Colchicine, an efficient genome-doubling agent for maize (Zea mays L.) microspores cultured in anthero

The construction of maize genotypes with high haploid induction capacity made it possible to study the effect of colchicine on maize androgenesis in vitro. Anther cultures of three hybrids were treated with 0.02% and 0.03% colchicine for 3 days at the beginning of microspore induction. Colchicine added to the induction medium had no negative influence on the androgenic responses (anther induction, induction of structures of microspore origin and their regeneration ability) of the genotypes examined. However, significantly higher fertility was observed in plants originating from colchicine-treated microspores, especially at 0.03%. Cytological examinations showed that colchicine treatment before the first microspore division efficiently arrested mitosis and resulted in homozygous doubled-haploid microspores. Under the experimental conditions, the antimitotic drug had no later effect on the division symmetry of the microspore nucleus, and unequal divisions remained dominant. Callus formation from the induced microspores seemed to be more typical (ranging between 60–70%), but embryo frequency was increased by approximately 10%, especially at the higher colchicine concentration. These results suggest that the mechanism of colchicine action in premitotic maize microspores may differ from that previously observed in wheat. Received: 15 June 1998 / Revision received: 17 September 1998 / Accepted: 3 December 1998