In vitro plant regeneration in Macroptilium atropurpureum, a legume with abroad symbiont range for nodulation

Macroptilium atropurpureum is a model legume with a broad symbiont range fo r nodulation. We have achieved the first in vitro plant regeneration of thi s species using cv. Siratro. Hypocotyl explants excised from dark-grown see dlings generated slimy, friable calli after three weeks' culture on B5 medi um containing 1-2 mg/l kinetin and 0.05 mg/l alpha-naphthaleneacetic acid. This was followed by the generation of green organogenic callus with shoot buds by subculturing the explants to hormone-free B5 medium 20 days after t he start of culture. The green organogenic calli with shoot buds were maint ained as organogenic callus by subculturing on the same medium, and shoots were elongated on hormone-free B5 medium. Elongated shoots were rooted on h alf-strength B5 medium. Most regenerated plants were morphologically normal , diploid and fertile, although tetraploid plants appeared at a low frequen cy (8%). (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.