Genetic Variation Among The Alkaline Lipase Producing Mutants From The Genealogy Of Penicillium Expansum

To find the candidate regulation factor for lipase synthesis and provide the basic datafor molecular breeding on Penicillium expansum, the genetic variation among the alkalinelipase producing mutants from the genealogy of Penicillium expansum was analyzed.The random amplification of polymorphic DNA (RAPD) method was used toexamine the genetic polymorphism among series improved mutants of Penicilliumexpansum. A total of 752 RAPD bands were amplified in 11 test strains using 132 primers,among which 298 (39.63%) were polymorphic markers. The average genetic similarityJaccard's coefficient among 11 test strains was 0.8602, and 0.8775 among ten improvedmutants of P. expansum. Phylogenetic analysis based on pairwise genetic distanceaccording to Jaccard's coefficient divided the 11 strains into three groups: group A, B andC. The reference strain CGMCC 3.5175 formed group A; the original strain UN503 andthe mutant FS 1503 composed of group B; and the rest 8 mutants from the genealogy of P.expansum make of group C. The result of principle coordinate analysis (PCA) wasconsistent with that of cluster analysis. The Jaccard's genetic similarity (GS) between theearlier strain S-14 and UN503 was smaller than those of the late strains in the genealogywith UN 503. This suggested that the randomness and undirection of mutation during thestrains improvement may lead to more complicated genetic relationship among the seriesmutants of P. expansum.The lipase gene (PEL) (Penicillium expansum lipase ) and its upstream region ofother improved mutants in the genealogy of P. expansum were amplified and sequencedbased on the known sequence of PEL gene and its upstream region of mutant PF898 fromthe same genealogy. A total of 22 point mutations were detected by comparing the PELgene and its upstream region sequence with a total size of 2292 bp from the 8 mutants ofP. expansum. Among which 9 of 22 point mutations were found within the PEL gene, and4 of the 9 point mutations caused missense mutation in the amino acid sequence of lipase, and 5 point mutations lead to synonymous mutation. The three mutants of FS1503, W468and F1382, of which the PEL amino acid sequence were taken place the missensemutations, showed relative lower lipase activity than those strains of synonymousmutations. One of the 22 point mutations was found in the terminal conservative montageregion in intron 2 of PEL gene of the mutant strain FS1503. 12 of the 22 point mutationswere droped in the 5'-flanking region of the PEL gene. And one of the 12 point mutationswas found in the predictive promoter region Analysis of the upstream region sequence forthe possible transcription factor binding site indicated there are 11 fungi transcriptionfactors could be binded to the upstream region. 2 point mutations, which were found instrains FS1503 and W392, lead to change the binding abiliy of 3 transcription factors ofHSF, PHO4 and StuAp. These mutations might be correlation to the PEL synthesis incorresponding strains and the function of these mutations need to be analyzed in detail.