Interconversion between protocorm-like-bodies (PLBs) and rhizomes in Cymbidium

Rhizome explants of three temperate terrestrial Cymbidium species, C. sinense, C. ensifolium and C. kanran, produced protocorm-like-bodies (PLBs) by the addition of 10mg/l 6-benzylaminopurine (BA). PLB explants of Cymbidium Melody Fair 'Marilyn Monroe', a hybrid of tropical species, induced rhizomes under shaded and continuous dark conditions, and the conversion was promoted by the supplement of 0.1 and 1mg/l a-naphthaleneacetic acid (NAA). The structure of the induced PLBs and rhizomes was very similar to that of the true PLBs and rhizomes, respectively, except for negative geotropism and less starch accumulation in the induced rhizomes. These results indicate that the interconversion between rhizome and PLB is possible in Cymbidium species and this organogenesis may be regulated by auxins and cytokinins.