Construction of a genome-anchored, high-density genetic map for melon (Cucumis melo L.) and identification of Fusarium oxysporum f. sp. melonis race 1 resistance QTL

Abstract

Four QTLs and an epistatic interaction were associated with disease severity in response to inoculation with Fusarium oxysporum f. sp. melonis race 1 in a recombinant inbred line population of melon. The USDA Cucumis melo inbred line, MR-1, harbors a wealth of alleles associated with resistance to several major diseases of melon, including powdery mildew, downy mildew, Alternaria leaf blight, and Fusarium wilt. MR-1 was crossed to an Israeli cultivar, Ananas Yok'neam, which is susceptible to all of these diseases, to generate a recombinant inbred line (RIL) population of 172 lines. In this study, the RIL population was genotyped to construct an ultra-dense genetic linkage map with 5663 binned SNPs anchored to the C. melo genome and exhibits the overall high quality of the assembly. The utility of the densely genotyped population was demonstrated through QTL mapping of a well-studied trait, resistance to Fusarium wilt caused by Fusarium oxysporum f. sp. melonis (Fom) race 1. A major QTL co-located with the previously validated resistance gene Fom-2. In addition, three minor QTLs and an epistatic interaction contributing to Fom race 1 resistance were identified. The MR-1 × AY RIL population provides a valuable resource for future QTL mapping studies and marker-assisted selection of disease resistance in melon.

QTL Mapping and Marker Development for Tolerance to Sulfur Phytotoxicity in Melon (Cucumis melo)

“…A previously described RIL population (Branham et al, 2018) consisting of 170 lines generated from a cross of MR-1 and Ananas Yok'neum (AY) was evaluated for elemental sulfur tolerance. The Israeli cantaloupe cultivar Ananas Yok'neum was the sulfur tolerant parent and the inbred C. melo line MR-1 (Thomas, 1986) was the sensitive parent ( Figure 1).…”

“…In this study, we utilized the high-density, genome-anchored genetic map available for the MR-1 × AY RIL population (Branham et al, 2018) to identify QTL associated with tolerance to vaporized sulfur. In addition, PCR-based markers for the major QTL were developed and tested in the population and various elite germplasm for linkage to sulfur tolerance and should be useful to breeders utilizing a marker assisted breeding scheme to increase the efficiency of sulfur tolerance introgression into elite cultivars.…”

A high-density SNP-based genetic map in Pelteobagrus vachelli and mapping of growth, sex determination and hypoxia tolerance related loci

“…For weight-related traits, the CW and GW LOD significance thresholds varied from 3 to 3.6 and from 5 to 5.1, respectively, based on the permutation test. A total of 36 QTLs associated with weight-related traits were detected in 10 LGs using the interval mapping algorithm, including 4 significant GW QTLs (qW14-a, qTL3-a, qTL14-a and qHL14-a; Fig. 3A, B, C) and 19 significant CW QTLs, with LOD scores ranging from 3.26 to 5.52 (Table 4).…”

“…In addition, significant QTLs for weight, gender and disease resistance in these fish species have been detected. MAS using QTL analysis is the most effective breeding method for many animals and plant species and it is a direct choice for genotyping the control trait loci [ 10].…”

Advances in Melon Breeding (<em>Cucumis melo</em> L.): An Update

“…Generally, cultivars with a longer shelf life (LSL types) are thought of by customers as having low fruit quality and therefore, present minimal acceptability (Wolff and Dunlap, 1995). Although, most of the breeders concur that powdery mildew resistance and fusarium are essential and fundamental demands of farmers for the modern melon varieties (Capel et al, 2010; Branham et al, 2018). Also, insect pest management is a significant component which benefits commercial yield by providing a much better yield safety measures, reduced waste along with much better fruit quality (Ramamurthy and Waters, 2015).…”