JOURNAL OF NEMATOLOGY Article | DOI: 10.21307/jofnem-2020-114 e2020-114 | Vol. 52 First report of southern root-knot , Meloidogyne incognita, infecting Brassica nigra in Peru

Jorge Airton Gómez-Chatata1, Juan José Tamo-Zegarra1, Teodocia Gloria Casa-Ruiz1 Abstract 1,2,3, and Cristiano Bellé * Brassica nigra plants showing symptoms caused by root-knot 1Universidad Nacional de San were detected in the municipality of La Joya, Arequipa Agustin de Arequipa, Arequipa, Province, Peru. Based on morphology, esterase phenotypes, and Peru. species-specific characterized amplified region (SCAR) sequence, the causal agent was identified as Meloidogyne incognita. Pathogenicity 2Universidade Federal de Santa was confirmed by a modified version of Koch’s postulates. To our Maria, Rio Grande do Sul, Santa knowledge, this is the first report ofM. incognita infecting Brassica Maria, Brazil. nigra in Peru. 3Instituto Phytus, Estação experimental de Itaara, Itaara, Keywords Rio Grande do Sul, Brazil. Black mustard, Detection, Diagnosis, Identification. *E-mail: [email protected] This paper was edited by Zafar Ahmad Handoo. Received for publication July 15, 2020.

Brassica nigra (L.) W.D.J. Koch (black mustard) is females) (Carneiro and Almeida, 2001); morphology, important as a crop plant; it may have contributed to and morphometrics of second-stage juveniles the evolution of several species in the genus Brassica (J2) (n = 30), females (n = 10), and perineal patterns (El-Esawi, 2017). It is widely cultivated, mostly (n = 15); species molecular identification was con­ continents as Australasia and the Americas (Rakow, firmed by PCR species-specific characterized ­am 2004). Black mustard was important oil seed crop, plified region (SCAR) sequence for confirmation, and has potential for use as green manure crops. using a primer set composed of inc-K14-F (5′-GG Plants attacked by pests, diseases, and plant- GATGTGTAAATGCTCCTG-3′) and inc-K14-R (5′-CCC parasitic nematodes can impair production both GCTACACCCTCAACTTC-3′) (Randig et al., 2002). qualitatively and quantitatively (Sikora et al., 2018). The nematode population density was 1,405 Among the plant-parasitic nematodes, the most J2/g of root. Morphometrics (means followed important genus is Meloidogyne (Göldi, 1887), which by ± standard deviation with the minimum and causes damage in the form of root galls and may maximum values in parentheses) of J2s: length reduce in the number of roots, and predispose the (L) = 360.7 ± 21.3 (310-476) μ m, a = 22.1 ± 4.3 (20.3- plant to fungal and bacterial diseases causing losses 25.5), c = 8.4 ± 0.5 (4.9-9.5), stylet length = 11.3 ± 0.5 in crop yields (Karssen, 2002; Sikora et al., 2018). (9.1-12.2) μ m, dorsal esophageal gland orifice to In February 2020, many nematode galls (Fig. 1A, B) base of stylet (DGO) = 2.5 ± 0.4 (1.7-2.6) μ m, tail were observed on the roots of black mustard plants, length = 39.5 ± 1.0 (39.0-48.5) μ m and hyaline tail and samples were taken from areas (16°27′43.5″S; terminus = 10.5 ± 0.5 (9.5-11.2) μ m. Morphometrics of 71°49′19.6″W), in La Joya, Arequipa Province, Peru. females: L = 655.5 ± 30.0 (550.4.5-700.5) μ m, stylet In order to identify the plant-parasitic nematode spe­ length = 14.5 ± 0.5 (12.1-15.4) μ m, and DGO = 3.5 ± 0.2 cies, a combination of morphological, biochemical, (2.8-4.0) μ m. The perineal pattern of the female and molecular analyses were performed. included a high and square dorsal arch with wavy This population of root-knot nematode was iden­ striae bending toward area the lateral lines and the tified to species with esterase phenotypes (n = 36 absence of distinct lateral line incisures. The overall

© 2020 Authors. This is an Open Access article licensed under the Creative 1 Commons CC BY 4.0 license, https://creativecommons.org/licenses/by/4.0/ First report of southern root-knot nematode, Meloidogyne incognita, infecting Brassica nigra in Peru: Gmez-Chatata et al.

