ABSTRACT
Phytonematodes are among the main pathogens of the common bean. In general, control practices that aim to control these pathogens have not been regularly adopted in Brazil. The objectives of the present study were to evaluate the occurrence of phytonematodes in dry bean fields in Paraná and São Paulo states and estimate the pathogenicity of Pratylenchus brachyurus to dry bean in glasshouse experiments. Root and soil were sampled for nematode extraction, identification and estimation of population density. Four glasshouse experiments with different initial population densities were carried out to evaluate the effect of P. brachyurus on the growth of dry bean plants. Six species of phytonematodes were detected, namely Helicotylenchus dihystera, P. brachyurus, Pratylenchus crenatus, Meloidogyne javanica, Meloidogyne incognita and Rotylenchulus sp. The spiral nematode H. dihystera was found in all samples and was the most abundant species in both states. The lesion nematode P. brachyurus was also frequent, reaching 94% in Paraná and 100% in São Paulo. The root-knot nematodes and Rotylenchulus sp. were reported only in São Paulo fields (45% and 18% frequency, respectively), and P. crenatus only in Paraná (12%). The most abundant nematode in the soil was H. dihystera, and in roots was P. crenatus. It was demonstrated that densities of 6.66 specimens of P. brachyurus per cm3 of soil provoke visible and measurable root decay. In conclusion, survey data showed low phytonematode densities and pathogenicity tests demonstrated that densities above 6.67 specimens of P. brachyurus per cm3 of soil cause damage to the dry bean roots.
Subject(s)
Fabaceae , Nematoda/pathogenicity , Tylenchoidea , Agricultural Pests , PhaseolusABSTRACT
ABSTRACT: This study aimed to evaluate the host status of soybean genotypes to Meloidogyne javanica (Est J3), Meloidogyne sp.0 (Est R0), and M. graminicola (Est VS1). In the first experiment, all tested genotypes (BMX Potência RR, BMX Valente RR, BMX Icone IPRO, PELBR10-6049 RR, and TECIRGA 6070 RR) were susceptible to M. javanica, with reproduction factor (RF) >1.0, and resistant to Meloidogyne sp.0 (0.01 > RF < 0.15), whereas in the second experiment, all genotypes (BRS 246 RR, PELBR11-6038 RR, PELBR11-6001 RR, PELBR10-6005 RR, BMX Apolo RR, PELBR11-6028 RR, PF11651, PF103251, PELBR11-6035 RR, PELBR10-6050 RR, PELBR11-6042 RR, PELBR10-6017 RR, PELBR11-6007 RR, PELBR10-6016 RR, and PELBR10-6049 RR) were resistant to M. graminicola (0.06 > RF < 0.43).
RESUMO: No presente estudo objetivou-se avaliar a reação de genótipos de soja a Meloidogyne javanica (Est J3), Meloidogyne sp.0 (Est R0) e M. graminicola (Est VS1). No primeiro experimento, todos os genótipos (BMX Potência RR, BMX Valente RR, BMX Icone IPRO, PELBR10-6049 RR, and TECIRGA 6070 RR) testados mostraram-se suscetíveis a M. javanica, com fator de reprodução (FR) >1.0, e resistentes a Meloidogyne sp.0 (0.01 > FR < 0.15), enquanto no segundo experimento, todos os genótipos (BRS 246 RR, PELBR11-6038 RR, PELBR11-6001 RR, PELBR10-6005 RR, BMX Apolo RR, PELBR11-6028 RR, PF11651, PF103251, PELBR11-6035 RR, PELBR10-6050 RR, PELBR11-6042 RR, PELBR10-6017 RR, PELBR11-6007 RR, PELBR10-6016 RR, and PELBR10-6049 RR) testados comportaram-se como resistentes a M. graminicola (0.06 > FR < 0.43).
ABSTRACT
Root-knot nematodes (RKN) are major crop pathogens worldwide. Trichoderma genus fungi are recognized biocontrol agents and a direct activity of Trichoderma atroviride (Ta) against the RKN Meloidogyne javanica (Mj), in terms of 42% reduction of number of galls (NG), 60% of number of egg masses and 90% of number of adult nematodes inside the roots, has been observed in tomato grown under greenhouse conditions. An in vivo split-root designed experiment served to demonstrate that Ta induces systemic resistance towards Mj, without the need for the organisms to be in direct contact, and significantly reduces NG (20%) and adult nematodes inside tomato roots (87%). The first generation (F1) of Ta-primed tomato plants inherited resistance to RKN; although, the induction of defenses occurred through different mechanisms, and in varying degrees, depending on the Ta-Mj interaction. Plant growth promotion induced by Ta was inherited without compromising the level of resistance to Mj, as the progeny of Ta-primed plants displayed increased size and resistance to Mj without fitness costs. Gene expression results from the defense inductions in the offspring of Ta-primed plants, suggested that an auxin-induced reactive oxygen species production promoted by Ta may act as a major defense strategy during plant growth.
Subject(s)
Disease Resistance , Plant Diseases/parasitology , Solanum lycopersicum/growth & development , Solanum lycopersicum/immunology , Trichoderma/growth & development , Tylenchoidea/immunology , Animals , Gene Expression Profiling , Indoleacetic Acids/metabolism , Solanum lycopersicum/parasitology , Plant Development , Plant Diseases/immunology , Plant Roots/parasitology , Reactive Oxygen Species/metabolismABSTRACT
ABSTRACT: Soybean is a commodity of great economic importance worldwide, particularly in Brazil, world’s second largest producer. Nematodes, especially those of the Meloidogyne genus, severely limit productivity. Identification of nematode species is important for effective soybean management. Here, 26 populations of root-knot nematode (Meloidogyne spp.) from 15 municipalities in the states of Bahia, Mato Grosso, Goias, and Minas Gerais were characterized based on the morphology of the female perineal region, esterase profile, and identification based on amplification of specific regions of the population genome. Among the Meloidogyne spp. populations obtained, M. incognita and M. javanica, were identified. No mixed populations were present in the samples. Diagnosis based on molecular analysis was shown to be reliable and the fastest for characterization of nematode populations compared to other methods analyzed.
RESUMO: A soja é uma commodity de grande importância econômica em todo mundo, especialmente no Brasil, segundo maior produtor mundial. Os nematoides, em especial os do gênero Meloidogyne, causam grandes limitações na produtividade. A identificação das espécies de nematoides é uma informação importante para o manejo adequado. Neste trabalho, 26 populações do nematoide das galhas (Meloidogyne spp.), provenientes de municípios do estado da Bahia, Mato Grosso, Goiás e de Minas Gerais, foram caracterizados com base na morfologia da região perineal das fêmeas de Meloidogyne spp., seu perfil de esterase e identificação baseada em amplificação de regiões específicas do genoma dessas populações. Entre as populações de Meloidogyne spp. obtidas, identificou-se M. incognita e M. javanica. Não houve presença de populações mistas nas amostras analisadas. O diagnóstico baseado em análise molecular se mostrou mais rápido e confiável comparado ás outras análises.
