MEDIUM COMPOSITION FOR IN VITRO MID-TERM STORAGE OF SOLANUM HABROCHAITES TEST-TUBE PLANTS

Abstract

Purpose. To investigate effects of osmotically active substances on the growth and development of isolated microcuttings of the wild tomato species S. habrochaites Knapp & Spooner and to determine an optimal composition of nutrient medium for their mid-term storage in vitro. Methods. General scientific, laboratory, biotechnological, measuring, statistical. Results. Possibilities of subcultivation-free storage of S. habrochaites (line BK-78) microcuttings in Murashige & Skug medium with different concentrations of sucrose (30, 60, 90 and 120 g/L), agar-agar (6, 9, 12 and 15 g/l) and sorbitol (0, 20, 40 and 60 g/L) for 30 (control), 90, 180 and 270 days under standard cultivation conditions were researched. The survivability, height, number of leaves, and root length in regenerants on different modifications of the medium were determined. There was an inversely proportional relationship between the percentage of viable regenerants and the time of in vitro storage without subcultivation on all variants of the medium. The maximum survivability of explants was achieved on the medium supplemented with 60 g/L of sorbitol (100.0 – 66.7% depending on the storage period), the minimum - on the medium containing 120 g/L of sucrose (40.0 – 22.5% ). A significant effect of the medium composition on the plant growth intensity was observed in the variants with 20, 40, or 60 g/L of sorbitol and 90 or 120 g/L of sucrose. Sorbitol-containing media also caused a 2- to 7.5-fold decrease in the mean height of regenerants and a 2.4- to 2.5-fold decrease in the number of leaves compared to the control. The root length of test-tube plants did not depend on the medium composition, except for the variants with 60 g/L of sorbitol and 120 g/L of sucrose. On media with increased agar-agar concentrations, the rate of explants development did not decrease, so these media are unsuitable for mid-term storage of in vitro collections. Conclusions. Among the studied medium modifications, the nutrient medium MS supplemented with 60 g/L of sorbitol turned out to be the most effective formulation for slow growth and mid-term storage of S. habrochaites regenerants, as it allows 66.7% of viable explants to be preserved for 270 days. However, through the lens of hyperhydration of test-tube plants, further optimization of in vitro storage conditions for this species is needed.