In vitro culture responses of Hordeum murinum and H. vulgare, and factors affecting on callus formation and growth

Successful tissue culture research and its practical application require a reliable culture procedure. During the tissue culture practices, the effects of genotype, medium composition and growth regulator (2,4-D) concentration on callus induction and growth were tested. A wild species of the genus Hordeum (Hordeum murinum), was tested beside the cultivated barley (Hordeum vulgare), for the study of genotypic variation in response to tissue culture. Matue seeds or immature embryos of both wild and cultivated barley species were used as---explants. Culture media contained MS macro- and micronutrients, or MSm (modified MS based salt), supplemented with 1.0 or 3.0 mg/l dichlorophenoxyacetic acid (2,4-D) as a growth regulator.
On both of the test media, seedlings grown from seeds of both wild and cultivated barley produced callus. Averaging across genotype, the number of calli induced was greater in cultivated than wild barley. MS based medium gave faster callus induction than MSm based medium, although the medium formulations showed no difference for callus induction in tested genotypes.
Comparisons across media revealed that callus growth in cultivated barley was greater on MS than MSm based medium. Furthermore, although little difference was observed in callus induction between the test concentrations of 2,4-D between two genotypes, calli obtained from cultivated barley grew faster in response to 3.0 than 1.0 mg/12,4-D on both media. Callus was also initiated from immature embryos of both test species on the medium containing MS based salts and 3 mg/l 2,4-D. Cultivated barley showed a higher efficiency of callus production (84.5%) than wild barley (77.7%). Also, calli derived .from both mature and immature embryos of cultivated barley showed prolonged growth, but the induced calli in wild barley ceased growth, turned brown and died after a few weeks.