Reaction of soybean cultivars to the root-knot nematode Meloidogyne javanica

Abstract

Meloidogyne javanica is one of the main nematodes that attack soybean crops and although genetic resistance is the ideal control measure, few cultivars are described as resistant among the innumerous cultivars recommended for the Central Region of Brazil. In this context, we aimed to evaluate the reaction of 29 soybean cultivars to M. javanica. Two experiments were conducted under greenhouse conditions in a completely randomized design with six replications. The plants were inoculated with a suspension of 2000 eggs and J2 of M. javanica and the evaluations occurred sixty days after the inoculation (DAI), determining the nematode population density and the reproduction factor. Based on the results from these two experiments we conducted another experiment selecting four soybean cultivars, one moderately resistant and three with an unknown behavior. These cultivars were inoculated with different concentrations of M. javanica inoculum. The experiment was conducted in a completely randomized design in a 4 x 4 factorial scheme with twelve replications. Evaluations were carried out at 10 DAI by observing the number of J2 and J3/ root system. At 45 DAI the nematode population density in the roots was evaluated. Of the soybean cultivars tested, none behaved as resistant. However, the cultivars UFU Carajás and BRSGO Paraíso presented less M. javanica development in the roots compared to the P98Y70 and NS 7478 and as the inoculum pressure was increased, the penetration and development of the nematode in the roots increased.Additional keywords: inoculum concentration; penetration; resistance; root-knot nematodes. ResumoMeloidogyne javanica é um dos principais nematoides que atacam a cultura da soja e, embora a resistência genética seja a medida de controle ideal, existem poucas cultivares descritas como resistentes dentre as inúme-ras cultivares recomendadas para a Região Central do Brasil. Neste contexto, objetivou-se avaliar a reação de 29 cultivares de soja ao nematoide M. javanica. Foram conduzidos dois experimentos em condições de casa de vegetação, instalados em delineamento inteiramente casualizado, com seis repetições. As plantas foram inoculadas com uma suspensão de 2.000 ovos e J2 de M. javanica, e as avaliações ocorreram sessenta dias após a inoculação (DAI), determinando-se a densidade populacional do nematoide e o fator de reprodução. A partir dos resultados destes experimentos, foram selecionadas quatro cultivares de soja, sendo uma moderadamente resistente e três com comportamento desconhecido, e foram inoculadas com diferentes concentrações de inó-culo de M. javanica. Este experimento foi conduzido em delineamento inteiramente casualizado, em esquema fatorial 4 x 4, com doze repetições. Avaliações foram realizadas aos 10 DAI, observando-se o número de J2 e J3/sistema radicular. Aos 45 DAI, avaliou-se a densidade populacional do nematoide nas raízes. Entre as cultivares de soja testadas, nenhuma se comportou como resistente. Porém as cultivares UFU Carajás e BRSGO Paraíso apresentaram menor desenvolv...

The host status of glyphosate-tolerant soybean genotypes to Meloidogyne incognita and Pratylenchus infection

“…Although 21 genotypes had Rfs < 1 in the 1st experiment, none of them except PRF-GCI7 and DM 6.2i RR could maintain the resistance trait (Rf < 1) under the higher temperature regime of the 2nd experiment. The present results hence coincide with those of Teixeira et al (2017) who showed that only the M. javanica resistance trait could be verified for two of the 14 soybean genotypes that were classified as resistant in an initial glasshouse experiment.…”

“…This is not unexpected since such anomalies have been reported from other studies for M. incognita-and/or M. javanica-resistant genotypes (Fourie et al 2006;Sharma et al 2006). Also, the Brazilian 'BRSGO Raissa' was classified as susceptible to M. javanica (Embrapa 2011), while Teixeira et al (2017) reported it as resistant. Such contrasting results may be due to the occurrence of different races or pathotypes or virulent populations of the target root-knot nematode species, as well as abiotic or biotic factors that occur in different climatic zones (Hussey and Janssen 2002) where soybean is grown.…”

South Africa: An Important Soybean Producer in Sub-Saharan Africa and the Quest for Managing Nematode Pests of the Crop

“…An early study also identified three soybean cultivars, Centennial, Forrest, and Hartwig, that were resistant against both the soybean cyst nematode (race 3) and M. incognita (race 3) [109]. Out of 29 soybean cultivars tested in Brazil for their resistance against M. javanica, none were found to be resistant, with only two (TMG 1288 RR and NS 8270) having moderate levels of resistance [110]. In Pakistan, local soybean varieties/lines viz.…”

Genome-Wide Association Study for Resistance to the <em>Meloidogyne javanica</em> Causing Root-Knot Nematode in Soybean

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