Plant morphogenesis in vitro

Plant cells in vitro manifest a wider morphogenetic potential then in Nature due to the evolutionary determined capability of vascular plants for regeneration. We reviewed investigations on morphogenesis induction by exogenous regulators and by genetic transformation with the rol genes. Integrity disturbance and asymmetry creation are the main conditions required for the induction of regeneration programs. In in vitro experiments, these conditions are attained by a damaging treatment, explant extradition, diverse physical factors, primarily by suboptimal temperature, changes in irradiance, and the addition of physiologically active compounds (hormones or antitubulin drugs) to nutrient medium. Different morphogenetic scenarios are possible in dependence on the combination of internal and external factors determining initial conditions. This causes difficulties in the control of in vitro morphogenesis. We suggest to describe morphogenesis in terms of the set theory, basing on the concept of biological referents. Formalization performed allowed a detection of basic differences in the initial developmental stages under in vivo and in vitro conditions and a comparison between morphogenesis control in plants and vertebrates. As a result of this comparison, the concept of two languages responsible for morphogenesis of multicellular organisms was formulated. The first language is related to the events of differentiation, which are determined by a specificity of chromatin structural gene transcription. This may be formally presented as a chain of successive genotype states, each of which is mapped onto the phenotype traits. The second language has no phenotypic expression; it is related to the rules of information reproducing and storage. In this context, information is considered as a basic DNA structure of the individual organism and specific chromatin state inactive in transcription. Formal diagrams of plant ontogeny are interpreted from the positions of molecular mechanisms of morphogenesis control. The scheme of the genotype states corresponding to various levels of differentiation is presented.