Optimization Of The Condition Of Spore Inducing For Phytophthora Capsici And Development Of SNP Maker For Resistance Gene Of Phytophthora Blight In Pepper (Capsicumannuum)

Capsicum annuum is an important kind of vegetables and spices,which is widely cultivated all around the world,In our country,Phytophthora blight caused by Phytophthora capsici has caused severe impact on the production of pepper.Due to the wide host range of the Phytophthora capsici and the long term survival in the soil,along with the presence of fungus physiological races,combined with the chemical prevention and control effect is not ideal,thus selecting and breeding disease-resistant varieties can effectively reduce the dangers of pepper blight.Firstly,this study has taken Phytophthora capsici Leon as material to study the influence of several factors during the process of mycelial growth and spore production,explore the best condition for spore production,the study isaimed at optimizing the process of fungus cultivation and zoospores production and lay a foundation for pepper blight resistance material identification.Then the study has taken resistant materials G43,G44,susceptible materials G29,G34,G35 and the hybrid F2 population of G43 and G35 as research material,according to the laboratory previously acquired 72 strips differentially expressed gene sequence which have high homology with wild potato late blight resistance genes,we designed primers on the basis of the SNP site,and experiment verification was done in material of resistant and susceptible materials and the the hybrid F2 population of G43 and G35,in order to obtain the SNP molecular markers of resistance genes to Phytophthora blight.The results are as follows:1.The fungus cultivation condition was optimized,collected more motile spores.By researching on the influence of factors during mycelial growth and spore production we found that 5%of the Vg medium,5 days dark treatment is most suitable for growth of hypha and sporangium,we also found that adding water have obvious promoting influence in the formation of zoospores than anhydrous conditions.2.Using 73 pairs of primers to do Polymorphism screening between resistant and susceptible materials,the primers were designed from differentially expressed resistance sequence of SNP sites between the resisitant sequence and the susceptible one's our laboratory had previously.we found 4 pairs of polymorphism SNP marker,the polymorphism rate was 5.48%.The four polymorphism SNP marker are AS-56-4 primer which was designed according to the different sequence Ca21394,AS-31-1 and AS-31-2 primers were designed according to the different sequence Ca14076,AS-32-2primers was designed according to the different sequence Ca14360.3.Doing identification in the hybrid F2 population from G43 and G35,using the above four pairs of primer,we found that AS-56-4 can not amplify polymorphism bands in 4,5,11plant,but have polymorphism bands in the rest of the nine plants.AS-31-1,AS-31-2 and AS-32-2primers can not amplify polymorphism bands in 6,9 plant,but have polymorphism bands in the rest of the ten plants.We can presume that Ca14076 and Ca14360 corresponding to AS-31-1,AS-31-2 and AS-32-2 are likely to be on the same gene or on two genes which are close llinked.Each one of the 12 plants can amplify at least one polymorphism band,most of them can amplify several polymorphism bands,from this we can infer that resistance to Phytophthora blight is controlled by multiple genes.4.Using the above AS-56-4 primer to do PCR in resistant and susceptible materials and parts of their F2 population,we found the amplification result can reach high consistency with field identification,reaching to 95.45%,developed SNP molecular marker to identify resistant material.