Embryo rescue from interspecific crosses in the genus Actinidia (kiwifruit)

Within the framework of a broad program of interspecific crosses involving different Actinidia species and ploidy races, we carried out an assay of in terspecific hybridization using a small number of the Actinidia species ava ilable in European repositories. Our aim was to conduct a preliminarily ass essment of the degree of crossability occurring in the genus and the effect iveness of different techniques and media in rescuing interspecific hybrids . A set of culture media was developed to replace the hybrid embryo's defic ient endosperm to ensure survival of the embryos at the globular and heart stages. In several crosses immature embryos that reached the torpedo stage were rescued when incubated in the proper media. The embryo rescue was the unique tool which led to hybrid plantlets for four crosses: A. kolomikta x A. chinensis, A. polygama x A. valvata, A. arguta Issa x A. polygama and A. kolomikta x A. deliciosa. Flow cytometry was used to check the ploidy leve l of the parental genotypes and the progeny. A wide interspecific crossabil ity was found in Actinidia that involved species belonging to the different sections on the basis of traditional taxonomy.