EFFECT OF EXOGENOUS DIKEGULAC ON IN VITRO SHOOT PROLIFERATION OF Sideritis raeseri L. � GREEK MOUNTAIN TEA SPECIES

Abstract

SUMMARYIn the present study, the effects of 8 dikegulac concentrations (0, 10, 25, 50, 100, 250, 500, 1500 μM) on in vitro shoot proliferation of the Greek mountain tea species "Sideritis raeseri L." were investigated. The culture medium used was the MS (Murashige and Skoog) supplemented with 30 g/l sucrose and 3 g/l Phytagel. After 5 weeks of culture in the proliferation medium, shoot number/explant was greatest (5.42) and slightly increased compared to the control (4.09 shoots/explant) with 25 μΜ dikegulac. However, no significant changes were monitored among treatments regarding shoot length (12.48-16.11 mm). The intermediate dikegulac concentrations (50-500 μΜ) substantially enhanced shoot multiplication percentage in relation to the control whereas the marginal ones (10 and 1500 μΜ) inhibited the explants' ability to proliferate considerably. The shoot multiplication percentage was 100% when 25, 100 or 500 μΜ dikegulac were applied. The percentage of callus formation at the base of the explants was 100% in all treatments except for the highest dikegulac concentration (1500 μΜ) in which a remarkable decrease by 33.33% was recorded. Vitrification was apparent in the majority of the explants including all treatments. In specific, this symptom was less extensive (16.67-18.18%) with low dikegulac concentrations (10 or 25 μΜ) whereas the percentage of explants showing hyperhydration was highest (63.64%) with 50 μΜ dikegulac. An efficient shoot proliferation protocol under in vitro conditions for the Greek mountain tea species -Sideritis raeseri L. was established using the plant growth regulator "dikegulac" as a promoting agent with potential applications in micropropagation.