Host suitability of soybean and corn genotypes to the root lesion caused by nematode under natural infestation conditions

Hospedabilidade de genótipos de soja e de milho ao nematoide das lesões radiculares, sob condições naturais de infestação

Anderli Divina Ferreira Rios Mara Rúbia da Rocha Alan Soares Machado Kássia Aparecida Garcia Barbosa Ávila Renato Andrade Teixeira Leonardo de Castro Santos Lilian Rosana Silva Rabelo About the authors

ABSTRACT:

Among the nematode management strategies, genetic resistance is one of the most appropriate and desirable. However, resistant soybean and corn genotypes resistant to Pratylenchus brachyurus are not available up to the moment. The objective of this study was to evaluate the host suitability of 50 soybean and 38 corn genotypes to P. brachyurus under natural infestation. Soybean genotypes BRSGO Chapadões, BRSGO Paraíso, M-Soy 7211 RR, M-Soy 8008 RR, Emgopa 313 RR, M-Soy 8411, BRSGO Juliana RR, Emgopa 316 RR, BRSGO Luziânia RR and TMG 103 RR, and corn genotype Agromem 30A06 reduced the nematode population during the evaluation period.

Key words:
Glycine max; Zea mays; Pratylenchus brachyurus; resistance

RESUMO:

Dentre as estratégias de manejo de nematoides, a utilização de resistência é uma das alternativas mais apropriadas e desejáveis. No entanto, até o momento, não se dispõe de genótipos de soja e de milho reconhecidamente resistentes a Pratylenchus brachyurus. O objetivo deste trabalho foi avaliar a reação de 50 genótipos de soja e 38 de milho a P. brachyurus em áreas naturalmente infestadas. Os genótipos de soja BRSGO Chapadões, BRSGO Paraíso, M-Soy 7211 RR, M-Soy 8008 RR, Emgopa 313 RR, M-Soy 8411, BRSGO Juliana RR, Emgopa 316 RR, BRSGO Luziânia RR e TMG 103 RR e o de milho Agromem 30A06 reduziram a população do nematoide ao longo do período de avaliação.

Palavras-chave:
Glycine max; Zea mays; Pratylenchus brachyurus; resistência

Pratylenchus brachyurus is widespread in Brazil and there are reports of its occurrence in many crops (MACHADO et al., 2006MACHADO, A.C.Z. et al. Evaluation of cotton damages caused by Pratylenchus brachyurus. Fitopatologia Brasileira, v.31, n.1, p.11-16, 2006. Available from: <Available from: http://www.scielo.br/pdf/fb/v31n1/a02v31n1.pdf >. Accessed: Jan. 25, 2014. doi: 10.1590/S0100-41582006000100002
http://www.scielo.br/pdf/fb/v31n1/a02v31...
; ALVES et al., 2011ALVES, T.C.U. et al. Host status of soybean cultivars to lesion nematode Pratylenchus brachyurus. Revista Biodiversidade, v.10, n.1, p.73-79, 2011. Available from: <Available from: http://periodicoscientificos.ufmt.br/index.php/biodiversidade/article/view/538/459 >. Accessed: Jan. 10, 2014.
http://periodicoscientificos.ufmt.br/ind...
; INOMOTO, 2011INOMOTO, M.M. Resistance evaluation of 12 maize hybrids to Pratylenchus brachyurus. Tropical Plant Pathology, v.36, n. 5, p.308-312, 2011. Available from: <Available from: http://www.scielo.br/pdf/tpp/v36n5/v36n5a06.pdf >. Accessed: Jan. 18, 2015. doi: 10.1590/S1982-56762011000500006
http://www.scielo.br/pdf/tpp/v36n5/v36n5...
). In soybean, its importance has increased in recent years, especially in the Midwest region, in areas of maize second crop after soybean in no tillage production systems under irrigation and in sandy soils (GOULART, 2008GOULART, A.M.C. Aspectos gerais sobre nematoides das lesões radiculares (gênero Pratylenchus). Embrapa Cerrados, 2008. 30p. (Documentos - ISSN 1517-5111; 219).). Corn is highly susceptible to nematodes, especially P. brachyurus (LORDELLO et al., 1985LORDELLO, R.A. et al. Reação de genótipos de milho a Pratylenchus spp. em campo. Nematologia Brasileira, v.9, n. 1, p.163-173, 1985.; INOMOTO, 2011INOMOTO, M.M. Resistance evaluation of 12 maize hybrids to Pratylenchus brachyurus. Tropical Plant Pathology, v.36, n. 5, p.308-312, 2011. Available from: <Available from: http://www.scielo.br/pdf/tpp/v36n5/v36n5a06.pdf >. Accessed: Jan. 18, 2015. doi: 10.1590/S1982-56762011000500006
http://www.scielo.br/pdf/tpp/v36n5/v36n5...
).

