INTERSPECIFIC REPRODUCTIVE BARRIERS AND GENOMIC SIMILARITY AMONG THE ROUGH-SEEDED LUPINUS SPECIES

The nature of reproductive barriers and meiotic behaviour of chromosom es were studied in interspecific hybrids among the six rough-seeded Lu pinus species. Out of 30 different interspecific crosses attempted in all possible combinations, eight produced viable F-1 seeds. These succ essful crosses involved L. cosentinii, L. digitatus, L. atlanticus and L. pilosus. Crosses of L. princei with other species resulted in shri velled F-1 seed in all combinations. In contrast to previous reports, crosses of L. palaestinus with all other rough-seeded lupins were inco mpatible as no F-1 hybrids were obtained. Barriers to interspecific re production were identified as nucleo-cytoplasmic and embryo-endosperm incompatibility in unsuccessful crosses, and chromosomal imbalances in F-1 hybrids. Gene transfer is possible among L. cosentinii, L. digita tus and L. atlanticus, which produced F-1 seed. Patterns of chromosome configurations in F-1 meiotic cells suggested that these species have al least two genomes partially in common, but include inversions and translocations. The genome of L. atlanticus is closer to L. digitatus than to L. cosentinii, and that of L. pilosus is closer to L. atlantic us than to L. cosentinii. L. princei appears to have an isolated genom e within the rough-seeded Lupinus species.