Pathogenicity, Mating Ability and DNA Restriction Fragment Length Polymorphisms of Pyricularia Populations Isolated from Gramineae, Bambusideae and Zingiberaceae Plants

Abstract

Eighty-five Pyricularia isolates were collected from 29 host species of Gramineae, Bambusideae and Zingiberaceae plants sampled in Brazil, Uganda, Ivory Coast, India, Nepal, China, Indonesia and Japan. These isolates were compared on the basis of pathogenicity, mating ability and restriction fragment length polymorphisms with single-copy DNA probes. Based on the pathogenicity to eight differential gramineous plants, these isolates were classified into seven pathotypes : finger millet type, foxtail millet type, common millet type, rice type, crabgrass type, Italian ryegrass/ weeping lovegrass type, and non-cereal/grass type. Genetic variation among these isolates was assessed by RFLP analysis with two restriction enzymes and nine single-copy DNA probes isolated from a finger millet strain. An UPGMA dendrogram based on the RFLPs revealed that the 86 isolates could be classified into seven major groups. Isolates from cereal crops (finger millet, foxtail millet, common millet, wheat and rice) and a grass, Brachiaria plantaginea, were clustered into a single group. They were further divided into six subgroups corresponding to the pathotypes. Among cereal crop isolates only an isolate from pearl millet was located into a different group. The remaining isolates were clustered into five groups designated as the crabgrass group, the buffelgrass and jungle rice group, the rice cutgrass, knotroot bristlegrass and Setaria tomentosa group, the bamboo and bamboo grass group and the Zingiber mioga group. The isolates from cereal crops were generally capable of mating with finger millet strains and constituted a closed mating compatibility group. These results suggested that the isolates from cereal crops form a single group with a common ancestor although they are pathogenic to taxonomically diverse plants. A combined analysis of the pathogenicity and genetic similarity suggested that the transmission of M. grisea isolates occurs in natural agroecosystems between finger millet and Eleusine africana, goosegrass or Bambusa arundinacea, between foxtail millet and green bristlegrass, and between rice and tall fescue, Italian ryegrass, sweet vernalgrass, reed canarygrass or Oryza longistaminata.

Characterization and Phylogenetic Analysis of Magnaporthe spp. strains on VariousHosts in Iran

“…AFLP marker was also recognized here to be the most useful DNA fingerprinting tool for resolving the high genetic variation of this fungus compared with other fingerprinting techniques applied by several previous researchers such as RAPD and rep-PCR (6,15,(22)(23)(24). However, this research confirmed results obtained by JavanNikkhah (15) showing the low genetic variation among strains isolated from rice in Iran.…”

“…The low level of pathotype diversity (22) and lack of correlation between DNA fingerprint and pathotypes suggest that selection has favored the same spectrum of virulence in each clonal lineage. There was no evidence for sexual recombination in the studied population which is consistent with the dominant asexual reproduction observed in most rice-growing areas of the world.…”

Construction of overexpression vectors of Magnaporthe oryzae genes BAS1 and BAS4 fusion to mCherry and screening of overexpression strains

“…Magnaporthe oryzae (Ascomycotina) infection causes severe diseases in rice that affects yield, and can also infect many other gramineous plants (Kato et al, 2000;Couch and Kohn, 2002). Rice varieties that contain resistance genes can easily lose their resistance after years of consecutive large-scale cultivating, because the resistance is quickly circumvented by the emergence of virulent strains, which are caused by deletion of the Avr gene (Yoshida et al, 2009), expression modification (Kang et al, 2001;Fudal et al, 2007) and point mutation (Orbach et al, 2000).…”

Is the Fungus Magnaporthe Losing DNA Methylation?

“…Several genes involved in cytosine methylation have been identified in these organisms. Dim-2 in N. crassa (Kouzminova and Selker 2001) (Kato et al 2000; Couch and Kohn 2002). Interestingly, we previously found that the DNA methylation status of the long terminal repeat (LTR) retrotransposon, Magnaporthe gypsy-like element (MAGGY), differed among the M. oryzae subgroups.…”

“…Taxonomically, it belongs to the class Ascomycetes and family Sordariaceae, as does N. crassa. Magnaporthe isolates can be classified into several subgroups according to their host plants (Kato et al 2000;Couch and Kohn 2002). Interestingly, we previously found that the DNA methylation status of the long terminal repeat (LTR) retrotransposon, Magnaporthe gypsy-like element (MAGGY), differed among the M. oryzae subgroups.…”