Cellular, Molecular, and Physiological Aspects of In Vitro Plant Regeneration

Abstract

Plants generally have the highest regenerative ability because they show a high degree of developmental plasticity. Although the basic principles of plant regeneration date back many years, understanding the cellular, molecular, and physiological mechanisms based on these principles is currently in progress. In addition to the significant effects of some factors such as medium components, phytohormones, explant type, and light on the regeneration ability of an explant, recent reports evidence the involvement of molecular signals in organogenesis and embryogenesis responses to explant wounding, induced plant cell death, and phytohormones interaction. However, some cellular behaviors such as the occurrence of somaclonal variations and abnormalities during the in vitro plant regeneration process may be associated with adverse effects on the efficacy of plant regeneration. A review of past studies suggests that, in some cases, regeneration in plants involves the reprogramming of distinct somatic cells, while in others, it is induced by the activation of relatively undifferentiated cells in somatic tissues. However, this review covers the most important factors involved in the process of plant regeneration and discusses the mechanisms by which plants monitor this process.

Keywords: abnormalities; in vitro regeneration; micropropagation; organogenesis; somatic embryogenesis.

Figure 1

Morphology of different stages during plant organogenesis in Nicotiana rustica. (A) Root regeneration from callus tissue. (B) Shooty callus. (C) Embryo regeneration from callus tissue. (D) Compact callus (E) Shoot regeneration from callus tissue (F) Shoot clumps regenerated from a friable callus.

Figure 2

Totipotency and pluripotency in plant regeneration.