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Cytomorphology of Brassica napus × B. rapa hybrids and patterns of variation in the F2 derivatives
- Choudhary, Bagada Ram, Joshi, Purushottam
- Caryologia 2012 v.65 no.4 pp. 316-321
- Brassica napus, Brassica rapa subsp. dichotoma, Brassica rapa subsp. trilocularis, chromosomes, crossing, females, genetic variation, genome, hybrids, meiosis, metaphase, parents, pollen, transgressive segregation
- The present study was carried out to determine crossability between Brassica napus and B. rapa , to elucidate chromosome homoeology between different Brassica genomes in the F ₁ hybrids and to estimate genetic variability in F ₂ progenies of the crosses. Crosses between B. napus (AACC, 2 n = 38) and B. rapa (AA, 2 n = 20) vars. brown sarson , yellow sarson and toria were attempted and the hybrid derivatives were advanced to F ₂ generation. Hybrid recoveries were higher when B. napus was used as a female parent. The F ₁ plants were luxuriant in growth and intermediate to their progenitor parents for morphological attributes. The meiotic studies of F ₁ plants (AAC, 2 n = 29) showed 10 bivalents in the majority of pollen mother cells analyzed. A maximum of 12 II was found in a few cells. The occurrence of multivalent associations as trivalent and quadrivalent at metaphase I, and a bridge-fragment configuration at anaphases were attributed to homoeology between A and C genomes. In the F ₂ generation, a high percentage of plants resembling B. napus were observed. Transgressive segregation in both directions was observed for yield contributing traits.