Root-knot nematode ( Meloidogyne incognita ) infection alters vegetative growth and nitrogen uptake and distribution in grapevine

Root-knot nematodes (RKN, Meloidogyne spp.) manipulate host cell developmental processes to build specialized feeding structure from which the larvae enlist nutrients. Nitrogen (N) is one of the most important components of plant metabolites, and isotopic tracers make it possible for us to study the transportation of the nitrogen metabolites in the whole plant. In order to figure out vegetative and physiological responses caused by RKN infection in vine, pot experiment was performed in this paper. The results showed that RKN infection weakened vine vigor with decreased biomass and increased root-shoot ratio. Whereas, before bursting the galls exhibited a higher metabolic activity, in comparison with control root, the root dehydrogenase activities improved 85 % and 71 % in the galls and adjacent roots respectively. In addition, RKN infection didn’t significantly alter nitrogen content and distribution in various tissues, which might be due to feeding pressure or duration. 15N Root labeling results indicated that RKN infection enhanced Nitrogen derived from fertilizer (Ndff) and nitrogen utilization efficiency of the annual root. It suggested that RKN temporarily turned grape root into nitrogen sinks to meet their demand. Finally, the infected plant retained relatively few storage nutrients in the root and shoot after defoliation.