Chromosome duplication in Brachiaria (A. Rich.) Stapf allows intraspecific crosses

Brachiaria decumbens cv. Basilisk is the single most important forage grass used for pastures in the tropics.Breeding to produce improved cultivars has been impossible until now due to the lack of compatible sexual ecotypes. Thispaper reports the success of somatic chromosome duplication of sexually reproducing diploid plants of B. decumbens and ofa diploid hybrid between B. decumbens and B. brizantha, which should allow intraspecific crosses with natural apomictictetraploid accessions of either species. Polyploidization was induced in explants cultured in vitro on a medium supplementedwith colchicine at 0.01% for 48 hours, transferred to the same medium without colchicine until shoot regeneration occurred.Five sexual tetraploid plants (3.9% of plants recovered) were obtained. Crosses with apomictic cultivars recovered 14 seeds.The novel sexual tetraploids generated were unique and represented a major breakthrough in breeding B. decumbens toobtain superior hybrids.