MORPHOLOGICAL, MOLECULAR AND CYTOLOGICAL ANALYSES OF CARICA-PAPAYA X CARICA-CAULIFLORA INTERSPECIFIC HYBRIDS

Morphological, molecular and cytological analyses were performed to as sess the hybridity of 120 putative interspecific hybrids of Carica pap aya L. x C. cauliflora Jacq. In the putative interspecific hybrids the number of main leaf veins was intermediate between the two parents wh ile the hermaphrodite flower sex form and the low vigour were distinct ive features of these hybrids. Petiole length, stem diameter, leafleng th, leaf width and flower colour were similar to C. papaya, whereas le af shape, type, serration, venation, petiole hairiness and flower shap e were similar to C. cauliflora. Markers generated by the polymerase c hain reaction using 72 10-mer primers (random amplified polymorphic DN A) revealed a high level of polymorphism (64%) between C. papaya and C . cauliflora. Seventeen of these primers yielded reliable and easily s corable polymorphic banding patterns that were further screened to rev eal hybrids. A range of 1-5 RAPD primers consistently confirmed that a ll 120 plants were genetic hybrids, with all of them containing at lea st one band from the male parent. Cytological analysis revealed that 7 -48% of the cells in many of the interspecific hybrids were aneuploid suggesting that chromosome elimination was occurring. The frequency of aneuploid cells was negatively associated (r = 0.88) with the number of bands from the male parent integrated into the hybrid. Pollen ferti lity of the hybrids was from 0.5 to 14.0% while C. papaya and C. cauli flora had 88.0-99.0% and 90.0-97.0% fertile pollen, respectively.