Comparing in vitro plant regeneration ability of Oryza sativa L. cv. Fujisaka 5 and Brachiaria decumbens from embryogenic callus

Abstract

Abstract. Daud Z, Osman AS, Jelodar NB, Chan L-K. 2022. Comparing in vitro plant regeneration ability of Oryza sativa L. cv. Fujisaka 5 and Brachiaria decumbens from embryogenic callus. Cell Biol Dev 7: 20-27. The aim of this study was to compare the plant regeneration ability of Oryza sativa L. cv Fujisaka 5, a cold resistance japonica rice and Brachiaria decumbens Stapf, a tropical savanna grass, using embryogenic calli. The plant regeneration ability of both species has not been reported elsewhere. Friable calli were induced from the O. sativa Fujisaka 5 seeds on MS medium supplemented with 2.0 mgL^-1 2,4-D. While embryogenic calli were produced from B. decumbens seeds using a similar culture medium and remained embryogenic even after frequent subculturing. The friable calli of O. sativa Fujisaka 5 became embryogenic (88.2-97.7%) when they were subcultured onto MS medium containing 2,4-D and kinetin or BAP and NAA (0.5 - 1.0 mgL^-1) for four weeks. When the induced embryogenic calli (0.5 g) of both species were subcultured onto MS without plant growth regulators, plantlets were generated after one to two weeks with the formation of 2-3 plantlets for O. sativa Fujisaka 5 and 4-5 plantlets for B. decumbens per 0.5 g calli. The present study proved that plant regeneration of B. decumbens could be accomplished via direct somatic embryogenesis, which involved two stages: initiation of somatic embryos from germinating seeds on MS medium supplemented with 2.0 mgL^-1 2,4-D and plantlet regeneration achieved via transferring the somatic embryos onto MS medium without PGRs. Plantlets of O. sativa Fujisaka 5 were established via indirect somatic embryogenesis which involved three stages: induction of callus from germinating seeds on MS medium supplemented with 2.0 mgL^-1 2,4-D, followed by the production of somatic embryos using MS medium containing 0.5 - 1.0 mgL^-1 2,4-D and kinetin or BAP and NAA and finally plant regeneration by subculturing the somatic embryos onto MS medium without PGRs. These established plant regeneration protocols of O. sativa Fujisaka 5 and B. decumbens would be useful for future rice improvement research.