Moreover, as we did not sample all organs and structures (including roots, rhizomes and laminae but also meristems and differentiating tissues) for each of the species studied, we can by no means state that certain epitopes are absent in the plant.
For the 65-day seedlings, data were taken from 60 seedlings for the following parameters: percentage of seedlings with callus tissue, hairs on leaves and hairs on rhizome-like structures, and the number of PLBs/rhizome-like growths.
Moreover, the unique propagative structures of 65 and 145 DAC seedlings, rhizome-like structures and microshoots, respectively, were induced from leaf axils as normal seedling leaves became necrotic.
In this work, hairs of the older auxin-treated seedlings were numerous and randomly placed on the rhizome-like structures and fused, fleshy leaves.
This work characterized three auxin growth responses in S. plicata seedlings that have not been reported in orchids: (i) the inhibition of first leaf initiation and abnormal first leaf morphology; (ii) the promotion of trichome formation; and (iii) the induction of rhizome-like structures and microshoots at a specific stage in seedling development.
Emodin, (1, 3, 8-trihydroxy-6-methylan-thraquinone, molecular structure is Figure 1) a natural anthraquinone derivative found in the roots and rhizomes of numerous plants such as Polygonum multiflorum, rhubarb, Alose.
All of these plant structures, rhizomes, PLBs and microshoots, have been used successfully in propagation in S. plicata or other orchid species (Arditti 2008).
It multiplies through seeds and rhizomes [19].
However, plant roots and rhizomes were not damaged.
Identification of these structures as rhizomes was further supported by the fact that auxin application has been shown to induce rhizome formation from leaf axils of Cymbidium (Shimasaki and Uemoto 1990).
