Priming biotic factors for optimal protocorm-like body and callus induction in hybrid Cymbidium (Orchidaceae), and assessment of cytogenetic stability in regenerated plantlets

Protocorm-like bodies (PLBs) and callus were induced in epiphytic hybrid Cymbidium Twilight Moon ‘Day Light’, where induction capacity was strongly explant dependent. Following the use of various explant sources (PLB, leaf tip or base, root tip or base, cell and tissue ‘suspension’), highest PLB formation and callus induction occurred when we used whole PLBs, PLB segments or PLB transverse thin cell layers (tTCLs) or longitudinal TCLs (lTCLs). Plantlet growth and photosynthetic state from whole or bisected PLBs, as well as from tTCLs were not significantly different, after analysis of chlorophyll content. However plantlets generated from lTCLs showed lower values for growth and photosynthetic parameters. All resultant plants were shown to be cytogenetically identical using RAPD and mtDNA analysis despite cytological variation and endopolyploidy occuring between different plant parts. Acclimatization and survival rate was shown to be 100% in the generated plants.