Plant Regeneration from Tissue Cultures of Amaranthus Species
As one of the few genera of dicotyledonous plants which use the C4 pathway of photosynthetic carbon fixation, Amaranthus may be interesting both for its future potential as a crop plant and for studying the genetic regulation of the C4 photosynthetic pathway. Thus, we are attempting to develop systems for whole plant regeneration from tissue and cell cultures, and from protoplasts of Amaranthus spp. Amaranthus callus cultures can be initiated from hypocotyl segments prepared from aseptically germinated seeds by placing such segments on media containing Murashige and Skoog (MS) salts and vitamins, 3 or 10 mg/1 2,4-dichlorophenoxyacetic acid (2,4-D), and 0.05 mg/1 kinetin. MS media containing indoleacetic acid (IAA) or naphthaleneacetic acid (NAA) at concentrations up to 10 mg/1 are ineffective at producing a proliferating callus in the presence or absence of N6-benzyladenine (BA) or kinetin at concentrations up to 10 mg/1. The callus produced on cytokinin-containing media forms progressively more brown pigment and grows more slowly as the cytokinin concentration increases.