Effect of 24-epibrassinolide on duration of sorrel (Rumex acetosa L.) cultivation in vitro

In this study there was used 24-epibrassinolide - plant steroid hormone, responsible for the physiological response of plants to various environmental stresses. The effect of 24-epibrassinolide on the improvement of the sustainability of regenerates during completion of growing and acclimatization and then its transfer to greenhouse conditions were studied. We investigated the possibility of a prolonged cultivation without changing the medium, as well as the survival of regenerates during acclimatization. For research, sorrel (Rumex acetosa L.) was introduced into the culture in vitro by using the MS medium, with the addition of 30 g/l of sucrose, 100 mg/l of mesoinozitol and 3 g/l of phytagel. We used standard methods of cultivation with modifications. Benzyladenine-6 and a-naphthaleneacetic acids were used as growth regulators. The optimum ratio of growth regulators for callus formation, gemmagenesis and rhizogenesis was found. Culture medium % MS was used for completion of growing with the addition of 24-epibrassinolide at concentrations of 0.1, 0.5, and 1 mg/l. It was found that the 24-epibrassinolide at 0.5 mg/L increased the duration of regenerates' cultivation, without changing the culture medium, 2 times, as compared to control. Regenerates cultivated without adding 24-epibrassinolide in solid % MS medium died after 1-1.5 months of cultivation. For acclimatization, regenerates were transferred into sand and peat mixture (1:1) in greenhouse conditions with watering by 24-epibrassinolide solution in concentration of 0.5 mg/l. Watering was applied during a week. The cases of death of regenerates decreased 2 times as compared to control. It was found that it was possible to extend the period of cultivation, and reduce the degree of death of regenerates almost two-fold, provided 24-epibrassinolide was introduced in culture media, starting from the stage of regeneration, rooting and acclimatization at a concentration of 0.5 mg/l. The specimens grown with the addition of 24-epibrassinolide are characterized by lower level of development of the leafy part. Characteristically, this phenomenon is often observed at plant species in a stress situation. Root system reduction was not recorded. This phenomenon is supposed to be one of the reasons why the death of regenerates decreased in the period of acclimatization.

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