Caracterização da variabilidade patogênica e interação diferencial de isolados de Curtobacterium flaccumfaciens pv. flaccumfaciens em feijoeiro-comum
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2013-03-27
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Universidade Federal de Goiás
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The common bean (Phaseolus vulgaris L.) is cultivated throughout the year in many regions of Brazil, in three different growing seasons, resulting in a estimated harvest (2012/2013) of 3,4 million tons. As a consequence of being cultivated in many ecosystems, this crop is exposed to many abiotic factors, accentuating losses and making it more susceptible to pathogens. Among the economically relevant diseases, the bacterial wilt, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens can cause production losses of up to 90%. The Curtobacterium flaccumfaciens pv. flaccumfaciens colonizes the xylematic vessels, blocking the transport of water and nutrients to the upper part of the plant and causing mosaic, flaccidity, wizen leaf board, wizen leaf burn, wilt and death. In Brazil, C. flaccumfaciens pv. flaccumfaciens was found for the first time in 1995, during the “rainy season” in the State of São Paulo. Currently, it is found in many other States, Parana, Santa Catarina, Goiás, Distrito Federal and Mato Grosso do Sul. For identifying C. flaccumfaciens pv. flaccumfaciens, morphological and biochemical methods were efficient, as well as the iniciators CffFOR2-CffREV4 were specific in PCR reaction for the 24 isolates. The preservation methods Castellani, filter paper and phosphate-glycerol buffer were efficient to maintain the viability of Cff isolates (Multifunctional Microorganisms Collection, Embrapa Arroz e Feijao) innoculated in Ouro Branco, BRS Esplendor and CNFP10132. According to the Scott & Knott test (1974), four groups of different aggressiveness were formed. Among these, eight isolates were chosen, two from each aggressivity group, for “race” identification, diferential interaction studies and identification of resistant genotypes. The innoculation of 30 genotypes of common bean enabled the identification of a differential interaction between the C. flaccumfaciens pv. flaccumfaciens isolates and the genotypes of the common bean. The genotypes IPA 9, Ouro Branco and Michelite were the most resistant ones, and the genotypes CNFRS 11997 and Frijólica 0-3-1 were the most susceptible ones. The isolates CNPAFCff25 and CNPAFCff 04 were the most aggressive ones, and the isolates CNPAFCff33 and CNPAFCff11 were the least aggressive ones. The methodology of partial diallel Melo & Santos (1999) allowed the classification of eight races and fifteen differential cultivars. After innoculation with the most aggressive isolate CNPAFCff 25 and the least aggressive isolate aggressive CNPAFCff 31, the analysis of scanning electron microscopy images revealed the formation of tangled structures resistance structures in genotypes Ouro Branco and IPA 9,
whereas no such structures were observed in the moderately resistant genotype Diacol Calima and the susceptible genotypes CNFRS 11997 and CNFC 10429. Employing the methodology of stability Wricke was possible to identify genotypes which contributed most to the interaction effects, so the genotypes indicated to compose the differential series. The methodology of Lin and Binns possible to analyze the behavior of genotypes demonstrating that they have followed the principles of gene-gene theory.
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LIMA, S. C. D.V. Caracterização da variabilidade patogênica e interação diferencial de isolados de Curtobacterium flaccumfaciens pv. flaccumfaciens em feijoeiro-comum. 2013. 98 f. Dissertação (Mestrado em Genética e Melhoramento de Plantas) - Universidade Federal de Goiás, Goiânia, 2013.