Improved plant regeneration from barley callus cultures by increased copper levels

Abstract

Incorporation of cupric sulfate into callus induction, maintenance, and regeneration media significantly enhanced plant regeneration from callus cultures of barley (Hordeum vulgare L.) immature embryos. Embryos from the cultivars ‘Hector’ and ‘Excel’ were cultured on MS medium containing 0, 0.1 (MS level), 0.5, 1.0, 5.0, 10.0, 50.0, or 100.0 μM cupric sulfate. Plants were regenerated beginning at 8 weeks and continuing through 36 weeks. For Hector, medium containing 50 μM copper regenerated significantly more plants than any other medium, with an average of 17 plants per embryo. In comparison, medium with MS copper levels (0.1 μM) regenerated only 5 plants per embryo. For Excel, medium containing 5.0 μM copper was the best, regenerating 1.4 plants per embryo. No Excel regenerants were obtained on medium with MS copper levels. Increased copper levels also increased the percentage of embryos that regenerated at least one plant, in both cultivars. The results indicate that MS copper levels are not optimized for barley callus cultures, and that improved plant regeneration can be obtained at higher copper concentrations.