Shoot Formation from Leaf Explants and Apical Meristems of «Peperomia obtusifolia» A. Dietr. : Stability of Ploidy Level in Their Subcultures

Leaf expiants of Peperomia obtusifolia were cultured on Murashige and Skoog basal medium (MS) with various growth substances in order to regenerate shoots. On MS basal medium associated with auxines (IAA or NAA) and kinetin, the expiants favoured green callus, many roots but scarce shoots. On MS supplemented with auxines and BAP, 30-40% of the expiants produced green callus and numerous shoots per explant, but no roots. The shoots, after 4-5 months, were removed from initial expiants and transferred separately onto MS basal medium or MS supplemented with IBA for their elongation and successive rooting. Histological studies showed that the callus was essentially associated with the spongy parenchyma cells near the vascular tissue from which shoots regenerated. The subcultures were obtained from leaf expiants or apical meristems from the previous generation (up to 5th -6th) with more numerous productive expiants and also more shoots per expiant in less time than the initial cultures. Chromosome numbers of root tip cells of the mother plant and of all in vitro plant generations remained constant: 2n = 22.