An Efficient Culture System for Synchronization Control of Somatic Embryogenesis in Cotton (Gossypium hirsutum L.)

Low efficiency of somatic embryogenesis and asynchronous embryo development results in a lot of difficulties to physiological, biochemical, and molecular biological studies of the embryogenesis processes in cotton (Gossypium hirsutum L.). A simple and efficient method was developed to improve somatic embryogenesis frequency and synchronous development of mass somatic embryos from cultured cells of the cotton cultivar Coker 201. The embryonic calli obtained after several rounds of subculture were scattered in a liquid medium by shaking for 2 d and then resuspended in the same liquid medium after discarding the larger callus aggregates over a 30 mesh-size-sieve. The suspensions cultured for 14 d were filtered through a 50 mesh-size-sieve and the aggregates over the sieve were incubated for 21 d onto the surface of a Whatman filter paper that was placed on the solid medium containing 2.46 μmol L−1 indole-3-butyric acid (IBA) and 0.70 μmol L−1 kinetin. The amount of somatic embryos obtained by this system was 15.5-fold and 3-fold higher than that of suspension culture and solid culture without filter papers, respectively. About 70.2% for globular, 52.3% for torpedo-shaped, and 73.0% for cotyledonary embryos were obtained during the culture. The method combining suspension culture and solid culture (with filter paper) proved to be efficient for synchrony of somatic embryogenesis and mass embryo development.