GRAPEVINE HABITUATION: UNDERSTANDING OF FACTORS THAT ONTRIBUTE TO SOMACLONAL VARIATION AND NEOPLASTIC TRANSFORMATION
I. Baumgartnerová, V. Repka
Slovak Agricultural Research Center – Institute for Viticulture and Enology, Matúškova 25, SK-831 01 Bratislava, Slovak Republic
A type of heritable cellular change, known as habituation, occurs spontaneously in plant tissue and cell culture. It is the acquired ability of a population of cells to grow and divide independently of exogenously supplied growth regulators. An imbalance in phytohormones in the media, particularly auxins and cytokinins, is an important source of stress and has been linked to hyperhydricity, somaclonal variation, recalcitrance and habituation. All of these abnormalities are potentially very costly to the plant breeding industry. Moreover, habituation as a tumorous and/or neoplastic transformation state that is interchangeable with a normal state in plant cell. This requires a better understanding of factors that contribute to these phenomena. Here we used a computational prediction method based on the known protein structural interactions to analyze grapevine large-scale protein-protein interaction rules within and among complete genomes such as yeast, fly, worm, Arabidopsis, and human and their HTP (high-throughput method) maps. These studies may help to elucidate the molecular mechanisms of neoplastic phenomena in plants and perhaps in animals.
We found fundamental differences among eukaryotic interactomes. We confirmed that all the predicted protein family interactomes (the full set of protein family interactions within a proteome) of 6 species are scale-free networks, and they share a small core network comprising 16 protein families related to indispensable cellular functions involved predominantly in the pathogenesis, apoptosis and plant tumorigenesis, as well. Molecular evidence is presented that suggests that grapevine cells that have become habituated for one or more essential factors results from heritable alterations in the pattern of gene expression and that it can, therefore, be used as a model for study of cell differentiation. Moreover, the overall significance of these findings to the plant and in a some instantion also the animal tumor problem is particularly discussed.