Cytology of Carica papaya, Carica cauliflora and their F1 interspecific hybrids
1998
Siar, S.V. | Geronimo, S.B. | Sierra, Z. | Villegas, V.N. (Philippines Univ. Los Banos, College, Laguna (Philippines). Inst. of Plant Breeding)
The chromosome behavior during microsporogenesis in Carica papaya, Carica cauliflora and their interspecific hybrids was studied to elucidate the observed sterility in the interspecific hybrids. Flora bud sampling for cytological studies was done at 11:30 am on a bright sunny day for both C. papaya and C. cauliflora. For interspecific hybrids, meiotic activity was at its peak at 12:30-1:30 pm for field grown plants and 1:30-2:30 pm for greenhouse grown plants. Meiosis in the parents was normal. The chromosomes showed regular pairing with nine bivalents at diakinesis and separated synchronously to each pole. At telophase 2, tetrades of uniform size was produced. The chromosomes number in both parents was consistent at 2n=18. Pollen fertility was high. An average of 96% and 94% fertility was recorded for C. papaya and C. cauliflora, respectively. The chromosomes of the interspecific hybrids showed very little to non-homology with the chromosomes of the two parents. Variable chromosome counts, presence of univalents, chromosome elimination and marked meiotic aberrations characterized the meiotic behaviour of the interspecific hybrids. These meiotic irregularities lead to the formation of non-functional pollen, thus very low pollen fertility was recorded for the interspecific hybrids
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