Activity of hydroxamic acids from Secale cereale against the plant-parasitic nematodes Meloidogyne incognita and Xiphinema americanum

• Published in: Phytopathology Vol. 95; no. 10; pp. 1116 - 1121
• Main Authors: Zasada, I.A, Meyer, S.L.F, Halbrendt, J.M, Rice, C
• Format: Journal Article
• Language: English
• Published: St. Paul, MN American Phytopathological Society 01.10.2005
• Subjects: Biological and medical sciences; chemical constituents of plants; dose response; Fundamental and applied biological sciences. Psychology; hydroxamic acids; Meloidogyne incognita; nematode control; Phytopathology. Animal pests. Plant and forest protection; plant extracts; plant parasitic nematodes; Secale cereale; toxic substances; Maryland; Monocotyledones; Plant pathology; Secale cereale; Microbiology; Plant pathogen; Metabolite; Toxicity; Xiphinema americanum; Cereal crop; Soils; Meloidogyne incognita; Gramineae; Angiospermae; Helmintha; Nemathelminthia; Spermatophyta; Invertebrata; Nematoda
• ISSN: 0031-949X; 1943-7684
• DOI: 10.1094/PHYTO-95-1116

Cyclic hydroxamic acids are secondary metabolites found in the family Poaceae and have been implicated in the allelopathy of rye (Secale cereale). The toxicity of these compounds against plant-parasitic nematodes is unknown. DIBOA (2,4-dihydroxy-(2H)-1,4-benzoxazin-3(4H)- one), DIMBOA (2,4-hydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)- one), and their degradation products BOA (benzoxazolin-2(3H)-one) and MBOA (6-methoxy-benzoxazolin-2(3H)-one) were screened in vitro against Meloidogyne incognita second-stage juveniles (J2) and eggs and mixed-stages of Xiphinema americanum. Xiphinema americanum was more sensitive to DIBOA and DIMBOA than M. incognita J2, with a maximum apparent mortality of 96 and 92% compared to 73 and 72% at 90 μg/ml. Eggs of M. incognita were less sensitive to the hydroxamic acids than J2; only DIBOA resulted in a 50% reduction in egg hatch, with a lethal concentration (LC50) of 74 μg/ml compared to 21 μg/ml for J2. When M. incognita J2 were exposed to DIBOA for 48 h and the compound was removed and replaced with water, the LC50 value increased from 21.0 to 40.7 μg/ml. MBOA was not toxic to X. americanum or M. incognita eggs, but was toxic to M. incognita J2, with LC50 values of 44 and 20 μg/ml before and after the compound was removed and replaced with water. BOA was the least toxic hydroxamic acid tested; it did not reduce M. incognita egg hatch after 1 week of exposure or increase X. americanum mortality after 24 h of exposure. While in vitro studies provide a valuable starting point in determining the toxicity of the chemical component of rye, the relevance of the data to soil remains to be determined.