Competence and regulatory interactions during regeneration in plants

Abstract

The ability to regenerate is widely exploited by multitudes of organisms ranging from unicellular bacteria to multicellular plants for their propagation and repair. But the levels of competence for regeneration vary from species to species. While variety of living cells of a plant display regeneration ability, only a few set of cells maintain their stemness in mammals. This highly pliable nature of plant cells in-terms of regeneration can be attributed to their high developmental plasticity. De novo organ initiation can be relatively easily achieved in plants by proper hormonal regulations. Elevated levels of plant hormone auxin induces the formation of proliferating mass of pluripotent cells called callus, which predominantly express lateral root meristem markers and hence is having an identity similar to lateral root primordia. Organ formation can be induced from the callus by modulating the ratio of hormones. An alternative for de novo organogenesis is by the forced expression of plant specific transcription factors. The mechanisms by which plant cells attain competence for regeneration on hormonal treatment or forced expression remain largely elusive. Recent studies have provided some insight into how the epigenetic modifications in plants affect this competence. In this review we discuss the present understanding of regenerative biology in plants and scrutinize the future prospectives of this topic. While discussing about the regeneration in the sporophyte of angiosperms which is well studied, here we outline the regenerative biology of the gametophytic phase and discuss about various strategies of regeneration that have evolved in the domain of life so that a common consensus on the entire process of regeneration can be made.

PLETHORA Genes Control Regeneration by a Two-Step Mechanism

“…In the commonly used indirect shoot regeneration system, explants excised from differentiated plant tissues are induced to generate callus, a pluripotent regenerative mass of cells, by incubation on an auxin-rich callus inducing medium (CIM). Subsequently, de novo shoots can be regenerated from the callus upon incubation on shoot inducing medium (SIM) which contains high cytokinin to auxin ratio [2,6]. The process of callus formation is thought to be important for the acquisition of competence to form shoot meristems in the succeeding step [7,8].…”

“…This is a common hurdle to the understanding of the complete regeneration process in plants and in animals. Although many shoot meristem-expressed genes and hormone-related genes have been implicated in Arabidopsis shoot regeneration based on their mutant phenotypes [2,6,14], mechanisms underlying the acquisition of regeneration competence and completion of de novo shoot formation remain largely elusive.…”

“…In plants, the regeneration process is widely exploited for in vitro propagation of materials in horticulture. A wide variety of plant tissues (explants) is capable of regenerating an entire organism when supplemented with an appropriate culture medium [1,2]. In Arabidopsis, root and hypocotyl tissues are widely used sources for de novo organogenesis [3,4].…”

“…Regeneration is a common strategy adopted by both plants and animals with functions in tissue repair and propagation [1,2]. In plants, the regeneration process is widely exploited for in vitro propagation of materials in horticulture.…”

Plant regeneration: cellular origins and molecular mechanisms

“…Regeneration is a widely conserved physiological response in both animals and plants (Pulianmackal et al, 2014). What is collectively referred to as regeneration can range from the repair of a small amputation to the formation of new organs or individuals, and the mode of regeneration varies markedly among taxa (Birnbaum and Sánchez Alvarado, 2008).…”