Genotype, Temperature, and Sampling Date Affect Embryogenesis in Asparagus Anther Culture

Asparagus (Asparagus officinalis L.) anthers from flowers of field-grown plants were cultured for five genotypes, four incubation temperatures, and three sampling dates. Treatments were evaluated for total and embryogenic callus production. Incubating anthers at 35C was optimal for initiating embryogenic callus for three genotypes. Another line performed best and equally well at 29 and 32C, while one was recalcitrant to embryogenic callus formation at the temperatures evaluated. For all genotypes, almost half of the anthers produced callus for at least one temperature treatment, hut the percentage of these calli that was embryogenic ranged from 0% to 50%. Sampling date affected response only for specific genotype-temperature combinations. Embryo recovery ranged from six to 14 per callus. For the four responsive genotypes, 77% to 100% of plantlets was haploid. Culturing anthers at several temperatures ranging from 29 to 35C, with repeated samplings of flowers from the field, likely will allow recovery of haploid embryos from many selections. This result will expand the germplasm base to develop all-male asparagus hybrids.