Colchicine-induced microspore embryogenesis in coffee

A protocol for the induction of androgenesis and plant regeneration from C. arabica cv. Caturra isolated microspores in vitro using colchicine pretreatment has been developed. Microspores were mechanically isolated and then carefully purified. Before colchicine pretreatment, microspores were cultured in a semi-solid medium for further develop and regeneration. Different times of colchicine exposure as well as different concentrations were tested. The best androgenic response was found when microspores were precultured in 100 mg l^–1 colchicine for 48 h. The microspore developmental stages responsive to colchicine were late-uninucleated and early binucleated pollen. Flow cytometry and morphological analyses revealed that 95% of regenerated plants were dihaploids (2n=2x=22). However, some doubled dihaploid plants (2n=4x=44) were also obtained, suggesting that not only androgenic induction but also chromosome duplication could be expected as result of colchicine exposure of coffee microspores. This report represents a new approach in the coffee pollen culture, as well as a major step forward to the utilization of haploid technology in coffee breeding.