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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.1986.tde-20220207-182321
Document
Author
Full name
Ana Paula Ayres Bordin
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1986
Supervisor
Title in Portuguese
Estudo da variabilidade genética e patogênica de Pyricularia spp. em arroz (Oryza sativa L.) e outras gramíneas
Keywords in Portuguese
ARROZ
BRUSONE
FUNGOS FITOPATOGÊNICOS
GRAMÍNEAS
PATOGENICIDADE
VARIAÇÃO GENÉTICA
Abstract in Portuguese
Objetivando estudar causas da variação patogênica do fungo Pyricularia oryzae Cav., oito isolados de Pyricularia spp. provenientes de gramíneas não cultivadas e cinco raças provenientes do arroz foram caracterizados sob o ponto de vista patológico, enzimático, morfológico e fisiológico. Os testes de patogenicidade utilizando hospedeiros diferenciais de arroz e outras gramíneas, evidenciaram patogenicidade das raças do fungo do arroz a algumas destas espécies de gramíneas, principalmente a Paspalum notatum um Flugge e a Paspalum paniculatum. Os isolados de Pennisetum setosum (Swartz) L. e Hyparrhenia rufa (Nees.) Stapf. foram patogênicos a algumas variedades de arroz. Também houve uma variação de padrões de reações das raças de arroz explicadas pelas condições diferentes de ambiente entre os três experimentos. A análise eletroforética de cinco sistemas enzimáticos (esterase, fosfatase ácida, malato desidrogenase, superóxido dismutase e leucina aminopeptidase) revelou padrões de bandas similares entre as raças de arroz e considerável diversidade entre os outros isolados, sugerindo a uniformidade genética entre fungos provenientes do mesmo hospedeiro (arroz) e diversidade genética entre isolados de outras espécies não cultivadas. Portanto, a variação da patogenicidade entre as raças de arroz não pode ser detectada através dos sistemas enzimáticos utilizados. Os isolados de P. setosum e H. rufa apresentaram os mesmos padrões de bandas que as raças isoladas do arroz. De uma maneira geral, as características morfológicas de colônia foram variáveis, sendo que os conídios de P. oryzae do arroz tinham tendência de serem mais alongados. Os isolados de P. setosum e H. rufa apresentaram morfologia de colônia e dos conídios semelhantes aos das raças de arroz. As células dos conídios eram uninucleadas. A análise da velocidade de crescimento em três meios de cultura (BDA, AVEIA e definido B) mostrou diferenças entre as raças de arroz e isolados de outras gramíneas. De acordo com a caracterização patogênica, enzimática, morfológica e fisiológica, sugere-se que os isolados de Pyricularia spp. obtidos de P. setosum e H. rufa sejam Pyricularia oryzae Cav. utilizando estas plantas como hospedeiros alternativos. Isto também pode explicar a ocorrência da doença em áreas onde esta ainda não havia sido constatada.
Title in English
Genetic and pathogenic variability of Pyricularia spp. on rice (Oryza sativa L.) and other gramineous
Abstract in English
The objective of the present work was to study the causes of pathogenic variation of the rice blast fungi, Pyricularia oryzae cav. Pathogenicity, morphology, physiological and enzymatical aspects of the fungus were studied. A total of thirteen isolates of Pyricularia spp. were used, eight from gramineous species and five from rice. Pathogenicity tests using a set of eighteen differential varieties of rice and eighteen gramineous species showed that Paspatum notatum Flügge and i>Paspatum paniculatum were the gramineous most affected. The isolates of Pennisetum setosum (Swartz) L. and Hyparrhenia rufa (Neis.) Stapf. Were pathogenic to some rice differential varieties. Also it was observed the variation of reaction of rice fungus races to the differentials varieties due to different micro-climatical conditions through the three experiments. Eletrophoretic analysis using five enzimatic systems (Esterase, Acid phosphatase, Dehidrogenase Malat, Dismutase Superoxid and Aminopeptidae Leucine) showed similar band patterns among rice fungus races and considerable diversity among gramineous isolates, suggesting the genetic uniformity among fungi from the same host (rice) and genetic diversity anong other isolates. So the variability on pathogenicity of the rice fungus races could not be detected by the enzimatic systans used. The isolates of P. setosum and H. rufa showed the same band patterns as those from rice. Generally, the morphological characteristics of colony and conidiospore were variable, and conidia of isolates from rice plants were longer than the others. All the conidiospore cells were uninucleate. Isolates of P. setosum and H. rufa showed similar morphological characteristics of colony andconidiospores to those of rice fungus races. The growth rate in three rnedium (PDA, Oat meal Agar and Defined B) was different among rice fungus races and those of other gramineous. According to pathogenical, enzimatical, morphological and physiological characterization, it was suggested that the isolates obtained from P. setosum and H. rufa were Pyricularia oryzae Cav. Also, it was suggested that this gramineous were considered as alternative hosts of rice blast fungus. This can explain the ocurrence of rice blast epidemies in regions where it is not common.
 
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2022-02-07
 
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