The data on various aspects of the use of cereals callus cultures in vitro as model systems for the study of the plant stress-resistance to abiotic factors are presented. The focus is on...

The use of in vitro callus cultures as experimental model systems allows us to get closer to understanding the patterns and features of morphogenesis in intact plants. In this regard, the problem of realizing the morphogenetic potential of callus cells due to their pluri- and totipotency properties is of great interest. To solve this problem, it is important to use the histological approach, which involves studying the structures of developing tissues, organs and organisms in their interactions and relationships. This review article analyzes data devoted to the study of the histological features of formed primary morphogenic calli (formation of morphogenetic centers and superficial meristematic zones), as well as the in vitro morphogenesis pathways in calli that lead to the formation of regenerants (de novo organogenesis and in vitro somatic embryogenesis). The terminology used is considered. Some questions for discussion are raised. The opinion is expressed that histological (structural) studies should be considered as a methodologic basis for further investigation of various morphogenetic scenarios in in vitro callus cultures, especially in economically valuable plants and for biotechnological purposes.

Callus is an integrated system formed both exogenously (as a result of proliferation of surface cells of different plant tissues) and endogenously (deep in tissues). Initially, callus consists of...

The formation of embryoids obtained in vitro both in the culture of anthers and in the culture of the immature embryos of spring soft wheat was analyzed using light microscopy and transmission...

The most important problem in studying plant calluses in vitro is the relationship between endogenous and exogenous factors that affect the formation of callus (“callus formation”) and their development in an induction medium (“callusogenesis”). Such an endogenous factor as the cytophysiological status of explants in vivo and of calluses in the dynamics of in vitro cultivation attracts the particular attention of the scientific community. In this review, considering the example of cereals, the literature and the authors’ own data on the identification of histological and hormonal features of initial callus cells in explants, immature embryos in vivo, and morphogenic calluses formed from them during in vitro development have been analyzed. The answers to some controversial questions related to the induction of morphogenetic competence and reprogramming of the development of initial callus cells presented in the literature are considered. The comparison of callus formation and callusogenesis in vitro with some similar events in vivo confirms the validity of the principle of universality of morphogenesis processes in vivo and in vitro (Batygina, 2014 and earlier). The prospects applying an integrated experimental system “embryo in vivo–callus in vitro” as a model for studying plant morphogenesis, one of the most complex biological phenomena, is discussed.