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The conidia of Pyricularia oryzae were cultured on barley grain medium for 17 days in this study. Two hundred milliliters of barley grains of each tested strain were cultured in a 500 mL Erlenmeyer flask. The conidia were eluted with 300 mL of sterile water from the cultivated barley grains in each flask. The barley grains were placed in aluminum plates for continued cultivation. The conidia were eluted with 48 h of interval culture, and the elution method used each time was the same as that used for the first elution. All the tested strains could be eluted 6 times; thus, we obtained a large number of conidia. The numbers of conidia produced in the elutions of all the strains were significantly different, with the smallest number produced in the first elution, followed by a gradual increase and then a gradual decrease after reaching the peak; the number of conidia produced in the sixth elution, that is, the final elution, was also low. The total number of conidia and the total number of effective conidia differed among the strains. A large number of effective conidia can be obtained by using the method described in this study, and much time can be saved because the conidia can be eluted six times in one culture cycle. [ABSTRACT FROM AUTHOR]

The objective of this study was to preliminarily analyze the differences in pathogenicity and physiologic races between Pyricularia oryzae isolates from indica and japonica rice varieties. Five to 7 isolates of P. oryzae from indica and japonica, having good sporulation capacity, were screened out in each experimental year. To determine the pathogenicity of P. oryzae, different kinds of rice varieties were inoculated with mixtures of indica and japonica isolates. A total of 46 isolates, including 23 indica isolates and 23 japonica isolates, were screened out in four years. In total, 1252 rice varieties, including 490 indica, 296 japonica and 466 indica-japonica hybrid rice varieties, were inoculated. Our results suggested that the degree of disease was more severe in most indica varieties infected with indica isolates than in those infected with japonica isolates. That is, indica isolates were more inclined to infect indica varieties. A majority of japonica and indica-japonica hybrid rice varieties infected with japonica isolates showed more severe infection than those infected with indica isolates. In other words, japonica isolates more easily infected japonica and indica-japonica hybrid rice varieties. The differences in quantity among the varieties indicated high resistance to rice blast in the corresponding kinds of rice inoculated with indica and japonica isolates, fully explaining the above viewpoint. Most of the 23 indica isolates belonged to indica races. Among the 23 japonica isolates, half were indica races and half were japonica races. In addition, there were significant differences between the isolates selected in the first two years and those selected in the second two years. The isolates in the first two years were all of indica races, and those of japonica races all appeared in the second two years. The results showed that the race of isolates shared little association with the kind of rice variety collected but was associated with the year of neck blast sample collection. [ABSTRACT FROM AUTHOR]

The peroxisomal matrix proteins involved in many important biological metabolism pathways in eukaryotic cells are encoded by nucleal genes, synthesized in the cytoplasm and then transported into the organelles. Targeting and import of these proteins depend on their two peroxisomal targeting signals (PTS1 and PTS2) in sequence as we have known so far. The vectors of the fluorescent fusions with PTS, i.e., green fluorescence protein (GFP)-PTS1, GFP-PTS2 and red fluorescence protein (RFP)-PTS1, were constructed and introduced into Magnaporthe oryzae Guy11 cells. Transformants containing these fusions emitted fluorescence in a punctate pattern, and the locations of the red and green fluorescence overlapped exactly in RFP-PTS1 and GFP-PTS2 co-transformed strains. These data indicated that both PTS1 and PTS2 fusions were imported into peroxisomes. A probable higher efficiency of PTS1 machinery was revealed by comparing the fluorescence backgrounds in GFP-PTS1 and GFP-PTS2 transformants. By introducing both RFP-PTS1 and GFP-PTS2 into Δ mgpex6 mutants, the involvement of MGPEX6 gene in both PTS1 and PTS2 pathways was proved. In addition, using these transformants, the inducement of peroxisomes and the dynamic of peroxisomal number during the pre-penetration processes were investigated as well. In summary, by the localization and co-localization of PTS1 and PTS2, we provided a useful tool to evaluate the biological roles of the peroxisomes and the related genes. [ABSTRACT FROM AUTHOR]