Precise knowledge of all aspects controlling plant tissue culture and in vitro plant regeneration is crucial for plant biotechnologists and their correlated industry, as there is increasing demand for this scientific knowledge, resulting in more productive and resilient plants in the field. However, the development and application of cell and tissue culture techniques are usually based on empirical studies, although some data-driven models are available. Overall, the success of plant tissue culture is dependent on several factors such as available nutrients, endogenous auxin synthesis, organic compounds, and environment conditions. In this review, the most important aspects are described one by one, with some practical recommendations based on basic research in plant physiology and sharing our practical experience from over 20 years of research in this field. The main aim is to help new plant biotechnologists and increase the impact of the plant tissue culture industry worldwide.

Secondary somatic embryogenesis has been postulated to occur during induction of peach palm somatic embryogenesis. In the present study this morphogenetic pathway is described and a protocol for the establishment of cycling cultures using a temporary immersion system (TIS) is presented. Zygotic embryos were used as explants, and induction of somatic embryogenesis and plantlet growth were compared in TIS and solid culture medium. Light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to describe in vitro morphogenesis and accompany morpho-histological alterations during culture. The development of secondary somatic embryos occurs early during the induction of primary somatic embryos. Secondary somatic embryos were observed to develop continually in culture, resulting in non-synchronized development of these somatic embryos. Using these somatic embryos as explants allowed development of cycling cultures. Somatic embryos had high embryogenic potential (65·8 ± 3·0 to 86·2 ± 5·0 %) over the period tested. The use of a TIS greatly improved the number of somatic embryos obtained, as well as subsequent plantlet growth. Histological analyses showed that starch accumulation precedes the development of somatic embryos, and that these cells presented high nucleus/cytoplasm ratios and high mitotic indices, as evidenced by DAPI staining. Morphological and SEM observations revealed clusters of somatic embryos on one part of the explants, while other parts grew further, resulting in callus tissue. A multicellular origin of the secondary somatic embryos is hypothesized. Cells in the vicinity of callus accumulated large amounts of phenolic substances in their vacuoles. TEM revealed that these cells are metabolically very active, with the presence of numerous mitochondria and Golgi apparatuses. Light microscopy and TEM of the embryogenic sector revealed cells with numerous amyloplasts, large nuclei and nucleoli, and numerous plasmodesmata. Plantlets were obtained and after 3 months in culture their growth was significantly better in TIS than on solid culture medium. However, during acclimatization the survival rate of TIS-grown plantlets was lower. The present study confirms the occurrence of secondary somatic embryos in peach palm and describes a feasible protocol for regeneration of peach palm in vitro. Further optimizations include the use of explants obtained from adult palms and improvement of somatic embryo conversion rates.

In recent years, plant tissue culture has become a crucial component of the modern bioeconomy. From a commercial perspective, plant micropropagation remains one of its most valuable applications. Plants exhibit remarkable developmental plasticity; however, many species still remain recalcitrant in tissue culture. While the term recalcitrant is commonly used to describe plants with poor in vitro regeneration capacity, from a biological point of view it suggests that the minimal culture requirements for this species were unmet. Despite evidence that the Skoog–Miller exogenous hormonal balance theory and Murashige–Skoog medium were species-limited in applicability, generations of plant biotechnologists applied these tools indiscriminately. This led to systemic propagation of ineffective protocols, publication of misleading standards, and a culture of scientific inertia—costing both time and resources. The field must now move beyond historical dogma toward data-driven, species-specific innovation based on multiple endogenous auxin biosynthesis pathways, epigenetic reprogramming of competent cells, and further modern biotechnologies that are evolving. In this short viewpoint, we describe possible solutions in plant biotechnology to significantly improve the effectiveness of it.

The Brazilian Atlantic Forest is a biodiversity hotspot, and bromeliads are omnipresent in this biome. This study was aimed at characterizing both morphological and histochemical aspects of Vriesea friburgensis var. paludosa L.B. Sm. seeds. The seeds are filiform with a brown seed coat and yellowish-colored plumose appendages. Seeds are typically 4.4 mm long, 0.5 mm wide, and 1000 seeds weigh 683.8 mg. The seed coat presents phenolic compounds. Starch represents the main reserve compound in the endosperm; however, it is also present in smaller amounts in the embryo. The embryo occupies one-third of the seed and has a zone of constriction in the hypocotyl-radicle axis. The results of this work will contribute to the overall biology of V. friburgensis var. paludosa , as well as its taxonomic delimitation.

We present a new extraction method for opal phytoliths, which has high potential to support qualitative analyses of the unaltered properties of single opal phytoliths. Opal phytoliths have to remain in their original solution or an equivalent to protect their amorphous (SiO₂ nH₂O) molecular structure. Fresh leaf material was heated in distilled water in a microwave oven for 3–4 hours, stirred and then strained through a plankton sieve (50-μm mesh). After purification, the plant tissue matrix was successfully degraded. Single opal phytoliths of Phragmites australis and Arundo donax as well as cell debris were isolated.