Regeneration of Proso Millet from Embryogenic Calli Derived from Various Plant Parts1

Abstract

Totipotency in cereal tissue cultures is often lost soon after callus initiation. Work by others with embryogenic cultures derived from various plant parts suggests that long term totipotent cultures can be obtained for some cereals and grasses. Long term totipotent tissue cultures of proso millet (Panicum miliaceum L.) which readily regenerated normal fertile plants were sought.Calli were initiated from immature embryos, mature seeds, mesocotyls, and leaf and stem segments cultured on Linsmaier and Skoog medium (L and S), 4% sucrose, 1% agar, and variable levels of 2,4‐D or 2,4,5‐T. For seeds, most callus was initiated on 1 mg/1 2,4,5‐T. Less callus was initiated by dark‐cultured seeds than by light grown seeds on 2,4‐D. Only dark‐grown seeds and immature embryos produced embryogenic callus on the first (initiation) passage. In light grown secondary callus, embryogenic and nonembryogenic calli had similar growth during a 6 week culture period. After 24 weeks in culture, 32% of embryogenic calli formed shoots as compared with 2% of non‐embryogenic calli cultured on no auxin.