Chromosome Duplication of Brachiaria decumbens Grass Using Colchicine

Abstract

Brachiaria decumbens is one of important tropical forage grasses. This grass has eXceptional adaptation to acidic soils, vigorous growth, ease of establishment, and good forage value throughout the year, but it is susceptible to spittlebugs pest. Breeding and improvement of forage grasses can be approached through cytological and genetic investigations. These research can contribute fundamental information that can be applied to the breeding of grasses. This research was aimed to optimize chromosome duplication of tetraploid B. decumbens (2n=47=36) grass using colchicine. 87plant of immature inflorescences were isolated and cultured in MS medium supplemented with 4 mg/L 2,4D and 0.2 mg/k kinetin for 4 weeks. The embryogenic calli were then transferred to regeneration medium MS supplemented with 4mg/l kinetin. Basal segment of the planlets then were immersed with a range of colchicine concentration (0.01%, 0.01%, and 0.1%) for 24 and 42 hours. After that, the buds were again placed in an MS medium without colchicine for regrowth. The chromosome number were confirmed by cytological analysis of root tips. The treatment of 0.1% colchicine for 42 hours can induce ploidy increase up to 11%. There was an increase in the rate of ploidy related to the increase in colchicine concentration.