Nicotinamide adenine dinucleotide induced resistance against root-knot nematode Meloidogyne hapla is based on increased tomato basal defense

Abstract

Root-knot nematodes (RKN; Meloidogyne spp.) are among the most damaging pests to tomato production in the USA and worldwide, with yield losses ranging from 25 to 100%. Host resistance conferred by the Mi gene in tomato is effective against some species of RKN (e.g. M. incognita, M. javanica, and M. arenaria); however, there are virulent species and lines including M. hapla and M. eterolobii that break Mimediated resistance. Plant innate immunity is another possible form of defense against pathogen attack and is known to be induced by chemical elicitors. Nicotinamide adenine dinucleotide (NAD) is one such chemical elicitor that regulates plant defense responses to multiple biotic stresses. In this study, we investigated the role of NAD in the context of induced tomato innate immunity and RKN pathogenicity in two tomato cultivars; VFN and Rutgers, with and without Mi, respectively. Single soil drench application of NAD 24 hr before nematode inoculation significantly induced defense response pathways, reduced infective-juveniles penetration, number of galls, and increased plant mass in both cultivars. Importantly, we observed no direct toxic effects of NAD on nematode viability and infectivity. The results presented here suggest that NAD induces resistance against RKN pathogenicity likely through the accumulation of tomato basal defense responses rather than the direct effect on the infectivejuveniles behavior.

Potential of nicotinamide adenine dinucleotide (NAD) for management of root-knot nematode in tomato

“…The studies reported here demonstrate that, in both growth room and greenhouse experiments, 1mM NAD provided short term protection against M. incognita and enhanced plant growth of tomato. These findings are supported by our previous study where an application of 5 mM NAD resulted in significantly less J2 penetration at 2 DAI, fewer root galls at 30 DAI and better plant growth compared to the non-treated control ( Abdelsamad et al, 2019 ). None of the three NAD concentrations showed any direct nematicidal effect, confirming that the NAD effect is indirect by stimulating plant defenses ( Abdelsamad et al, 2019 ).…”

“…In previous studies, we demonstrated that exogenous application of 5mM NAD can induce plant defenses in tomato against the root-knot nematode species, M. hapla and suppress nematode root invasion, root galling and egg production, and at the same time stimulate plant biomass ( Abdelsamad et al, 2019 ). The studies reported here demonstrate that, in both growth room and greenhouse experiments, 1mM NAD provided short term protection against M. incognita and enhanced plant growth of tomato.…”

“…Previous investigations on the use of NAD against M. hapla showed that a drench application of 5 mM 24 hr before nematode inoculation, significantly induced defense response pathways, suppressed infective juvenile penetration and increased plant mass in tomato ( Abdelsamad et al, 2019 ). We wanted to further evaluate the potential of NAD to treat and prime tomato seedlings in transplant trays, prior to planting in the field.…”

Tomato Natural Resistance Genes in Controlling the Root-Knot Nematode

“…Many studies indicate that the role of Rme1 is limited to Mi-1 -mediated resistance only and plays no role in disease resistance [9]. Another compound is nicotinamide adenine dinucleotide (NAD), which induces resistance against RKN pathogenicity, likely through the accumulation of tomato basal defense responses rather than the direct effect on the infective juvenile behavior [67]. In addition, the role of SlWRKY3 acts as a positive regulator for the resistance against the RKN-like M. javanica by activating lipids and the hormone-mediated defense-signaling pathway.…”

The essential schistosome tegumental ectoenzyme SmNPP5 can block NAD-induced T cell apoptosis

“…NAD and NAD-cleaving enzymes are also known to impact immunological function in other kingdoms of life. For instance, NAD triggers metabolic profiles in some plants that are associated with resistance to pathogens [ 53 ] and, in tomatoes, NAD has been reported to induce innate immune responses that protect the plants from infection with the root-knot nematode, Meloidogyne hapla [ 54 ]. Additionally, some immune receptors of plants are NADases that have been reported to promote resistance to pathogens [ 55 ].…”