The influence of RL (660 nm) and BL (450 nm) on the processes of callusogenesis and morphogenesis in vitro of tomato varieties of contrary precocity

Aim. To study the effect of RL (660 nm) and BL (450 nm) photoirradiation on the growth and morphogenetic reactions of callus of different origin of two tomato varieties contrasting in precocity. Methods. Two tomato varieties differing in growth type and precocity – ACE 55 VF and Kremenchutskyi – were used as plant material. Primary callus was obtained through the stage of aseptic seedlings, and three types of organs were used as explants: hypocotyl segments, cotyledon leaves, and apical parts of roots. Callus was grown on basal medium MS + 5 mg/l 2.4 D, in the dark at +26°C. The photoactivation with RL (660 nm) and BL (450 nm) was performed using Korobov LEDs. The frequency of callus proliferation, growth and morphogenetic reactions of the callus culture in vitro were analysed. Results. It was found that hypocotyl segments and cotyledon leaves of both studied varieties are more effective explants for obtaining primary callus. The ACE 55 VF variety, characterised by indeterminate growth type, forms mature callus tissue more efficiently than the determinate Kremenchutskyi variety. The photoexposure with RL (660 nm) stimulates the growth response of callus of ACE 55 VF variety. It is shown that irradiation with RL and especially BL activates the manifestation of morphogenetic reactions in callus of both varieties. Conclusions. To implement different pathways of morphogenesis in vitro, it is necessary to take into account the type of growth in vivo. Activation of the photoreceptor systems with RL and BL in the mature callus culture stimulates the processes of morphogenesis in vitro.