High-frequency direct plant regeneration via multiple shoot induction in the apomictic forage grass Cenchrus ciliaris L.

Genetic improvement of the apomictic forage grass species Cenchrus ciliaris L. based on conventional breeding methods is difficult and time-consuming. However, in vitro genetic manipulation of such species would provide a promising approach. A rapid and high-frequency in vitro plant regeneration protocol is essential for successful application of transgenic technology. This study reports on such a rapid, high-frequency and genotype-independent plant regeneration protocol for C. ciliaris L. Using the multiple shoot induction approach, up to 20 shoots per explant could be induced from shoot tips cultured on MS (Murashige and Skoog) medium when supplemented with 3.0 mg L⁻¹ TDZ. Two cultivars (IGFRI-3108 and IGFRI-727) and three exotic germplasm accessions (EC-397670, EC397496, and EC397336) showed equivalent responses to the protocol. Shoot tips from 4-d-old in vitro grown seedlings were used as explants for multiple shoot induction. Regenerated shoots were cultured on MS medium supplemented with gibberellic acid (2.0 mg L⁻¹) for shoot elongation. The regenerated shoots were rooted on MS medium supplemented with indole-3-acetic acid (3.0 mg L⁻¹). When transferred to soil in pots, hardened plants displayed up to 85% survival under field conditions.