STUDIES ON THE GENETICS OF PRSV-P RESISTANCE GENES IN INTERGENERIC HYBRIDS BETWEEN CARICA PAPAYA AND VASCONCELLEA QUERCIFOLIA

Papaya ringspot virus (PRSV-P) is the most widespread and destructive disease of papaya (Carica papaya). Successful introgression of a PRSV-P resistance gene(s) into the papaya gene pool was made possible through intergeneric hybridization with V. quercifolia followed by backcrossing.
Previously, a single dominant gene for PRSV-P in V. pubescens was mapped and assumed to be a kinase gene.
We studied a homologous kinase gene in V. quercifolia and its mode of inheritance.
Segregating populations were manually inoculated and screened for PRSV-P resistance/susceptibility.
Presence of the resistance phenotype among the majority of the hybrids indicated high stability of gene inheritance through successive backcrosses generations.
Since the ratio of susceptible to resistant plants ranged from 4:1 to 1:3, it is still not clear whether the resistant phenotype in V. quercifolia is controlled by a single dominant gene or multiple genes.
The resistance was confirmed against Philippines and Australian PRSV-P virus strains which suggested that the resistance gene could be effective to confer the resistance to virus strains in other countries.
Sixteen primer pairs targeting SSR loci on the candidate kinase gene were designed and tested on the segregating populations.
No SSR markers were linked to the resistance gene in the present study.
However, two useful SSR markers, SP10 and SP16, have been developed.
The SP16 marker confirmed the hybridity of F₁ hybrids and suggested some chromosomal elimination from V. quercifolia. However, further investigations are required to develop a molecular marker that will identify the resistant genotype.

III International Symposium on Papaya

S. Alamery, R. Drew

interspecific hybridization, inheritance of resistance gene, Papaya ringspot virus, molecular marker, Australian PRSV-P strain

https://doi.org/10.17660/ActaHortic.2014.1022.5