Among the main measures to control nematodes, the use of genetic resistance stands out. Although some preliminary research results regarding the reaction of soybean and corn genotypes to this nematode exist, data are not conclusive (ALVES et al., 2011ALVES, T.C.U. et al. Host status of soybean cultivars to lesion nematode Pratylenchus brachyurus. Revista Biodiversidade, v.10, n.1, p.73-79, 2011. Available from: <Available from: http://periodicoscientificos.ufmt.br/index.php/biodiversidade/article/view/538/459 >. Accessed: Jan. 10, 2014.
http://periodicoscientificos.ufmt.br/ind...
; INOMOTO, 2011INOMOTO, M.M. Resistance evaluation of 12 maize hybrids to Pratylenchus brachyurus. Tropical Plant Pathology, v.36, n. 5, p.308-312, 2011. Available from: <Available from: http://www.scielo.br/pdf/tpp/v36n5/v36n5a06.pdf >. Accessed: Jan. 18, 2015. doi: 10.1590/S1982-56762011000500006
http://www.scielo.br/pdf/tpp/v36n5/v36n5...
). Studies have been conducted under greenhouse and in field conditions in different locations in Brazil; however, few advances have been achieved, and, in some cases, with contradictory results. This can be attributed to different methods of evaluation and to the variability of the nematode present in different regions. For MACHADO et al. (2006MACHADO, A.C.Z. et al. Evaluation of cotton damages caused by Pratylenchus brachyurus. Fitopatologia Brasileira, v.31, n.1, p.11-16, 2006. Available from: <Available from: http://www.scielo.br/pdf/fb/v31n1/a02v31n1.pdf >. Accessed: Jan. 25, 2014. doi: 10.1590/S0100-41582006000100002
http://www.scielo.br/pdf/fb/v31n1/a02v31...
) variability occurs in nematode populations leading to differences in the aggressiveness of P. brachyurus. The fact that the interaction of P. brachyurus with plants does not induce specialized feeding cell formation makes it difficult to find resistance and to elucidate the mechanisms involved (GOULART, 2008GOULART, A.M.C. Aspectos gerais sobre nematoides das lesões radiculares (gênero Pratylenchus). Embrapa Cerrados, 2008. 30p. (Documentos - ISSN 1517-5111; 219).).

In order to evaluate commercial soybean and corn genotypes looking for resistance to P. brachyurus two trials were carried out: one with soybeans in Vicentinópolis/GO and the other with corn in Edéia/GO. Both experiments were installed in commercial crops under conventional sowing systems naturally infested by the nematode, with a history of high nematode populations and the occurrence of stunted spots in the previous harvest. The experimental design was a randomized complete block with split plot over time, with 50 treatments (genotypes) and eight replications for soybean and 38 treatments (genotypes) and ten replications for corn. The evaluations were performed at 30 and 60 days after emergence (DAE). Each plot consisted of a 50cm row, allowing a ten seed condensed sowing. Each row contained all genotypes ordered at random, composing a block.

