**4. Some News with** *Cymbidium***,** *Dendrobium,* **and Others**

The most of results obtained with *Phalaenopsis* and *Oncidium* were similar to reported with other species of orchids of importance in floriculture, as *Cymbidium* and *Dendrobium* genera, such as the main PGRs used for IPR–PLBs. As example, the combination of cytokinin BA (5.0 mg L−1) and auxin NAA (2.5 mg L−1) were used to induce PLBs (20.55 PLB per primary protocorm) in *Cymbidium mastersii* protocorms [134]. Thin cell layers (TCL) from different types of tissues was a technique used to improve the production of PLBs in *Cymbidium* [135], *Dendrobium* [136,137], *Oncidium* [129], and *Phalaenopsis* [93].

In *Dendrobium*, a wide and complete study about molecular research was exhaustively carried out by [138], and considered especially the identification, classification and breeding of *Dendrobium*. Similarly, other study with micropropagation of *Dendrobium* was realized by [17] and concluded that PLBs were used as explants in 21.8% of studies, and together with nodal or nodal segments explants is one of the major method used for *Dendrobium* micropropagation.

Thidiazuron was also an important PGR for induction of PLBs in *Dendrobium* orchids, but the response to different cytokinins depends on genotype. In *Dendrobium aqueum*, only the cytokinin 2iP [*N*-6-(2-isopentyl) adenine] at 1.5 mg L−<sup>1</sup> proved it efficiency in production of PLBs (42.7 PLBs per explants) from callus, compared to other cytokinins BA, Kin and Zea, and cytokinin-like compound TDZ. These authors also observed that arginine at 25 mg L−<sup>1</sup> increased direct somatic embryogenesis, instead of callus derived PLBs [137]. Meta-Topolins, a natural aromatic type of cytokinin, were also reported used in induction and regeneration of PLBs in *D. nobile*, which combined with 0.5 mg L−<sup>1</sup> NAA resulted in best PLBs formation (92%) and shoots/explants (9.2) [139]. These same authors observed that addition of polyamines, such as spermidine and putrescine increased regeneration of shoots from PLBs and secondary PLB formation.

In our laboratory, PLBs of *Dendrobium* Hybrid 'H3', could be induced and proliferated in one-step, and obtained from in vitro shoots, using liquid MS1⁄2 medium with 1.0 mg L−<sup>1</sup> BA, and under agitation of 80 rpm (Figure 1D).
