Abstract
Brassica nigra plants showing symptoms caused by root-knot nematodes were detected in the municipality of La Joya, Arequipa Province, Peru. Based on morphology, esterase phenotypes, and species-specific characterized amplified region (SCAR) sequence, the causal agent was identified as Meloidogyne incognita. Pathogenicity was confirmed by a modified version of Koch’s postulates. To our knowledge, this is the first report of M. incognita infecting Brassica nigra in Peru.
Highlights
Koch is important as a crop plant; it may have contributed to the evolution of several species in the genus Brassica (El-Esawi, 2017)
In February 2020, many nematode galls (Fig. 1A, B) were observed on the roots of black mustard plants, and samples were taken from areas (16°27′43.5′′S; 71°49′19.6′′W), in La Joya, Arequipa Province, Peru
In order to identify the plant-parasitic nematode spe cies, a combination of morphological, biochemical, and molecular analyses were performed. This population of root-knot nematode was iden tified to species with esterase phenotypes (n = 36 females) (Carneiro and Almeida, 2001); morphology, and morphometrics of second-stage juveniles (J2) (n = 30), females (n = 10), and perineal patterns (n = 15); species molecular identification was con firmed by PCR species-specific characterized am plified region (SCAR) sequence for confirmation, using a primer set composed of inc-K14-F (5′-GG GATGTGTAAATGCTCCTG-3′) and inc-K14-R (5′-CCC GCTACACCCTCAACTTC-3′) (Randig et al, 2002)
Summary
Brassica nigra (L.) W.D.J. Koch (black mustard) is important as a crop plant; it may have contributed to the evolution of several species in the genus Brassica (El-Esawi, 2017). Among the plant-parasitic nematodes, the most important genus is Meloidogyne (Göldi, 1887), which causes damage in the form of root galls and may reduce in the number of roots, and predispose the plant to fungal and bacterial diseases causing losses in crop yields (Karssen, 2002; Sikora et al, 2018). In February 2020, many nematode galls (Fig. 1A, B) were observed on the roots of black mustard plants, and samples were taken from areas (16°27′43.5′′S; 71°49′19.6′′W), in La Joya, Arequipa Province, Peru.
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