For each evaluation, samplings were drawn collecting three plants from each plot. The shoots were discarded and the root systems taken to the laboratory for nematode extraction according to methodology described by COOLEN & D'HERD (1972COOLEN, W.A.; D'HERDE, C.J. A method for the quantitative extraction of nematodes from plant tissue. State of Nematology and Entomology Research Station, 1972. 77p.). Nematode density data were subjected to tests for normality and homogeneity of variance. Once the statistic assumptions were complied, the analysis of variance was performed with the Scott-Knott test at the 5% level of significance. Statistical tests were performed with data transformed into y'= y0.20 for soybean and y' = y0.057 for corn, according to BOX-COX (1964BOX, G.E.P.; COX, D.R. An analysis of transformations. Journal of the Royal Statistical Society. Series B (Statistical Methodological), v.26, n.2, p.211-252, 1964.) and subjected to the analysis of variance, using SAS statistical software (1999)STATISTICAL ANALYSIS SYSTEM - SAS. User's guide: statistic. 6.ed. Cary, 1999. 956p..

The mean test (P≤0.05) separated the soybean genotypes into two groups in both evaluations (Table 1). The analysis showed interaction between genotypes and evaluation periods (P≤0.05) for 12 soybean genotypes; ten with population reduction (BRSGO Chapadões, BRSGO Paraiso, M-Soy 7211 RR, M-Soy 8008 RR, Emgopa 313 RR, M-Soy 8411, BRSGO Juliana RR, Emgopa 316, BRSGO Luziania RR and TMG 103 RR), ranging from 46% to 70%. A possible explanation for the decline observed in the nematode population in the second evaluation is that the tested soybean cultivars have determined growth habit that paralyzes their growth after flowering, before entering the reproductive stage (NOGUEIRA et al., 2009NOGUEIRA, A. P. O. et al. Morfologia, Crescimento e Desenvolvimento. In: SEDIYAMA, T. Tecnologias de produção e usos da soja. Londrina: Mecenas, 2009. 314p. cap.1, p.7 - 16.). As roots stop growing, there is greater competition for food among nematodes, forcing their output from the plant or reducing their multiplication.

Other authors also tested some soybean genotypes tested in this study and, in some cases, results were confirmed. ALVES et al. (2011ALVES, T.C.U. et al. Host status of soybean cultivars to lesion nematode Pratylenchus brachyurus. Revista Biodiversidade, v.10, n.1, p.73-79, 2011. Available from: <Available from: http://periodicoscientificos.ufmt.br/index.php/biodiversidade/article/view/538/459 >. Accessed: Jan. 10, 2014.
http://periodicoscientificos.ufmt.br/ind...
) also observed that cultivars 'Emgopa 313 RR' and 'M-Soy 8411', considered potentially resistant in this study, had low reproduction factor (RF) under controlled conditions. RIBEIRO et al. (2007RIBEIRO, N.R. et al. Avaliação da reação de espécies vegetais ao nematoide das lesões radiculares. In: REUNIÃO DE PESQUISA DA SOJA DA REGIÃO CENTRAL DO BRASIL, 29., 2007, Campo Grande, MS. Resumos... Londrina: Embrapa Soja/ Uniderp, 2007, v.1, p.62-63. ) and MACHADO (2009MACHADO, A.C.Z. Host status of some selected Brazilian soybean cultivars to Pratylenchus brachyurus.In: INTERNATIONAL CONGRESS OF TROPICAL NEMATOLOGY, 2., 2009, Maceió, Al. Resumos... Maceió: Brazilian Nematological Society (BNS) and Organization of Nematologists of Tropical America (ONTA). 2009. V. 1, p.76. ) also found similar results for cultivar BRSGO Chapadões under greenhouse conditions. Conversely, 'TMG 103 RR' and 'BRSGO Paraiso' cultivars, which in the present study were considered resistant, presented high RF in a study by RIBEIRO et al. (2007RIBEIRO, N.R. et al. Avaliação da reação de espécies vegetais ao nematoide das lesões radiculares. In: REUNIÃO DE PESQUISA DA SOJA DA REGIÃO CENTRAL DO BRASIL, 29., 2007, Campo Grande, MS. Resumos... Londrina: Embrapa Soja/ Uniderp, 2007, v.1, p.62-63. ).

