Anthere culture of tetraploid somatic hybrids as a crucial tool for starting Practical introgression breeding from allied species in eggplant (S. melongena L.)

The major limits for practical exploitation of the somatic hybrids between eggplant and its wild relatives has been their sterility and tetraploidy which have prevented their incorporation into breeding programs. We successfully employed anther culture to bring back the ploidy level to the diploid status of tetraploid interspecific hybrids between eggplant and the allied species S. integrifolium (=S. aethiopicum gr aculeatum) and S. aethiopicum gr gilo. Both the relative species are resistant to Fusarium oxysporum f. sp. melongenae and to some strains of Ralstonia solanacearum which are very destructive diseases on eggplant. Dihaploid androgenetic plants were obtained from the somatic hybrid between eggplant and S. integrifolium and from tetraploid backcrossed plants between the somatic hybrid with S. aethiopicum and eggplant. Phenotypical, molecular, biological and biochemical characterization, and also artificial inoculation with Fusarium oxysporum are consistent with a recombination between the genomes of the species involved in the hybridizations. Dihaploids resistant to Fusarium have been successfully backcrossed with eggplant and incorporated in our breeding program. After 4-6 cycles of backcrosses, lines with improved features of fruits and plant characteristics were obtained. The subsequent 2-4 selfing cycles, allowed to fix superior lines with interesting agronomical traits. The fruit weight increased, reaching that of the recurrent eggplant line employed in the backcrosses. Selected pure lines were completely resistant to Fusarium wilt. In the last years, the best advanced introgressed lines from the two single allied species above mentioned have been inter-crossed each other and with the Verticillium tolerant lines derived from a sexual crosses between eggplant and S. sodomaeum (= S. linneanum). Besides their utility as potential valuable breeding materials, the lines obtained are going to be utilized in genetic and molecular studies about the resistance/tolerance to Fusarium and Verticillium wilts. from S. integrifolium, S. aethiopicum gr gilo and S. sodomaeum and to biochemical and nutritional characterization to discover other possible useful genes and features introgressed from the allied species into eggplant.