Induction and growth of callus from immature inflorescences of “Zebra” bermudagrass as affected by casein hydrolysate and 2,4-D concentration

Abstract

Regeneration of grass plants through tissue culture is affected by many factors including genotype and type and concentration of medium components, particularly growth regulators. Objectives of this research were to characterize differentiation and growth of callus from immature inflorescence-explants of a variegated bermudagrass,Cynodon dactylon (L.) Pers. cv. “Zebra”, and to assess the effects of casein hydrolysate (CH) and 2,4-dichlorophenoxyacetic acid (2,4-D) concentrations on development of total callus mass and the embryogenic (E) portion. Immature inflorescences about 6 mm in length were inoculated in petri dishes containing modified Murashige and Skoog (MS) agar medium. Two levels of CH (0, 200 mg L−1) and four 2,4-D concentrations (1,3,5,7 mg L−1) in subplots were tested. Regeneration of 57 plants via somatic embryogenesis was achieved. Both fresh callus weight and E callus, expressed as a percentage of total callus, were significantly affected by CH and 2,4-D treatments. Maximum callus fresh weight and E callus concentration were attained in medium with 3 mg L−1 2,4-D. Addition of CH to the medium increased fresh weight and E callus within each level of 2,4-D, but not to the same extent as indicated by a significant (P<.01) 2,4-D X CH interaction. Presence of CH and 3 mg L−1 of 2,4-D maximized both fresh weight and percentage of E callus.