The
high regenerative capacity of plants is a crucial feature of their life strategy.
It is an essential part of the mechanisms that both allow these sessile organisms
to repair injury caused by pathogens, herbivores and abiotic factors and to
undergo rapid vegetative reproduction, so allowing them to dominate in particular
environmental niches. Furthermore, various forms of natural regeneration contribute
to techniques that are widely used in plant propagation and plant breeding. The
biological nature of plant regeneration has been studied since the very
beginnings of plant physiology as a science. Research on regeneration of intact
plants in vivo was conducted by Bohumil Ne ˇmec, and early studies of in vitro regeneration
in plant tissue cultures were carried out by Gottlieb Haberlandt. At this stage,
however, suggestions that somatic plant cells possessed a regeneration “totipotency”
were in practice often not acknowledged. Nevertheless, real experiments
demonstrated that the regenerative ability of particular cells and tissues is clearly
determined by the specific interplay of both genetic (or epigenetic) and physiological
factors. This makes some systems “nonresponsive” to the standard regeneration
procedures.
This regenerative recalcitrancy hampers both the routine vegetative
propagation of various plant species and the construction of genetically modified
crops. This chapter addresses the basic historical background of studies on plant
regeneration and discusses both the results and ideas acquired by means of classical
anatomical and morphological studies in the light of our current state of information
obtained using modern molecular techniques. The present knowledge of plant
regeneration is also viewed in the light of studies of structure and function of
the “stem cell niches” of multicellular organisms, examining their role in the ontogenesis
of intact plants and in the processes of embryogenesis and organogenesis in
vitro. With reference to other chapters in this book, the role of genetics for the
realisation of these processes as well as the role of various regulatory
factors, of both exogenous and endogenous nature – especially phytohormones –
is also examined. The importance to classify regenerative processes
unambiguously using exact terminology (in the context of the allied field of
regenerative medicine) as a prerequisite for the formation and validation of
appropriate working hypotheses is discussed. Finally, this chapter summarises
the main problems of current research on regenerative processes in plants and
outlines possible directions for solving problems of recalcitrant materials in
the context of their use for application.
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