Gramíneas forrageiras como potenciais hospedeiros alternativos para o fitoplasma do enfezamento vermelho do milho / Grasses as potential alternative hosts for the maize bushy stunt phytoplasma

AUTOR(ES)

Isolda Cristina Ruschel Haas

DATA DE PUBLICAÇÃO

2006

RESUMO

Maize bushy stunt, caused by a phytoplasma, was reported in Brazil in the beginning of the seventies, and it was considered as not important for corn. Since the middle of the eighties decade, when the later planting practice and irrigation were adopted, the disease became relevant. Currently, maize bushy stunt represents one of the most important diseases and has caused significant losses. In some conditions the disease can limit the production, especially in relation to the region, used hybrids and crop season. A critical point to disease control is the lack of about survival of pathogen and vector, during the absence of corn crop on the field. This kind of information can be useful to promote the reduction of the initial inoculum, aiming a more efficient disease control. Thus, the objective of the present study was to evaluate some grasses and weeds species as potential alternative hosts of the maize bushy stunt phytoplasma and its vector Dalbulus maidis. Thirteen botanical species were experimentally inoculated with the phytoplasma by using infective leafhoppers. Evaluations were based upon symptom observation, molecular detection of the phytoplasma in tissue of inoculated plants and the of number of insects present in the plants. Detection was conducted by nested PCR and phytoplasma identification by RFLP analyses, using AluI, RsaI, KpnI and MboI as restriction enzymes. Phytoplasma was detected in three species, Panicum maximum, Brachiaria plantaginea and Brachiaria decumbens based on amplification of 16S rDNA, visualized as specific band in agarose gel. Insects remain on alive on the plants belonging to those three species up to the end of the assays. Thus, the present study showed the possibility of those species as potential alternative hosts to the pathogen and its vector, under natural conditions. The results can contribute for new investigations, in order to understanding the epidemiology of the disease, especially in relation to phytoplasma and vector survival.

ASSUNTO(S)

host plants fitoplasma interação planta-patógeno-vetor dalbulus maidis maize bushy stunt phytoplasma planta daninha enfezamento vermelho gramínea forrageira milho cigarrinha-vetora-de-doença

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