The corm genotypes tested were divided by the mean test (P≤0.05) in three groups, in both evaluations (30 DAE and 60 DAE) (Table 2). From the corn genotypes tested, 16 significantly increased the nematode population density at 60 DAE, most with an increase of over 100%. Similar results were found by LORDELLO et al. (1985LORDELLO, R.A. et al. Reação de genótipos de milho a Pratylenchus spp. em campo. Nematologia Brasileira, v.9, n. 1, p.163-173, 1985.), who also observed a gradual increase of nematodes P. brachyurus and P. zeae during the testing period in a trial in field with evaluations at 39, 59 and 90 DAS. INOMOTO (2011INOMOTO, M.M. Resistance evaluation of 12 maize hybrids to Pratylenchus brachyurus. Tropical Plant Pathology, v.36, n. 5, p.308-312, 2011. Available from: <Available from: http://www.scielo.br/pdf/tpp/v36n5/v36n5a06.pdf >. Accessed: Jan. 18, 2015. doi: 10.1590/S1982-56762011000500006
http://www.scielo.br/pdf/tpp/v36n5/v36n5...
) studied the reaction of corn hybrids to P. brachyurus under controlled conditions and observed RF ranging from 4.0 to 15.4.

In this study, only four corn genotypes showed low population density in both evaluations, which can indicate genetic resistance (Table 2). They were P 30F80, GNZ 2500, DKB 350 and NK Impacto. Hybrid Agromem 30A06, despite being among those that showed high population densities in the first evaluation, was the one that had the density reduced by 58% at 60 DAE.

Diverse results reported in different studies for soybean and corn genotypes may be due to differences in the methods used for conducting and evaluating experiments. Extraction and counting of nematodes from roots may still be the most appropriate method to check nematode population density as well as to evaluate crop yield related to the existence of tolerance to P. brachyurus under naturally infested field conditions. It is possible that the genotypes that remained with low nematode population density along the evaluation period may present mechanisms to make difficult the nematode penetration. Conversely, genotypes that presented significant reduction on the nematode population at the second evaluation may have some mechanism that works after the nematode has entered the roots. This suggests that new studies should look for mechanical or biochemical modifications in the plants due to the nematode parasitism.

Another hypothesis to explain the diversity of results when compared to other studies, is that there may be differences of aggressiveness among nematode populations of P. brachyurus from different regions of Brazil (FALLAS et al., 1996FALLAS, G.A. et al. Molecular and biochemical diversity among isolates of Radopholus spp. from different areas of the world. Jounal of Nematology, v.28, n.4, p.422-430, 1996. Available from: <Available from: http://journals.fcla.edu/jon/article/view/66835/64503 >. Accessed: Jan. 5, 2015.
http://journals.fcla.edu/jon/article/vie...
; MACHADO et al., 2006MACHADO, A.C.Z. et al. Evaluation of cotton damages caused by Pratylenchus brachyurus. Fitopatologia Brasileira, v.31, n.1, p.11-16, 2006. Available from: <Available from: http://www.scielo.br/pdf/fb/v31n1/a02v31n1.pdf >. Accessed: Jan. 25, 2014. doi: 10.1590/S0100-41582006000100002
http://www.scielo.br/pdf/fb/v31n1/a02v31...
), suggesting that studies to characterize the behavior of soybean and corn genotypes to this nematode should be sustained.

The genotypes of soybean and corn that remained with the lowest population densities in the two evaluation periods or significantly reduced the population in the second evaluation can be considered moderately resistant and be good choices for sowing in areas infested by the nematode. They can also be targeted for further investigations identifying genetic resistance.

