Analysis Of SSR Markers Genetic Diversity Of Phytophthora Capsici In Qinghai

In this study,the Capsicum annuum major produce in 6 areas(Xining City,Haidong City,Huangnan Prefecture,Haixi Prefecture,Haibei Prefecture and Hainan Prefecture)were investigated in Qinghai Province.A total of 357 strains Phytophthora capsici were isolated and purificated,choice of which 80 strains of the P.capsici representative as the research object is analyzed.The experiment identified the types of mating type of P.capsici in Qinghai Province,the sensitive to Metalaxyl,Physiological race types,also with DNA genetic markers,analyzes the differences between different areas of P.capsici.The main results are as follows:1.Of 80 strains of the P.capsici were detected,three mating type were determined,there were A1,A2 and A0,among them,the A1 mating type strains,a total of 33 strains,accounting for 41.25% of the total number of under test;A2 mating type strains of 46 strains,accounting for 57.5%;1 strain A0 mating type strains,accounting for 1.25%.No detected A1A2 and A1,A2 mating type strains.2.Among the 80 strains of P.capsici strains,detected 38 strains were sensitive strains,accounting for 47.5% of the total strains,detected 26 strains were intermediate strains,accounting for 32.5% of the total strains and 16 strains were resistant strains,accounting for 20% of the total strains.Some perennial pepper cultivation areas such as Xining,Haidong,detects sensitive strains and strains of intermediate.Some peppers are planted in historically short areas such as Haixi Prefecture and Haibei Prefecture,detects resistant strains and intermediate strains.Three strains were identified in a few areas.3.Using two methods to identify physiological race types of P.capsici in Qinghai Province:(1)The results of the in vitro leaf method for the determination of P.capsici were as follows: Race2 and Race3 were detected,and no Race1 was detected.Among them,Race2 physiological raced and Race2 physiological accounting for 32.6% and 67.4% of the total.(2)The results of the way to fill the root method for the determination of P.capsici were as follows: identified Race2,Race3 two kinds of physiological race,and no Race1 was detected.Among them,there were Race2 and Race2 accounting for 37.5% and 62.5% of the total.The results of the two methods showed that the frequency of Race3 was higher than that of Race2,and Race3 was the dominant physiological race of P.capsici in Qinghai province.4.According to the orthogonal optimization design(L16(44))method,in separate system,the optimal level of the 4 factors was : DNA,Primer,dNTP,Taq Polymerase.The results showed that the optimum concentration of SSR-PCR reaction system was :1.0ng DNA,0.8umol·L-1 Primer,0.5umol·L-1 dNTPs,and 1.0U Taq Polymerase.Among them,DNA has the biggest influence on the PCR reaction,Primers?Taq Polymerase have the bigger influence on the PCR reaction,dNTP concentrations with minimal impact on the PCR reaction.5.30 primers were screenedout form150 primers used for PCR amplification.The range of amplified bands were between 100-2000 bp,the number of bands from 11-19,There are 114 bands were amplified.UPGMA cluster analysis showed that the genetic relationship of 84 samples P.capsici distribution between 0.42 to 0.94,with an average of 0.62,84 samples were clustered into 9 groups at 0.71,among them,The first cluster includes the 20 strains of the six areas as the dominant population.