ЧАСТНЫЕ И ОБЩИЕ КРИТИЧЕСКИЕ ПЕРИОДЫ В ОНТОГЕНЕЗЕ ЦВЕТКОВЫХ РАСТЕНИЙ

Abstract

Ontogenesis as the single process of formation and development of an individual with all specific organs remains to this day the most complex fundamental problem of the biology of the development of various organisms, including flowering plants. A separate place in solving this problem is occupied by the development of the concept of critical periods in the ontogenesis of an individual. The promising methodological approach to the development of this concept is the distinguishing both particular and general critical periods in ontogenesis. In this review based on the literature and own data the justification for the allocation of such critical periods in the ontogenesis of flowering plants is considered. The analysis of studies, the results of which can be associated with the identification of particular critical periods in plant ontogenesis at the cellular, tissue and organ levels based on criteria: (1) sensitivity of cells, tissues and organs to the action of external stress factors; (2) structural and functional rearrangements of the developing organ. The general periods critical for the whole individual are studied from the perspective of the conjugacy of organ-forming processes in plant ontogenesis, in particular the stages of organogenesis and their corresponding phenological phases. A special place is occupied by studies of critical periods common to the whole organism that occur during embryogenesis - the earliest stage of ontogenesis, when the whole organism is represented by the embryo. The criteria available in the literature for the identification of critical stages of embryogenesis are analyzed: (1) hypersensitivity of the embryo to external and internal adverse effects; (2) change of the structural and functional characteristics of the embryo and the surrounding seed tissues; (3) the autonomy of an immature embryo capable of completing embryogenesis outside the maternal organism (fetus, seed), with the formation of a normal plant; (4) the possibility of switching the embryo development program to alternative pathways.