Phalaenopsis is one of the most popular orchid genera, exhibiting a variety of flower morphologies. Ploidy level was a factor influencing the success of Phalaenopsis crossbreeding. This research aimed to determine the ploidy level by flow cytometry and correlation with morphological characteristics on six hybrid cultivars of Phalaenopsis (1702, 1819, 1981, 3903, 3904, and 3908). Flow cytometry analysis on young leaves and root tip cells was also carried out on P. amabilis, P. amboinensis, and P. schilleriana. Research results showed multiple peaks of fluorescence appeared on the flow cytometry histogram. The young leaves and root tip cells show the distribution of cells into different ploidy levels and indicate mixoploid and endopolyploid conditions of the cells in both leaves and root samples. This complexity makes it challenging to determine the ploidy level of each cultivar and the correlation between morphological characteristics and ploidy level, even though the weak positive correlation was prominent between flower numbers and genome size. These findings serve as foundational data on the cytogenetic background of the cultivars for orchid breeders in crossbreeding, selection of haploid plants, mutation analysis, and variety consistency monitoring.
Phalaenopsis, DNA contents, flow cytometry, genome size, mixoploid, ploidy level, morphological characterization
Flow cytometry analysis revealed a mixoploid condition; however, the ploidy level of hybrid cultivars and species may be triploid or tetraploid. A weak positive correlation between flower number and genome size was apparent, but no definitive morphological indicators for ploidy levels emerged.