Post-infectional resistance in traditional leafy vegetable infected with root-knot nematodes

Abstract

Traditional leafy vegetables are increasingly being recognized as parents in plant breeding, and source of improved nutrition and food supply. Wild cucumber (Cucumis myriocarpus), a traditional leafy vegetable has been reported to possess some resistance to root-knot (Meloidogyne species) nematodes; however, the form of nematode resistance in these plants is not documented. The objective of this study was to determine the possible mechanism of nematode resistance in C. myriocarpus to M. incognita and M. javanica under greenhouse conditions. Two separate experiments of C. myriocarpus were each inoculated with second-stage juveniles (J2) of M. incognita or M. javanica. Harvesting of seedlings was conducted every other day from 2 days after inoculation. At each harvest, roots of five seedlings were stained using acid fuchsin method for assessment and number of necrotic spots, giant cells, rootlet interference, root galls and nematode juveniles counted. Harvest period had highly significant effects (P ≤ 0.01) on numbers of giant cells, rootlet interference and root galls, but were not significant on necrotic spot number in C. myriocarpus - M. javanica relations. Harvest interval were significant (P ≤ 0.05) on giant cell number and highly significant on root gall number in C. myriocarpus - M. incognita relations. The assessment of nematode infection showed that there was delayed penetration of both M. incognita and M. javanica in C. myriocarpus but their ability to cause disease was impaired. In conclusion, post-infectional resistance is the possible mechanism in C. myriocarpus traditional leafy vegetable against the two Meloidogyne species.