EXOGENOUS CYTOKININS APPLICATION INDUCES CHANGES IN STOMATAL AND GLANDULAR TRICHOMES PARAMETERS IN ROSEMARY PLANTS REGENERATED IN VITRO

Abstract

Rosemary (Rosmarinus officinalis L.) is a native Mediterranean herb, used to typically prevent oxidation of fats and oils in foods and cosmetics. Rosemary represents an effective source of natural antioxidants with analgesic, diuretic, digestive and anti-inflammatory effects. This study is carried out to properly evaluate if exogenous cytokinin applications typically led to hyperhydration symptoms or any histological variability in stomatal density, stomatal distribution, glandular trichomes density and size of leaf epidermis. The colloidal technique was used for observation and measurement of leaf epidermis characters. The plantlets during in vitro culture were developed on MS media and two different PGRs ratios (BAP) / auxin (NAA) were tested: (i) 1 mg l-1 / 0.1 mg l-1 (ii) 2 mg l-1 / 0.1 mg l-1. In vitro leaves of both categories were taken for analyses 4 weeks after the first subculture and were compared with in vivo ones. The study showed that in vivo plantlets have hypostomatic leaves, meanwhile, in vitro plantlets of both categories consist of amphistomatic leaves. In all cases, there are observed anisocytic stomata. In vitro leaves have a higher stomatal density, value which is increased in higher concentrations of BAP and thus transpiration rates are affected. In vitro specimens show about 3 times higher trichomes density in comparison with in vivo ones, but their diameter is about 2 times lower. Glandular trichomes size and density are affected by BAP concentration in nutrient media. These results convincingly show that in vitro culture can be used successfully to improve secondary metabolites production by intentionally altering the growing physical and chemical conditions.