Evolutionary history of Phakopsora pachyrhizi in Brazil bases in nucleotide sequences of internal transcribed spacer region of nuclear ribossomal DNA / História evolutiva de Phakopsora pachyrhizi no Brasil com base em seqüências de nucleotídeos da região espaçadora interna do DNA ribossomal nuclear

AUTOR(ES)

Maíra Cristina Menezes Freire

DATA DE PUBLICAÇÃO

2007

RESUMO

The soybean is attacked by many pathogens, spite of all the diseases the Asiatic rust caused by the fungus Phakopsora pachyrhizi has been considered one of the most important pathogens. The symptoms are characterized for small points darker than the healthy tissue, where it is observed a bulge, which it opens in small pore expelling some uredionospores. Hardly infected plants show premature fallen leave, compromising then the formation and filling of some string beans and also the final weight of some grains. The most effective controlling method is the use of some resistant varieties, however the pathogenic large variability has bothered the research of these resistant varieties. This research has aimed search the special and temporal distribution of the genetic diversity of the Phakopsora pachyrhizi, and infer about the developed relations between some Brazilian, African and Asiatic isolates. Uredionospores were collected in 20 Brazilian places and also in South African. The genomic DNA was extracted from and amplified with the PCR using specifics primers for the ITS region of the nuclear genome in the Phakopsora pachyrhizi. The ITS1 and ITS2 regions were cloned and sequenced of independent forms. Four clones of each ITS regions in samples were sequenced, aimed to verify whether it might have variability of the pathogens in same location. The sequences were lined up and compared each others and also with isolates sequences of the Phakopsora pachyrhizi from different countries in GenBank. Later, the TCS program was used to obtain haplotypes net, one for the ITS1 sequences and other for the ITS2 region. The program ARLEQUIN was used to conduct the analysis of molecular variables, calculating the diversities between and in located samples, and also to calculate the genetic and nucleotide diversity. The net based on the ITS1 sequences, was able to distinguish 21 haplotypes between 96 sequences, while the net based on ITS2 distinguished 17 haplotypes between 86 sequences, showing that spite of Phakopsora pachyrhizi was recently inserted in Brazil, the Brazilian isolates show a great genetic variability. This net shows that distributed haplotypes in Brazil were also found in Africa and Asia, showing an ancestors relation. Comparing the sequences, it was observed the presence of at least three haplotypes for each location, showing a large genetic diversity among the locations, and it was proved by variability molecular analysis. The results support the hypothesis that the origin of this fungus in Brazil has been brought through spores, probably by area transportation through the Atlantic Ocean from Africa and this migration happen more than once.

ASSUNTO(S)

phakopsora pachyrhizi ferrugem da soja genetica molecular e de microorganismos filogeografia phakopsora pachyrhizi soybean rust

Documentos Relacionados

• Evolutionary history of Phakopsora pachyrhizi (the Asian soybean rust) in Brazil based on nucleotide sequences of the internal transcribed spacer region of the nuclear ribosomal DNA
• Polymorphic Internal Transcribed Spacer Region 1 DNA Sequences Identify Medically Important Yeasts
• Phylogenetic Classification of Trichophyton mentagrophytes Complex Strains Based on DNA Sequences of Nuclear Ribosomal Internal Transcribed Spacer 1 Regions
• Phylogenetic Classification of Trichophyton mentagrophytes Complex Strains Based on DNA Sequences of Nuclear Ribosomal Internal Transcribed Spacer 1 Regions
• Phylogenetic Classification and Species Identification of Dermatophyte Strains Based on DNA Sequences of Nuclear Ribosomal Internal Transcribed Spacer 1 Regions