Show simple item record

dc.contributor.advisorWessel-Beaver, Linda
dc.contributor.authorMcPhail Medina, Robert Alan
dc.date.accessioned2018-11-14T16:33:39Z
dc.date.available2018-11-14T16:33:39Z
dc.date.issued2010
dc.identifier.urihttps://hdl.handle.net/20.500.11801/1252
dc.description.abstractEl Papaya ringspot virus, cepa de sandía (PRSV-W), es una de las enfermedades más limitantes en la producción de calabaza (Cucurbita moschata Duchesne). Se ha reportado que el cultivar ‘Nigerian Local’ (NL), proveniente de África, posee una resistencia monogénica recesiva a PRSV-W. Esfuerzos previos conducidos a la incorporación de resistencia a PRSV-W en genotipos locales susceptibles mediante un programa de retrocuzamiento sugieren que la herencia es más compleja. Las poblaciones utilizadas en el presente estudio provienen del cruce entre el cultivar resistente NL, con cada uno de los cultivares susceptibles, ‘Soler’, ‘Taína Dorada’, ‘Verde Luz’ y ‘Waltham’. Las plantas se inocularon mecánicamente con PRSV-W en etapa de cotiledones y se observaron por 20 días bajo condiciones de invernadero. Los síntomas que predominaron fueron: mosaicos, deformación, pústulas, puntos cloróticos y amarillamiento de venas, principalmente en hojas en una amplia gama de severidad. El cultivar NL lució consistentemente libre de síntomas. Al agrupar las cuatro clases de severidad (de 0-3, donde 0= plantas libre de síntomas y 3= plantas con síntomas severos) entre resistentes y susceptibles, cada población F2 ajustó a un radio de segregación 1:3 (resistentes: susceptibles). Las plantas F2 clasificadas como resistentes se trasladaron al campo donde la mayoría se mantuvo sin síntomas evidentes por el resto de su ciclo de vida y a partir de estas se generaron familias F3. La respuesta de las familias F3 al ser inoculadas con PRSV-W fue variada: pocas presentaron resistencia uniforme (libre de síntomas) o susceptibilidad uniforme, y la mayoría presentaron una atenuación de síntomas (mayormente severidad=1), en comparación a sus respectivos parentales. Este estudio sugiere que la herencia de la resistencia a PRSV-W es más compleja que una monogénica recesiva y demostró la importancia de realizar un estudio de progenie de individuos resistentes cuando se selecciona para resistencia al PRSV-W en el cultivo de calabaza.
dc.description.abstractPapaya ringspot virus, watermelon strain (PRSV-W), is one of the most limiting diseases in pumpkin and squash (Cucurbita moschata Duchesne) worldwide. A monogenic recessive resistance to PRSV-W has been reported in the Africa landrace C. moschata cv. ‘Nigerian Local’ (NL). The experience during a backcrossing program to incorporate resistance found in NL into local tropical genotypes suggests that inheritance of PRSV-W is more complex than a single recessive gene. F1, F2, backcross and F3 populations were derived from crosses between NL and each one of the susceptible cultivars, ‘Taína Dorada’, ‘Verde Luz’, ‘Soler’ and ‘Waltham’. The populations were mechanically inoculated with PRSV at cotyledon stage and were observed for about 20 days under greenhouse conditions. The range of symptoms was very similar between each population throughout all the evaluations under greenhouse conditions: mosaics or mottling, distortions, blisters, chlorotic spots and discoloration of veins were present in a wide range of severity. Inoculated plants of NL remained completely free of symptoms. When the four classes of disease severity (0-3, where 0= symptom-free plants and 3= severe symptoms plants) were combined for each F2 population, a 1:3 (resistant: susceptible) ratio was observed as would be expected with a single recessive gene for resistance. Many of the resistant F2 individuals showed some degree of very mild symptoms, rather than being symptom-free. When these F2 individuals classified as resistant were planted in the field, most of these plants remained with very mild PRSV-W symptoms or symptom-free. The response of F3 families derived from resistant F2 plants was diverse: very few showed uniform resistance or uniformly severe symptoms and most showed weak PRSV-W symptoms. This study suggests that inheritance of resistance to PRSV-W is more complex than a single recessive gene, and demonstrates the importance of progeny testing of resistant individuals when selecting for PRSV-W resistance in pumpkins or squash.
dc.description.sponsorshipLa investigación fue apoyada económicamente por: “USDA-CRREES – Hispanic Serving Institutions Education Grants Program Award No. 2006-38422-17106, USDA- CSREES-TSTAR Program Award No. 2006-34135-17545 (PR00TSTAR117) y PR00TSTAR123 Program Award No. 2008-34135-19505, USDA-CSREES-HATCH, PR 00421”, y la Estación Experimental de Puerto Ricen_US
dc.language.isoesen_US
dc.subjectPapayaen_US
dc.subjectCalabazaen_US
dc.subjectCultivares Tropicalesen_US
dc.titleHerencia de la resistencia a papaya ringspot virus-w en cultivares tropicales de calabaza (Cucurbita Moschata)en_US
dc.typeThesisen_US
dc.rights.licenseAll rights reserveden_US
dc.rights.holder(c) 2010 Robert Alan McPhail Medina.en_US
dc.contributor.committeeVerle Rodríguez, Jose Carlos
dc.contributor.committeeCianzio, Silvia
dc.contributor.committeeO'Farrill, Hipólito
dc.contributor.representativeSantana, Carmen
thesis.degree.levelM.S.en_US
thesis.degree.disciplineAgronomyen_US
dc.contributor.collegeCollege of Agricultural Sciencesen_US
dc.contributor.departmentDepartment of Crops and Agro-Environmental Sciencesen_US
dc.description.graduationYear2010en_US


Files in this item

Thumbnail

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 degree at UPR-Mayagüez.

Show simple item record

All rights reserved
Except where otherwise noted, this item's license is described as All Rights Reserved