Breeding melon for resistance to Fusarium wilt: recent developments

Abstract

Melon Fusarium wilt (MFW), caused by Fusarium oxysporum f. sp. melonis (Fom), is one of the most destructive diseases of melon (Cucumis melo L.). The development and deployment of resistant cultivars is generally considered to be the best approach to control MFW. Based on the host resistance genes associated with variants of this pathogen, Fom isolates were classified into four physiological races designated 0, 1, 2, and 1,2. Two dominant resistance genes, Fom-1 and Fom-2, control resistance to races 0 and 2, and 0 and 1, respectively. Fom isolates classified as race 1,2 are able to induce disease in melon lines carrying the above resistance genes. Many sources of resistance to Fom races 0, 1, and 2 have been reported. Partial resistance to race 1,2 controlled by polygenic recessive genes was only detected in a few Far Eastern melon accessions, except for the breeding line BIZ where complete resistance was described. Identification of DNA markers tightly linked to genes conferring resistance to Fom has immediate application in MFW resistance breeding programs. The Fom-2 gene has been cloned, and it encodes a protein with a nucleotide binding site (NBS) and leucine-rich repeats domain (LRR). Based on the sequence of this domain, some molecular markers linked to this gene were developed. Several DNA markers linked to Fom-1 have also been described. However, the usefulness of these markers was variety-dependent. Therefore, their combined use would be very useful in marker assisted selection for introducing resistance to Fom races 0 and 2 in melon. Recently, these markers were used for the positional cloning of this gene, which encoded a protein with a NBS–LRR domains that shows similarity to the toll and interleukin-1 receptores (TIR). Regarding Fom race 1,2, nine QTL were detected on five linkage groups by composite interval mapping. In this paper we review the current knowledge of MFW disease, and focus on genetic resistance to Fom and marker-assisted selection for resistance.

Scanning Electron Microscopy study of root tissue of muskmelon: Transferring Fusarium wilt resistance from snapmelon to muskmelon

“…Hans (F.o.m) causes muskmelon Fusarium wilt (MFW). The MFW decreases both fruit yield and quality apart forcing intensive use of chemical fungicide sprays (Gordon et al 1990, Oumouloud et al, 2013. The formation of perennating chlamydo spores in soil by this fungus and the ability to infect and colonize the root system of non-host plants and melon rotation crops equips it to sustain its population in soil over gap and crop cover other than melon (Gordon et al, 1989).…”

“…The synthesis and amount of secondary metabolites i.e. phytoalexins, enzymes defending reactive oxygen species (ROS), and cell wall-building processes like necrosis, callose deposition and lignification in response to invasion by fungal pathogens play a vital role in imparting resistance to F.o.m infection (Oumouloud et al, 2013). The F.o.m.…”

“…Therefore, resistance against FWD in muskmelon cultivars is governed by an array of morphological, biochemical and enzymatic characteristics of the melon root. Oumouloud et al (2013) have reported that the root morphological traits and the ROS neutralizing enzymes are involved in imparting resistance in melon genotypes against FWD. Thus, this study was conducted to elucidate the root anatomical differences among the susceptible and resistant muskmelon hybrids for F.o.m infection and the effect of FWD on the fruit yield and quality.…”

Marker-assisted selection of Fusarium wilt-resistant and gynoecious melon (Cucumis melo L.)

“…Further analysis has shown that FOM-2 has two structural and functional domains, the nucleotide-binding (NB)-adaptor shared by APAF-1, R proteins, and CED-4 (ARC) and the LRR, which are present in typical R genes. Some markers have been developed in previous studies for the Fom-2 gene (Oumouloud et al, 2013); however, most of these molecular markers were designed for the thick-rind melon and are not useful for the Chinese thin-rind melon (oriental melon). In the present study, we developed a new molecular marker for melon wilt and verified it for both thick-and thin-rind melons.…”

Development of a Fusarium oxysporum f. sp. melonis functional GFP fluorescence tool to assist melon resistance breeding programmes

“…The identification of Fom ‐ resistant traits represents a fundamental objective in melon breeding programmes. Efforts have been devoted to searching for natural sources of resistance, and in characterizing the molecular basis of melon resistance to Fom (Burger et al ., ; Perchepied & Pitrat, ; Álvarez et al ., ; Oumouloud et al ., , ). The use of molecular tools has contributed to a better characterization of the defensive response of melon accessions to Fom isolates (Oumouloud et al ., ; Haegi et al ., ).…”