The importance of applied light quality on the process of shoot organogenesis and production of phenolics and carbohydrates in Lachenalia sp. cultures in vitro

Light may be particularly important for in vitro plant morphogenesis due to its effects on primary and secondary plant metabolism (sugars and phenolics). This is the first report on the formation of Lachenalia adventitious shoots (caulogenesis) in relation to the content of endogenous phenolic compounds and carbohydrates in in vitro cultures exposed to diverse light conditions. The cultures were established from microshoot explants cultivated on Murashige and Skoog medium (3% sucrose, benzylaminopurine 2.5 μM, naphthalene acetic acid 0.5 μM). Total soluble phenolics, free and conjugated phenolic acids (cinnamic, p-coumaric, caffeic, ferulic, sinapic, chlorogenic), soluble carbohydrates and starch content were estimated in adventitious shoots of lachenalia 'Rupert' and 'Ronina' developed under white, blue, red light and in darkness. White and blue light stimulated the formation of adventitious shoots and buds which had also higher total phenolics content than those formed under red light and in darkness. Red light limited the process of organogenesis of lachenalia 'Ronina'. Caffeic acid was the most abundant phenolic acid, particularly in the shoots grown under blue and white light. Low concentration of endogenous ferulic acid accompanied the formation of adventitious roots. Red light and darkness caused elongation of lachenalia shoots, which also contained more glucose or fructose than those grown under blue and white light.