Show simple item record

dc.contributor.advisorLinares-Ramírez, Angela M.
dc.contributor.authorSeda-Martinez, Wilfredo
dc.description.abstractViruses of the Potyviridae can infect all cucurbit crops. General symptoms are well-described, but there are no known studies documenting yield and fruit quality loss in tropical pumpkin (Cucurbita moschata Duchesne). Papaya ringspot virus (PRSV) is among the most common of the potyviruses found in Puerto Rico. Two sources of resistance are well known in C. moschata: ‘Nigerian Local’ (NL) and ‘Menina’ (MEN). The inheritance of resistance from NL has been previously studied, but no inheritance studies have been reported for MEN, nor is it known if resistance to PRSV in NL is allelic to that in MEN. Therefore, the objectives of this research were to study (1) the impact of potyvirus on tropical pumpkin at the field level and (2) the inheritance of PRSV resistance in mechanically inoculated F2 populations derived from both sources of resistance, and test for allelism in a NL x MEN F2 population. Control plants and plants inoculated with PRSV, ZYMV or PRSV+ZYMV of six different genotypes were transplanted to the field. Number of fruit and fruit weight per plant, and average fruit size were reduced up to 50% in virus-inoculated plants. In the inheritance study susceptible genotypes were ‘Verde Luz’ (VL), ‘Taina Dorada’ (TD) and ‘TP411’ (TP). The third to fifth leaf of inoculated seedlings were rated on a 0 to 4 scale for disease severity and scores were combined to convert to a 0 to 12 scale. F2 populations using NL as the source of resistance had a nearly normal distribution with an average disease severity of 5.23 in NL x TD and 6.25 in VL x NL. In contrast, the F2 populations with MEN were strongly skewed towards resistance with an average severity of 3.38 in MEN x TD, 2.27 in VL x MEN and 2.80 in TP x MEN. The NL x MEN F2 population was highly skewed, with an average combined severity of 0.840. It segregated 224:14 (R:S) when a combined severity of <4 was considered resistant. Segregations in resistant x susceptible F2 populations were variable, depending on how severity scores were combined into the resistant versus susceptible classes. However, most segregations suggested that at least two genes are involved in the inheritance of resistance to PRSV for both NL and MEN. The data clearly indicate that at least some of the genes for resistance in NL and MEN are different. Considering the level of resistance conferred by both NL and MEN, both sources, either alone or combined, will be useful in a breeding program.  en_US
dc.description.sponsorshipUSDA “Coordinated Agricultural Project” (CAP) titled “CucCAP: Leveraging Applied Genomics to Increase Disease Resistance in Cucurbit Crops” Specialty Crop Research Initiative grant no. 2015-51181-24285 and by Hatch accession no. 1000526 from the USDA National Institute of Food and Agricultureen_US
dc.rightsCC0 1.0 Universal*
dc.subject.lcshPotyvirus diseasesen_US
dc.subject.lcshCucurbita pepo -- Disease and pestsen_US
dc.subject.lcshPapaya ringspot virusen_US
dc.titleThe effect of two potyviruses on development and yield in tropical pumpkin and the inheritance of resistance to papaya ringspot virusen_US
dc.title.alternativeEl efecto de dos potyvirus en el desarrollo y rendimiento de calabaza tropical y la herencia de genes de resistencia al virus de la mancha anular de la papayaen_US
dc.rights.holder(c) 2019 Wilfredo Seda-Martinezen_US
dc.contributor.committeeRodrigues Verle, Jose Carlos
dc.contributor.representativeKolterman, Duane
dc.contributor.collegeCollege of Agricultural Sciencesen_US
dc.contributor.departmentDepartment of Crops and Agro-Environmental Sciencesen_US

Files in this item


This item appears in the following Collection(s)

  • Theses & Dissertations
    Items included under this collection are theses, dissertations, and project reports submitted as a requirement for completing a graduate degree at UPR-Mayagüez.

Show simple item record

CC0 1.0 Universal
Except where otherwise noted, this item's license is described as CC0 1.0 Universal