Phenolic compounds and carbohydrates in relation to bulb formation in Lachenalia 'Ronina' and 'Rupert' in vitro cultures under different lighting environments

The total soluble phenolic content, free and conjugated phenolic acids (cinnamic, p-coumaric, caffeic, ferulic, sinapic, chlorogenic), soluble carbohydrates and starch content were studied for the first time during the bulb formation in lachenalia (Lachenalia) in vitro adventitious shoot cultures of two cultivars which varied in their bulbing ability. Shoots of 'Rupert' and 'Ronina' were cultivated on the Murashige and Skoog (1962) medium with the addition of 3% sucrose and growth substances BA (2.5 mu M) and NAA (0.5 mu M) under different lighting environments (white, blue, red light and darkness). Lachenalia 'Ronina' formed most adventitious bulbs in darkness, whereas 'Rupert' produced them in all lighting environments. The results show a diversity of phenolic compounds in the storage organs of lachenalia cultivated in different lighting environments in terms of quality and quantity. In white and blue light or darkness, the total production of soluble phenolic compounds in cultures of investigated cultivars, varied from 1.1 to 2.0 mg/g d.w. and it was higher than in lachenalia exposed to red light (0.5 mg/g d.w.). Most of the examined conjugated phenolic acids occurred in bulbs at a higher concentration in the white and blue light, in comparison to the red light or in the dark. No, or only low concentration of chlorogenic acid was detected in scales of newly formed lachenalia bulbs. Bulbs of lachenalia 'Ronina' contained more soluble sugars, whereas bulbs of 'Rupert' contained more starch. (C) 2015 Elsevier B.V. All rights reserved.