Influence of explant type and variety of Linum usitatissimum L. convar. elongatum on the intensity of callus formation and organogenesis in vitro

Purpose. To determine the dependence of the intensity of callus formation and organogenesis of Linum usitatissimum L. convar. elongatum in vitro on explant type and variety in order to optimize the cultivation protocol. Methods. For induction of callus formation and organogenesis, hypocotyls, cotyledons, leaves, immature embryos and anthers of flax varieties ‘Hlinum’, ‘Esman’, ‘Hladiator’, ‘Hlobus’ and ‘Charivnyi’ grown on Murashige and Skoog medium were treated with 0.05 mg/l 1­naphthylacetic acid and 1.0 mg/l 6­benzylaminopurine at a photoperiod of 16 h, light intensity 2500 lux, relative humidity 60–80% and air temperature 22–24 °C. Empirical data were interpreted using arithmetic mean, error of the sample mean, coefficient of variation, least significant difference and rank order. Results. The intensity of callus formation and organogenesis in the analysed varieties depended on the object of study, i.e. the genotype of the variety and the type of explant. The frequency of callus formation ranged from 9.4 (anthers of variety ‘Esman’) to 99.4% (leaf explants of variety ‘Hlinum’), the weight of callus – from 0.18 (anthers of variety ‘Esman’) to 3.18 g (anthers of variety ‘Hlobus’), the frequency of organogenesis – from 7.4 (anthers of variety ‘Esman’) to 97.3% (hypocotyls of variety ‘Hlinum’), number of shoots – from 0.6 (anthers of variety ‘Hladiator’ and immature embryos of variety ‘Hlobus’) to 4.0 (hypocotyls of variety ‘Hlinum’), height of shoots – from 0.34 (anthers of variety ‘Esman’) to 1.63 cm (anthers of variety ‘Hlobus’). Conclusions. Plants of all the varieties studied are capable of effective callus formation and organogenesis in vitro in the presence of phytohormones of exogenous origin. Certain types of explants (hypocotyls, cotyledons, leaves) respond stably to exogenous growth regulators that induce callus formation, whereas others, such as anthers, have a specific response that is largely determined by cultivar characteristics. To obtain diploid somaclones, it is optimal to use hypocotyls of varieties ‘Hlinum’ and ‘Charivnyi’, to obtain haploid regenerants – immature embryos and anthers of varieties ‘Hlobus’ and ‘Hladiator’, which ensures the highest reproduction rate of cultural plant objects.