Estudo morfométrico comparativo de populações de Rotylenchulus reniformis (Nemata: Rotylenchulinae) do Brasil
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Data
2003-06-01
Autores
Soares, Pedro L. M. [UNESP]
Santos, Jaime M. dos [UNESP]
Lehman, Paul S.
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Fitopatologia
Resumo
Quarenta e oito populações de Rotylenchulus reniformis foram recuperadas de amostras de solo e raízes de diferentes culturas e inoculadas em diferentes plantas hospedeiras, mantidas em microparcelas no Departamento de Fitossanidade da UNESP/FCAV, Campus de Jaboticabal, São Paulo. Os sintomas da doença causada pelo nematóide em algodoeiro (Gossypium hirsutum), no campo, foram documentados, bem como o hábito de parasitismo do nematóide em raízes de algodão e de mamoeiro (Carica papaya), utilizando-se de coloração in situ do nematóide com fuccina ácida. Efetuou-se a comparação morfológica de todas as populações, ao microscópio óptico composto, em montagens temporárias e, de algumas, ao microscópio eletrônico de varredura. Para as observações ao microscópio eletrônico de varredura, fêmeas adultas presas às raízes foram fixadas em glutaraldeído e pós-fixadas em tetróxido de ósmio, desidratadas em álcool etílico, secas em secador de ponto crítico, montadas, recobertas com 35 nm de ouro, observadas e elétromicrografadas em 15 kV. Os dados obtidos confirmam que R. reniformis é a única espécie do gênero distribuída nos agroecossistemas brasileiros e que a amplitude de variação de caracteres morfométricos em populações brasileiras desse nematóide, tais como comprimento do estilete, V % e forma da cauda, é maior que em populações da mesma espécie de outras regiões do mundo. Foram ilustradas fêmeas jovens de R. reniformis com a cauda bifurcada, e esse detalhe da morfologia do nematóide ainda não havia sido relatado.
Forty-eight populations of Rotylenchulus reniformis were obtained from soil and root samples of different crops and inoculated into various host plants grown in microplots at the Departamento de Fitossanidade of the Universidade Estadual Paulista, Campus de Jaboticabal, São Paulo, Brazil. The symptoms of the disease caused by the nematode in cotton (Gossypium hirsutum) plants were documented in field and the parasitic behavior of the nematode in roots of cotton and papaya (Carica papaya) plants were investigated by in situ staining of the nematode with acid fuchsin. All populations were studied with light microscopy in temporary mounts and some were also examined using scanning electron microscopy (SEM). For SEM, mature females attached to roots were fixed in buffered glutaraldehyde and post-fixed in osmium tetroxide. The samples were then dehydrated in ethanol, dried in a critical point dessicator, mounted, coated with a 35-nm layer of gold, examined and electronmicrographed at 15 kV. The data confirm that R. reniformis is the only species of the genus distributed in Brazil and based on data from the literature, the variations of the morphometric characteristics among R. reniformis Brazilian populations, such as stylet length, V % and tail shape are greater than in populations of the same species from other parts of the world. Young females with bifurcated tails were documented in R. reniformis, a morphological feature that had not been previously reported.
Forty-eight populations of Rotylenchulus reniformis were obtained from soil and root samples of different crops and inoculated into various host plants grown in microplots at the Departamento de Fitossanidade of the Universidade Estadual Paulista, Campus de Jaboticabal, São Paulo, Brazil. The symptoms of the disease caused by the nematode in cotton (Gossypium hirsutum) plants were documented in field and the parasitic behavior of the nematode in roots of cotton and papaya (Carica papaya) plants were investigated by in situ staining of the nematode with acid fuchsin. All populations were studied with light microscopy in temporary mounts and some were also examined using scanning electron microscopy (SEM). For SEM, mature females attached to roots were fixed in buffered glutaraldehyde and post-fixed in osmium tetroxide. The samples were then dehydrated in ethanol, dried in a critical point dessicator, mounted, coated with a 35-nm layer of gold, examined and electronmicrographed at 15 kV. The data confirm that R. reniformis is the only species of the genus distributed in Brazil and based on data from the literature, the variations of the morphometric characteristics among R. reniformis Brazilian populations, such as stylet length, V % and tail shape are greater than in populations of the same species from other parts of the world. Young females with bifurcated tails were documented in R. reniformis, a morphological feature that had not been previously reported.
Descrição
Palavras-chave
Taxonomia, nematóide reniforme, Microscopia eletronica de varredura, Morfometria
Como citar
Fitopatologia Brasileira. Sociedade Brasileira de Fitopatologia, v. 28, n. 3, p. 292-297, 2003.