Analysis Of Pathogenicity Adaptive Variation In Pyricularia Grisea

Breakdown of rice blast resistance is mainly because of the pathogenicity varietyof pathogens. In order to understand the pathogenicity adaptive variation of blastfungus, the biological characters and the difference in genomes of the blast fungusstrians isolated from the successively inoculated strians were analysised and a cDNAsubtractive library was constructed. The main results of this study are as follows:1 The sporulation, germination rate and appressorium formation rate have muchdifference, but the mycelium growth rate has no significant variance amongsuccessively strains by biological characters test.The pathogencity of fouth generationstrains increased than initial strains.The result suggest the pathogenicity of pyriculariagrisea have a adaptive changing process to rice.2 No significant difference was found among the genomes isolated from successivelyinoculatecl strains by RAPD with 500 primers. The result means that there are nodifferences between these strains in DNA level. Or, more primers Were needed.3 A cDNA.suppressive subtractive library was conducted. And 168 uniquenonredundant EST sequence for fourth generation strains not shared by primitivestrains were identified. Among which, 119 EST sequences were found with blastnsimilarity searches in Magnaporthe grisea Database and 49 were not, 150 were foundby similarity searches in GenBank and 18 were not. 117 have been identified inMagnaporthe grisea among 150 EST sequence.The hypothetical proteins were classified by blastX seaches in GenBank. As theresult, 3.2ï¼…EST sequences had the similarity to degradation protein, 15.2ï¼…had thesimilarity to metabolism protein, 32.1ï¼…had the similarity to biosynthesis protein,25ï¼…had the similarity to transporters protein, 15ï¼…had the similarity to other proteinand 12ï¼…had not homologue protein.