Development of a codominant CAPS marker linked to PRSV-P resistance in highland papaya.
Development of resistant papaya varieties is widely considered the best strategy for long-term control of the papaya ringspot virus type P (PRSV-P). Several species of "highland papaya" from the related genus Vasconcellea exhibit complete resistance to PRSV-P, and present a valuable source of resistance genes with potential for application in Carica papaya. The objectives of this study were two fold; to identify molecular markers linked to a previously characterised PRSV-P resistance gene in V. cundinamarcensis (psrv-1), and to develop codominant marker based strategies for reliable selection of PRSV-P resistant genotypes. Using a bulked segregant analysis approach, dominant randomly amplified DNA fingerprint (RAF) markers linked to prsv-1 were revealed in the resistant DNA bulk, which comprised F2 progeny from a V. parviflora (susceptible) x V. cundinamarcensis (resistant) interspecific cross. One marker, Opk4_1r, mapped adjacent to the prsv-1 locus at 5.4 cM, while a second, Opa11_5r, collocated with it. Sequence characterisation of the Opk4_1r marker permitted its conversion into a codominant CAPS marker (PsiIk4), diagnostic for the resistant genotype based on digestion with the restriction endonuclease PsiI. This marker mapped within 2 cM of the prsv-1 locus. Psilk4 was shown to correctly identify resistant genotypes 99% of the time when applied to interspecific F2 progeny segregating for the resistant character, and has potential for application in breeding programs aimed to deliver the PRSV-P resistance gene from V. cundinamarcensis into C. papaya.
Dillon
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CSIRO, Ensis genetics, Banks Street, Yarralumla, ACT 2600, Australia. Shannon.Dillon@csiro.au
Ramage
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Ashmore
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Drew
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D031241:Caricaceae / Q000235:genetics* / Q000821:virology; D016172:DNA Fingerprinting; D008040:Genetic Linkage; D005819:Genetic Markers; D005838:Genotype; D006824:Hybridization, Genetic; D007113:Immunity, Innate / Q000235:genetics; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D017800:Potyvirus / Q000502:physiology*; D015183:Restriction Mapping
D005819:Genetic Markers