Direct shoot regeneration and genetic fidelity analysis in finger millet using ISSR markers

Finger millet (Eleusine coracana (L.) Gaertn.), an economically important food crop is cultivated widely in the arid and semi-arid tropics of Africa and Asia. In the present study, an efficient micropropagation protocol has been established for finger millet genotypes CO 9, CO (Ra) 14 and GPU 28 using shoot apical meristems (SAMs). Shoot proliferation medium (SPM) containing Murashige and Skoog's (MS) medium amended with 3.0 mg/l 6-benzylaminopurine produced the highest shoot regeneration frequency (86.60%) with an average of 26.45 +/- 0.34 shoots per explant and 6.26 +/- 0.38 cm shoot length in CO 9. An increase in the number of shoots per explant was observed when SAMs were repeatedly sub-cultured in SPM at 2 weeks interval for 8 weeks. Rooting of the regenerated shoots was achieved in full-strength MS medium containing indole-3-acetic acid (IAA) or indole-3-butyric acid. Rooting medium containing 0.25 mg/l IAA exhibited highest rooting frequency (100%) with an average root length of 4.44 +/- 0.15 cm. In vitro rooted shoots transferred to the field conditions resulted in 100% survivability.Genetic fidelity of 3-month old mother plant and micropropagated plantlets was confirmed using 3'-anchored dinucleotide inter simple sequence repeats. A total of 115 amplicons generated for CO 9, CO (Ra) 14 and GPU 28 were monomorphic, revealing no variation among mother plant and micropropagated plantlets. Thus, SAMs could serve as a suitable explant for the mass multiplication of true-to-type plants and genetic transformation in finger millet.