Figure 1: A and B: Roots of Brassica nigra (L.) W.D.J. Koch showing galls induced by Meloidogyne incognita (Kofoid and White, 1919; Chitwood, 1949).

morphology and morphometrics of this population Additional surveys of black mustard may warrant the appears similar to that of Meloidoyne incognita development of adequate control strategies for root- (Kofoid and White, 1919; Chitwood, 1949; Hunt and knot nematode if this nematode is widespread. Handoo, 2009). The polymorphisms of the esterase bands by electrophoresis revealed the phenotype I2 (Rm = 1.05 and 1.10) typical of M. incognita (Carneiro et al., References 1996). The PCR amplification using SCAR sequence Boneti, J. I. and Ferraz, S. 1981. Modificação do produced a specific fragment of expected size método de Hussey & Barker para extração de ovos de (∼ 399 bp) for M. incognita (Randig et al., 2002). Meloidogyne exigua de raízes de cafeeiro. Fitopatologia In greenhouse tests, Brassica nigra plantlets Brasileira, 6:553. were maintained in pots with 2 liters sterilized soil. In Carneiro, R. M. D. G. and Almeida, M. R. A. 2001. total, six replicates were inoculated with 3,000 eggs Técnica de eletroforese usada no estudo de enzimas and J2s from the original population of M. incognita, dos nematoides de galhas para identificação de in addition to a non-inoculated control. Eggs and espécies. Nematologia Brasileira 25:555–60. J2 were extracted from infected roots using the Carneiro, R. M. D. G., Almeida, M. R. A. and 0.5% NaOCl (Hussey and Barker, 1973) method as Carneiro, R. G. 1996. Enzyme phenotypes of Brazilian modified by Boneti and Ferraz (1981). Plants were well populations of Meloidogyne spp. Fundamental & maintained under greenhouse conditions at 25 ± 3°C. Applied Nematology 3:555–60. After 60 days, the inoculated plants exhibited galled Chitwood, B. G. 1949. Root-knot nematodes – part I. A revision of the genus Meloidogyne Göldi, root systems similar to plants observed in the field, 18 87. Proceedings of the Helminthological Society of with a nematode reproduction factor (final population/ Washington 16:90–104. initial population) of 23.5. The non-inoculated plants El-Esawi, M. A. 2017. Genetic diversity and evolution did not exhibit any galls. The morphological and of Brassica genetic resources: from morphology to molecular characterization of this root-knot nematode novel genomic technologies – a review. Plant Genetic were identical to those of M. incognita. Resources 15:388–99. To our knowledge, this is the first report of Göldi, E. A. 1887. Relatório sôbre a molestia do M. incognita parasitizing Brassica nigra in Peru. This cafeiro na provincial da Rio de Janeiro. Archuivos do finding may be important to Peruvian agriculture, Museu Nacional do Rio de Janeiro 8:7–123. since this nematode may damage black mustard Hunt, D. J. and Handoo, Z. A. 2009. “, plants becoming an additional problem for this crop. identification and principal species”, In Perry, R. N.,

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Moens, M. and Starr, J. (Eds), Root-knot Nematodes, Rakow, G. 2004. “Species origin and economic impor- Wallingford: CABI Publishing, pp. 55–118. tance of Brassica”, In Pua, E. C. and Douglas, C. J. (Eds), Hussey, R. S. and Barker, K. R. 1973. A comparison Biotechnology in Agriculture and Forestry, Vol. 54 New of methods of collecting inocula of Meloidogyne spp., York, Berlin and Heidelberg: Springer-Verlag, pp. 3–11. including a new technique. Plant Disease Reporter Randig, O., Bongiovanni, M., Carneiro, R. M. and 57:1025–8. Castagnone-Sereno, P. 2002. Genetic diversity of root- Karssen, G. 2002. The Plant-Parasitic Nematode knot nematodes from Brazil and development of SCAR Genus Meloidogyne Goldi, 1892 () in Europe marker specific for the coffee damaging species. Brill, Leiden. Genome 45:862–70. Kofoid, C. A. and White, W. A. 1919. A new Sikora, R., Coyne, D., Hallmann, J. and Timper, P. nematode infection of man. Journal of the American 2018. Plant Parasitic Nematodes in Subtropical and Medical Association 72:567–69. Tropical Agriculture, Wallingford: CABI Publishing.

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