Inferência filogenética revela a complexa etiologia das manchas areolada e foliar em seringueira e em outras espécies cultivadas na Amazônia
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Data
2010-09-01
Autores
Gaino, Ana Paula da Silva de Campos [UNESP]
Basseto, Marco Antonio [UNESP]
Gasparotto, Luadir
Poltronieri, Luiz Sebastião
Ceresini, Paulo Cezar [UNESP]
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Editor
Editora da Universidade Estadual de Maringá (EDUEM)
Resumo
A mancha areolada de Thanatephorus é uma das doenças mais importantes da seringueira (Hevea brasiliensis) na Amazônia brasileira. Além da seringueira, o fungo T. cucumeris (fase anamórfica Rhizoctonia solani) causa doenças foliares em outras espécies nativas ou cultivadas na região. Baseando-se na ausência de informações sobre quais os grupos de anastomose (AG) de R. solani estão associados à seringueira e a outros hospedeiros na Amazônia, testou-se a hipótese de que estes isolados pertencem a AG distintos. Também não há informação sobre a patogenicidade cruzada, à seringueira, de isolados provenientes de outros hospedeiros. A determinação do AG foi efetuada com base em análise filogenética da região ITS do rDNA. Concluiu-se que um novo subgrupo de R. solani (o AG-2-2 Hb) é o principal agente causal da mancha areolada em seringueira. Entretanto, isolados de outros AGs (AG-1 IB e ID, AG-4 HGI) e de Ceratobasidium sp. (Rhizoctonia sp. binucleada AG-R), oriundos de hospedeiros distintos, também infectam seringueira. Isto implica diversidade de fonte de inóculo para a sobrevivência e disseminação dos patógenos. de maneira inédita se relata a ocorrência de um novo AG de R. solani infectando citros no Acre, Brasil, distinto dos demais relatados no mundo (provavelmente AG-14).
Thanatephorus target spot is one of the most important diseases of the rubber tree (Hevea brasiliensis) in the Amazon region of Brazil. In addition to rubber tree, the fungus Thanatephorus cucumeris (anamorphase = Rhizoctonia solani) causes several foliar diseases on other agricultural crops or native species in the region. Based on the lack of information on which anastomosis groups (AG) of R. solani are associated with rubber tree and other hosts in the Amazon, we tested the hypothesis that these isolates belong to distinct AGs. There is no information about the cross pathogenicity (to rubber tree) of isolates from other hosts. The AG was determined based on phylogenetic analyses of the ITS region of the rDNA. We concluded that a new subgroup of R. solani (the AG-2-2 Hb) is the main pathogen causing the rubber tree leaf spot. However, isolates from other AGs (AG-1 IB and ID, AG-4 HGI) and from Ceratobasidium sp. (binucleate Rhizoctonia sp. AG-R) from distinct hosts can also infect the rubber tree. This implicates in diversity of inoculum sources for the survival and spread of the leaf spot pathogens. For the very first time, we report the occurrence of a new AG of R. solani infecting citrus in Acre, Brazil, which is distinct from all the others already described worldwide (probably AG-14).
Thanatephorus target spot is one of the most important diseases of the rubber tree (Hevea brasiliensis) in the Amazon region of Brazil. In addition to rubber tree, the fungus Thanatephorus cucumeris (anamorphase = Rhizoctonia solani) causes several foliar diseases on other agricultural crops or native species in the region. Based on the lack of information on which anastomosis groups (AG) of R. solani are associated with rubber tree and other hosts in the Amazon, we tested the hypothesis that these isolates belong to distinct AGs. There is no information about the cross pathogenicity (to rubber tree) of isolates from other hosts. The AG was determined based on phylogenetic analyses of the ITS region of the rDNA. We concluded that a new subgroup of R. solani (the AG-2-2 Hb) is the main pathogen causing the rubber tree leaf spot. However, isolates from other AGs (AG-1 IB and ID, AG-4 HGI) and from Ceratobasidium sp. (binucleate Rhizoctonia sp. AG-R) from distinct hosts can also infect the rubber tree. This implicates in diversity of inoculum sources for the survival and spread of the leaf spot pathogens. For the very first time, we report the occurrence of a new AG of R. solani infecting citrus in Acre, Brazil, which is distinct from all the others already described worldwide (probably AG-14).
Descrição
Palavras-chave
Rhizoctonia solani, grupamento de anastomose, patogenicidade cruzada, seringueira, citrus, Rhizoctonia solan, anastomosis grouping, cross pathogenicity, rubber tree, citrus
Como citar
Acta Scientiarum. Agronomy. Editora da Universidade Estadual de Maringá (UEM) - EDUEM, v. 32, n. 3, p. 385-395, 2010.