Distribution and characterization of isolates of Colletotrichum lindemuthianum in Brazil. / DistribuiÃÃo e caracterizaÃÃo de isolados de Colletotrichum lindemuthianum no Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Colletotrichum lindemuthianum, the causal agent of anthracnose, is responsible for expressive damages to the common bean crop. The high pathogenic variability is the main problem for effective and long-term control. The aim of this work were to study the distribution of isolates of C. lindemuthianum originating from different regions of Brazil and to verify if the largest variability of the pathogen it is due to differences among or within races, using differential cultivars and RAPD markers. Eighty-eight isolates from common bean from different producing regions in Brazil, except for the race 2047, obtained from Costa Rica. Initially a characterization was carry out based on the inoculation of differential cultivars. Fourteen RAPD primers and two PCR primers were used in the molecular analysis. The primers amplified a total of 64 polymorphic bands, with average of 4.4 polymorphic bands per primer. Pairwise similarities of Nei and Li were calculated and two dendrograms were generated. The Shannon diversity index was estimated for each sampled state. An analysis of molecular variance (AMOVA) was carried out, considering two hierarchization levels, states and races. The races 65, 81 and 73 were the most frequent, occurring in most of the common bean producing regions. The emergence of races 337 and 593 was verified. The genetic similarity among the isolates varied from 0.65 to 0.99, with average of 0.85. The descriptive analyses revealed a tendency of differentiation of races for origin areas. The Shannon diversity index revealed that the state of GoiÃs presents larger genetic diversity, possibly due to the presence of race 593, whereas the state of Rio Grande do Sul presents the smallest genetic diversity. There was no correlation between the geographical distances and genetic similarities obtained by RAPD markers. No correlation was observed between the RAPD markers and the characterization accomplished by inoculation with differential cultivars. AMOVA demonstrated that 92.45% of the variation was contained within states and 7.55% among states, showing the existence of a great exchange of genetic materials within states. At the race level most of the variation (80.85%) was observed within races.

ASSUNTO(S)

marcadores rapd feijÃo doenÃa fungica antracnose cultivares antracnoses variabilidade patogÃnica cultivars melhoramento vegetal common bean rapd markers fungi disease variabilidade genÃtica pathogenic variability genetics variability

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