Diversification of somaclonal variations in different crops by using inducing factors of endo- and exogenous origin (genotype, explant, viral infections - phytoviruses, morpho-physiological indices, nutrient media with various hormonal balances, conditions and terms of in vitro culture, gamma irradiation). The in vitro culture method is based on plant tissues culture from different types of explants: mature embryos (durum and common wheat), immature embryos (durum wheat, corn and tomatoes), aseptic leaf (durum and common wheat, triticale), leaf segments (tomatoes, potatoes), internodes (potatoes), sepals (tomatoes); androgenesis (barley) and gynogenesis (durum and common wheat). Virusologic methods for diagnosing viral agents include the method of mechanical inoculation of experimental plants, the negative contrast electron microscopic techniques. The evaluation of somaclonal variations was performed by biometric methods according to culture-specific guidelines UPOV and biochemical - electrophoretic analyzes of reserve proteins and peroxidases in minitubers of potato somaclones. In order to assess the role of endo- and exogenous inducing factors and their interaction in the source of variation for in vitro regeneration indices and somaclones quantitative traits, multifactorial analyzes of variance (ANOVA) were applied. Procedures for obtaining somaclones and androclones in different plants species were developed, as well as the peculiarities of cell proliferation by induction of callus tissue, somatic or microspore embryogenesis and in vitro regeneration of plants were elucidated. The use of phytopathogenic viruses in complex with in vitro culture led to the diversification of somaclonal variations that were quantified by morpho-physiological, biometric and biochemical indices. It has been shown that virus-free somaclones, which show increased resistance to Potato Virus Y (PVY), can be obtained through callus cultures initiated from potato plants infected with PVY. Morphological variations were observed in the somaclones of tomatoes (modifications in stem, inflorescence and fruit) and wheat (bifurcation of the spike and placement of leaves unilaterally on the stem), as well as in the double haploids of androgenic origin of barley (lateral spikelet, compaction of spikelets). The concept of modulation of somaclonal variations has been scientifically substantiated, in the sense of diversifying the variability induced by in vitro cultures, in case of directed exploration of inducing factors of endo- and exogenous origin.