Contributions of Biotechnology to Asparagus Breeding in Argentina

Garden asparagus (Asparagus officinalis L.) is an economically important horticultural crop, susceptible to pathogenic soil fungi of the genus Fusarium. These fungi cause stem, crown and root rot, a major disease all over the world that is difficult to control by the use of chemicals and cultural practices. The development of resistant/tolerant cultivars appears to be the best alternative for control; however, the asparagus-Fusarium pathosystem is complex and advances in this regard have not been very successful. The species is perennial and dioecious, which hinders the breeding process, but it can be asexually and sexually reproduced and in vitro manipulated. In Argentina, imported open-pollinated cultivars and F1 and F2 clonal hybrids are grown, which are susceptible to Fusarium and not necessarily adapted to local conditions. In 1992, an asparagus breeding program was started in Balcarce, in collaboration with another national research group, to (a) generate adapted and good yielding cultivars and (b) explore potential sources of Fusarium resistance. Various biotechnologies were used in an attempt to generate and/or introduce genetic variability for the trait (gametophyte selection, in vitro selection of plants and calluses, interspecific hybridization followed by in vitro ovule culture) and to clone elite genotypes (micropropagation and somatic embryogenesis) to produce clonal hybrids. The principal results of the application of these biotechnologies are summarized in this review. _____________________________________________________________________________________________________________