QTL mapping and marker development for tolerance to sulfur phytotoxicity in melon (Cucumis melo)

Authors: BRANHAM, SANDRA - Clemson University; DALEY, JAMES - Clemson University; Levi, Amnon; HASSELL, RICHARD - Clemson University; Wechter, William - Pat

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2020
Publication Date: 7/22/2020
Citation: Branham, S., Daley, J., Levi, A., Hassell, R., Wechter, W.P. 2020. QTL mapping and marker development for tolerance to sulfur phytotoxicity in melon (Cucumis melo). Frontiers in Plant Science. 11:1097-1105. https://doi.org/10.3389/fpls.2020.01097.
DOI: https://doi.org/10.3389/fpls.2020.01097

Interpretive Summary: Elemental sulfur is an effective, inexpensive fungicide for many foliar pathogens, but severe phytotoxicity prohibits its use on many melon varieties. Sulfur phytotoxicity causes chlorosis and necrosis of leaf tissue, leading to plant death in the most sensitive lines, while other varieties have little to no damage. Genetic mapping of a segregating recombinant inbred line population to identify genetic regions associated with tolerance to sulfur in melon. One major (qSulf-1) and two minor (qSulf-8 and qSulf-12) genetic regions were associated with sulfur tolerance in the population. Genetic markers were developed and validated for linkage to sulfur tolerance in a set of melon cultivars. These markers can be incorporated into melon breeding programs for introgression of sulfur tolerance into elite melon germplasm.

Technical Abstract: Elemental sulfur is an effective, inexpensive fungicide for many foliar pathogens, but severe phytotoxicity prohibits its use on many melon varieties. Sulfur phytotoxicity causes chlorosis and necrosis of leaf tissue, leading to plant death in the most sensitive lines, while other varieties have little to no damage. A high-density, genotyping-by-sequencing (GBS)-based genetic map of a recombinant inbred line (RIL) population segregating for sulfur tolerance was used for a quantitative trait loci (QTL) mapping study of sulfur phytotoxicity in melon. One major (qSulf-1) and two minor (qSulf-8 and qSulf-12) QTL were associated with sulfur tolerance in the population. The development of Kompetitive Allele-Specific PCR (KASP) markers developed across qSulf-1 increased QTL resolution by 59 kb. The markers were validated for linkage to sulfur tolerance in a set of melon cultivars. These KASP markers can be incorporated into melon breeding programs for introgression of sulfur tolerance into elite melon germplasm.