Optimization of callus induction and plant regeneration from germinating seeds of apomictic Cenchrus ciliaris L. (Poaceae)

Abstract

A highly efficient plant regeneration system via somatic embryogenesis was developed using germinating seeds of Cenchrus ciliaris genotypes IG-3108, IG-727 and EC397537. We tested different media supplements effects on callus induction, somatic embryogenesis, shoot induction and root formation. Seeds were cultured on Murashige and Skoog (MS) medium supplemented with 3.5 - 5.5mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) for callus induction. Genotype IG-727 showed highest callus induction frequency (93%) at 5.5mg/l 2,4-D as compared to other genotypes. Hard and compact embryogenic calli were transferred on MS medium supplemented with 3.5- 5.5mg/l 2,4-D and 0.5 mg/l BAP for somatic embryogenesis. For plant regeneration and rooting, embryogenic calli were transferred onto MS medium supplemented with 2-3mg/l IAA and 1-2mg/l BAP with incubation at 250C under an alternative photoperiod scheme (16 h light/8h dark).The maximum shoot induction frequency (60%) and root induction frequency (48%) was observed in genotype IG-727 at MS+3mg/l IAA+2mg/l BAP and MS+3 mg/l IAA+1 mg/l BAP media combination, respectively. The plantlets were transplanted to pots, where they exhibited morphologically normal growth.