In vitro and in vivo characterization of Cymbidium cultivars by isozyme analysis

Starch gel electrophoresis of six enzyme systems was carried out on twenty Cymbidium hybrid cultivars. Four systems gave consistent results and a total of 13 presumptive loci, eight of which were polymorphic, were identified. Comparisons of in vitro and in vivo sample sources showed that PLBs from in vitro sources could be used successfully for the characterization of cultivars. With aspartate amino-transferase (AAT), phosphoglucose isomerase (PGI) and malate dehydrogenase (MDH), the 20 cultivars sorted into 16 uniquely identified individuals and two pairs which were easily separated by including phosphoglucomutase (PGM). Isozymes did not detect any mericlonal variation due to culture in vitro. Controlled crosses showed simple inheritance for AAT-1 controlled by two alleles. We suggest the possibility of linkage of the 'a' allele in the PGM system to a lethal allele. There is enough enzymatically detectable genetic variation among Cymbidium cultivars and identification potential increases with the number of isozymes used.