REFERENCES:

  • ALVES, T.C.U. et al. Host status of soybean cultivars to lesion nematode Pratylenchus brachyurus. Revista Biodiversidade, v.10, n.1, p.73-79, 2011. Available from: <Available from: http://periodicoscientificos.ufmt.br/index.php/biodiversidade/article/view/538/459 >. Accessed: Jan. 10, 2014.
    » http://periodicoscientificos.ufmt.br/index.php/biodiversidade/article/view/538/459
  • BOX, G.E.P.; COX, D.R. An analysis of transformations. Journal of the Royal Statistical Society. Series B (Statistical Methodological), v.26, n.2, p.211-252, 1964.
  • COOLEN, W.A.; D'HERDE, C.J. A method for the quantitative extraction of nematodes from plant tissue. State of Nematology and Entomology Research Station, 1972. 77p.
  • FALLAS, G.A. et al. Molecular and biochemical diversity among isolates of Radopholus spp. from different areas of the world. Jounal of Nematology, v.28, n.4, p.422-430, 1996. Available from: <Available from: http://journals.fcla.edu/jon/article/view/66835/64503 >. Accessed: Jan. 5, 2015.
    » http://journals.fcla.edu/jon/article/view/66835/64503
  • GOULART, A.M.C. Aspectos gerais sobre nematoides das lesões radiculares (gênero Pratylenchus). Embrapa Cerrados, 2008. 30p. (Documentos - ISSN 1517-5111; 219).
  • INOMOTO, M.M. Resistance evaluation of 12 maize hybrids to Pratylenchus brachyurus. Tropical Plant Pathology, v.36, n. 5, p.308-312, 2011. Available from: <Available from: http://www.scielo.br/pdf/tpp/v36n5/v36n5a06.pdf >. Accessed: Jan. 18, 2015. doi: 10.1590/S1982-56762011000500006
    » https://doi.org/10.1590/S1982-56762011000500006» http://www.scielo.br/pdf/tpp/v36n5/v36n5a06.pdf
  • LORDELLO, R.A. et al. Reação de genótipos de milho a Pratylenchus spp. em campo. Nematologia Brasileira, v.9, n. 1, p.163-173, 1985.
  • MACHADO, A.C.Z. et al. Evaluation of cotton damages caused by Pratylenchus brachyurus. Fitopatologia Brasileira, v.31, n.1, p.11-16, 2006. Available from: <Available from: http://www.scielo.br/pdf/fb/v31n1/a02v31n1.pdf >. Accessed: Jan. 25, 2014. doi: 10.1590/S0100-41582006000100002
    » https://doi.org/10.1590/S0100-41582006000100002» http://www.scielo.br/pdf/fb/v31n1/a02v31n1.pdf
  • MACHADO, A.C.Z. Host status of some selected Brazilian soybean cultivars to Pratylenchus brachyurus.In: INTERNATIONAL CONGRESS OF TROPICAL NEMATOLOGY, 2., 2009, Maceió, Al. Resumos... Maceió: Brazilian Nematological Society (BNS) and Organization of Nematologists of Tropical America (ONTA). 2009. V. 1, p.76.
  • NOGUEIRA, A. P. O. et al. Morfologia, Crescimento e Desenvolvimento. In: SEDIYAMA, T. Tecnologias de produção e usos da soja. Londrina: Mecenas, 2009. 314p. cap.1, p.7 - 16.
  • RIBEIRO, N.R. et al. Avaliação da reação de espécies vegetais ao nematoide das lesões radiculares. In: REUNIÃO DE PESQUISA DA SOJA DA REGIÃO CENTRAL DO BRASIL, 29., 2007, Campo Grande, MS. Resumos... Londrina: Embrapa Soja/ Uniderp, 2007, v.1, p.62-63.
  • STATISTICAL ANALYSIS SYSTEM - SAS. User's guide: statistic. 6.ed. Cary, 1999. 956p.

  • 1
    CR-2015-0307.R1

Publication Dates

  • Publication in this collection
    Apr 2016

History

  • Received
    03 Mar 2015
  • Accepted
    13 Oct 2015
  • Reviewed
    15 Dec 2015
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