Abstract
Early infections of the papaya ringspotvirus-watermelon strain (PRSV-W) in summersquash Cucurbita pepo may causemarketable yield losses of up to 100%. Because control of the viral disease viamanagement of vector insects is notefficient, incorporation of PRSV-W geneticresistance into C. pepo cultivarswould be highly desirable. Althoughresistant accessions have been described inC. ecuadorensis, C.foetidissima, C. maxima and C.moschata, resistant accessions of C.pepo are rare. This paper reports oninterspecific hybridization between C.pepo and a PRSV-W-resistant C.moschata squash accession, and on theearly steps in introgression of thisresistance into the former species. C. pepo cv. Asmara was crossed with twoPRSV-W resistant C. moschataaccessions. Immature F1 (C.pepo× C.moschata) embryos were excised20 days after pollination, and culturedasseptically in two different culturemedia, each under two different lightregimes. No adult plants could berecovered from immature embryos of thecross C. pepo cv. Asmara × C.moschata cv. Piramoita. From the crossC. pepo cv. Asmara × C.moschata cv. Duda, 4 seedlings wererecovered from 6 embryos incubated in agrowth chamber [25° to 28 °C,16 hours of light with 1500–2000 lux/ 8 hdark period] immediately after excision andinoculation in a culture medium [=Murashige and Skoog (MS) + 0.01 mg/L of IAA(indolacetic acid) + 0.1 mg/L of Kinetin],without an intervening dark period. F1 (C. pepo × C. moschata)plants were fertile, and upon selfingyielded viable F2 seeds. PRSV-Wresistance was assessed in the F2 (C. pepo × C. moschata) population,using C. pepo cv. Asmara and C.moschata cv. Duda, respectively, as thesusceptible and resistant (tolerant)checks. Plants were mechanically inoculatedwith a known PRSV-W isolate. The F2population showed a PRSV-W responseintermediate between those of the parentalaccessions, and estimates of the meandegree of dominance indicates incompletedominance in the direction ofsusceptibility. The mean broad-senseheritability estimate of PRSV-W resistancewas 0.48, a medium to high value,indicating the likelihood of a significantresponse to selection for resistance. Theintrogression of the resistance to PRSV-Wof C. moschata into C. peposeems to be technically viable.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
