Effects of Physiological Status of Parent Plants and Culture Medium Composition on the Anther Culture of Sorghum

Anthers at various maturation stages were collected from seven genotypes of Sorghum bicolor, and cultured on MS medium supplemented with 3 mg L−1 2,4-D and 2.0 mg L−1 kinetin. The rate of callus induction was high in young anthers, and decreased with maturation of the anther. Young anthers were collected from the plants grown in the greenhouse (greenhouse anthers), in the field (field anthers), and in the chambers kept at 20, 25 or 30 °C. Then they were cultured on MS medium containing 2.0 mg L−1 kinetin, 1.0 mg L−1 IAA and 2.5 mg L−1 2,4-D, on which the rate of callus induction was the highest. The average callus-induction percentage was 6.4% in the field anthers, and 3.7% in the greenhouse anthers. Callus induction was low in the anthers collected from the plants grown at 30° C. Among the genotypes examined, TX403 produced calli at the highest frequency. The rate of plant regeneration from anther-calli was the highest on the medium containing 2.5 mg L−1 kinetin and 3.0 mg L−1 IAA. The regeneration rate of green plantlets on this medium was 27% on the average, and was 46.2 and 28.6% in PP290 and TX403, respectively. The chromosome number in root-tip cells was unstable, but was 20 in most of the regenerated plantlets