence law,fluorescence parameter index,seedling inoculation identification and screening of effective resistance molecular markers of downy mildew disease in cauliflower,a set of identification system for rapid identification of resistance of downy mildew disease in cauliflower was constructed,which provided a theoretical basis for resistance breeding of downy mildew disease in cauliflower.According to the analysis of genotypes and environment of four resistant varieties of cauliflower,Xiamei 80 days,Xueyuan 80 days,830-F,yellow 80 days genotype and environment interaction analysis,by inoculation of cauliflower analysis compared the incidence of four plant cauliflower under environmental conditions,study the effects of genotype,environment and interaction genotype,environment and interaction effects on the incidence of cauliflower downy mildew disease,comprehensive analysis of the correlation between the resistance of downy mildew disease and five meteorological factors.The results showed that genotype was the dominant factor,77.52%～87.04%,followed by environmental effect,12.33%～19.94%,and finally the interaction effect was the smallest,0.63% and 2.54%.The effects of chlorophyll fluorescence parameters on the growth index,disease index and chlorophyll fluorescence parameters of four parents and six hybrid F1 of cauliflower were investigated.The correlation between yield index,cauliflower disease index and chlorophyll fluorescence parameters was compared.The results showed that F_v/F_m and F_v/F_o showed significant difference between parents and F1 generations while F_v/F_o had no significant correlation with the quality of the flower ball,F_v/F_m showed a significant positive correlation with the quality of the flower ball taken together,it shows that F_v/F_m can distinguish the cauliflower with differentsusceptible genotypes and can be used as a parameter index to identify the resistance of the cauliflower.Inoculation experiment of cauliflower material was carried out in the seedling stage.Four cauliflower genotypes were inoculated in the seedling stage of downy mildew of cauliflower.The identification results showed that when the inoculation concentration was 3.5×10~5spores/ m L,inoculation amount was 100 m L,it could accurately reflect the type of disease resistance of each variety of cauliflower varieties and thus obtain a rapid to quickly identify downy mildew of cauliflower and improve the breeding efficiency of disease resistance.Using the above research results,96 cauliflower inbred lines were inoculated at seedling stage,and 34 pairs of molecular marker primers for the resistance of brassica downy mildew were screened,and found that the marker primer s ORA21 had polymorphism in gel electrophoresis compared with the results of inoculation identification at seedling stage,the coincidence rate reached 92.7%,thus obtaining an effective molecular marker that can be used to screen different varieties of cauliflower resistance,which provides an effective way for resistance breeding of downy mildew of cauliflower.