Crossability of Brassica tournefortii and B-rapa, and morphology and cytology of their F1 hybrids

The crossability between Brassica tournefortii (TT, 2n = 20) and Brassica mpn (AA, 2n = 20) and the cytomorphology of their F, hybrids were studied. Hybrids between these two species were obtained only when B, tournefortii was involved as a female parent. The hybrid plants were intermediate for most of the morphological attributes and were found to be free from white rust under field conditions. The F-1 plants showed poor pollen fertility, although occasional seed set was achieved from open pollination. Self-pollination or backcrosses did not yield any seeds in these plants. The occurrence of chromosome association ranging from bivalents (0-7), trivalents (0-2) to a rare quadrivalent (0-1) in the dihaploid hybrids indicates pairing between the T and A genomes. The homoeologous pairing coupled with seed set in the F, plants offer an opportunity for interspecific gene transfers from B, tournefortii to B. rapa and vice-versa through interspecific hybridization.