Genetic Diversity Of Pea Root Rot Fungus Fusarium Solani F.sp. Pisi And Pea Germplasm Resistance Screening

Pea Root Rot disease is one of the most important diseases causing devastating damage of global pea production. It has been reported in American, England, France, Sweden, Netherlands, Czech and Korea already. In 1950s, the disease was discovered in Qinghai province of China, and now has been reported in many provinces including Gansu, Ningxia, Neimenggu, Hebei, Fujian, Yunnan and so on. Because of lacking resistant cultivars, the highly virulent variation of the pathogen and noneffective measures of prevention, the disease may aggravate in China and causes serious losses of Pea production in the future. My studies are as follows:1. Fusarium spp. were isolated from the diseased samples of pea root rot collected from 11 provinces including Gansu, Hebei, Ningxia, Yunnan, Fujian, Neimenggu, Jinlin, Sichuan, Anhui, Qinghai and Beijing of China during 2009 to 2010.96 isolates were identified as Fusarium solani f. sp. pisi based on the identification of species-specific primers (104 bp) PCR amplification and morpgology (on PDA and CLA culture)Pathogenicity test of the 96 F. solani f. sp. pisi isolates showed that these isolates can be divided into three types:highly pathogenic, middlely pathogenic and lowly pathogenic. Among the 96 isolates, highly pathogenic isolates occupied 81.3% and distributed in Hebei, Ningxia, Gansu, Yunnan, Sichuan, Anhui, Beijing and Neimenggu provinces. Middle ones occupied 10.4% and distributed in Qinghai and Fujian provinces. Low pathogenicity ones occupied 8.3% and distributed in Jilin, Yunnan and Fujian.Detection of the four pathogenicity genes (PDA1, PEP1, PEP3 and PEP5) in the 96 F. solani f. sp. pisi isolates based on putative strains showed that there are ten types of gene combination (type A:PDA1+PEP1+PEP3+PEP5, type B:PDA1+PEP1+PEP3, type O.PDA1+PEP3+PEP5, type D:PDA1+PEP1, type E:PDA1+PEP3, type F:PEP1+PEP3, type G:PEP1+PEP5, type H:PEP1, type I:PEP3 and type J:PEP5.) in these isolates. The number of each type (A, B, C, D, E, F, G, H, I and J) were 41,45,1,1,1,2,1,2,1 and 1, respectively. Type A, B and C containing four or three pathogenic genes most were high pathogenicity. Isolates of these types occupied about 91% of all and distributed in eight provinces including Anhui, Beijing, Hebei, Neimenggu, Ningxia, Gansu, Qinghai and Sichuan. The other seven types of isolates occupied 9% and distributed in Gansu, Jilin and Yunan priovince. 2. Nucleotide sequences of Nectria haematococca mating population VI (anamorphys was F. solani f. sp. pisi) from GenBank database (http://www. ncbi. nim.nih.gov/) were searched for Advanced Simple Repeat using FastPCR software (Microsoft Visual Studia 6.0). A total of 107 pairs of primers were designed using DNAman software (Version 5.2.2). The primers were used to amplify the genomic DNA of 10 F. solani f. sp. pisi isolates from different areas of China. The PCR production were electrophoresed on 6% denaturing polyacrylamide gel.,24 pairs of them showed polymorphism among these 10 isolates. The number of alleles per locus ranged from 2 to 6 with an average of 4, and the total variant loci were 96.3.24 SSR markers were used to analysis the genetic diversity of the 96 F. solani f. sp. pisi isolates. Using NTSYSpc-2.1 and POPgene32 softwares to analysis the 96 isolates revealled that 24 can amplify a total of 132 variant loci, ranged from 3 to 15 with an average of 5.5. All of the 96 isolates can be divided into 10 (from A to J) groups at coefficient of 0.8. Most of the low pathogenictiy isolates were clustered into a single subcluster.96 isolates are divided into 11 group based on the geography origination, among them isolates from Ningxia province and Gansu province have the maximum coefficient of 0.8536. Corresponding to the geography origination, the genetic distance of isolates from Ningxia and Gansu are the proximal, while isolates from Beijing and Qinghai with genetic distance of 0.8983 are the farthest. The results showed that the. isolates from different areas of China have highly genetic diversity and there is some relationship between the variation and the pathogenicity of the isolates.4. Using the high pathogenicity F. solani f. sp. pisi strain DX-8 and the spore suspension method to select the resistant resources of pea. The result showed that 37 pea cultivars have the scales under or equal 2.5 with the 0-5 disease scale criteria, which occupied 11% of all, cultivars with disease scales of 2.6-3.5 were 142, occupied 40% of all,3.6-4.5 were 62, occupied 18%, the others were 109, occupied 31%.