How Durable is Root Knot Nematode Resistance in Tomato?

Abstract

Among the plant parasitic nematodes, root knot nematode (RKN) is the most devastating in tomato growing regions. Controlling RKN mostly relies on nematicides. Since chemical application is limited due to adverse environmental effect, alternative approaches are required. Although there are some alternatives, but resistance cultivars are getting popularity in the farmer's field because of simplicity, cost-effective and environment safety. Genes conferring resistance to RKN have already been identified followed by the introgression into elite cultivars. Currently, natural resistance genes (R genes) are used in conventional breeding programmes. Simultaneously, molecular research is going on to characterize and map the linked markers for the detected resistant phenotypes. Currently, it is a prominent threat to maintain the durability of existing R genes. However, durability of host resistance govern by co-evolution of resistance genes from plants and (a)virulence genes from nematodes. So, understanding the mechanisms underlying co-evolution is essential for the durability of R genes. Here we review the existing potential natural resistance in tomato against RKN, currently used resistance mechanisms between RKN and tomato, influential factors of durability of natural resistance genes and opportunity to get more durable resistance in tomato.

Cucumis metuliferus reduces Meloidogyne incognita virulence against the Mi1.2 resistance gene in a tomato–melon rotation sequence

“…Similar results were reported with potato germplasm containing the GpaIV adg and Gpa5 genes pyramided, in which fewer Globodera pallida cysts developed than in genotypes carrying each single gene . Regarding tomato, several single dominant R ‐genes that are also resistant against Mi1 .2‐virulent RKN populations and stable at high soil temperatures (32 °C) have been identified and mapped in different chromosomes . Such genes could be pyramided to obtain stronger and durable resistance in tomato.…”

Tomato Natural Resistance Genes in Controlling the Root-Knot Nematode

“…Tomatoes, like all plants, undergo several modes for protection and immunity (Figure 2). The plant has an innate immune system that can recognize pathogen-associated molecular patterns (PAMPs) [29]. PAMP-triggered immunity (PTI) is the first defense line of response of the plant to pathogens.…”

“…In tomatoes, ten genes, Mi-1 to Mi-9 and Mi-HT , for resistance to root-knot nematodes have been reported [11,29]. They all originate from wild species, and only Mi-1 has been reported as available for controlling the disease [29].…”

Plant defense responses in monocotyledonous and dicotyledonous host plants during root-knot nematode infection

“…Moreover, Mi-1.2-mediated resistance is effective only against the three aforementioned species but is ineffective against other harmful RKN species, such as M. enterolobii and M. hapla (El-Sappah et al 2019;Kiewnick et al 2009). There are also reports on nine other root-knot nematode resistance genes in wild species of tomato: Mi-2 to Mi-9 and MiHT, but unlike Mi-1.2, they have not been successfully transferred to cultivated tomatoes (Rashid et al 2017;Wu et al 2009). There are also some studies that indicate that the Me resistance gene in pepper (Capsicum annuum) confers resistance to RKNs (Djian-Caporalino et al 2007) and that the Mex-1 gene in coffee (Coffea arabica) confers resistance to M. exigua (Noir et al 2003).…”

“…Several review articles address the interactions between plants carrying resistance genes and RKN species (Barbary et al 2015;El-Sappah et al 2019;Rashid et al 2017;Roberts 1992;Seid et al 2015). In addition, there are also recent review articles presenting in a broader sense some topics associated with the field of plant parasitic nematode-plant interactions (Kaloshian and Teixeira 2019;Sato et al 2019; Siddique and Grundler Fig.…”