Implication of growth at different light quality regimens on photosynthesis, leaf anatomy and volatile compound emission in two plant models: a fast-growing crop and a fast-growing tree.

The effect of different light quality on photosynthetic performance, leaf anatomy and isoprenoid emission was studied in two different plant systems: a fast-growing crop, tomato (Solanum lycopersicum L.), and a fast-growing tree, oriental plane (Platanus orientalis L.). Both species were subjected to three different light quality regimes: RGB, RB and white light (WL), considered as control. Plants were analyzed for growth, leaf anatomical traits, photosynthesis and emission of key volatile compounds, in order to evaluate the capacity of the two plant models to regulate gas exchanges and optimize functional metabolites and biomass production under different radiation quality. In both species, the growth under RGB and RB light induced a more compact plant size, i.e. the reduction in plant height, biomass and leaf area. In tomato, the RGB and RB growth determined higher values of CO2 assimilation rate (A), stomatal (gs) and mesophyll (gm) conductance than WL; the trend was similar in oriental plane, but only gs significantly increased under RB. The anatomical leaf traits were strongly affected by light quality: in tomato, leaf lamina thickness was significantly reduced in RGB and RB leaves compared to WL ones; in oriental plane the opposite trend was observed. In both species, RB leaves showed higher stomata size than WL and RGB leaves. Light quality also influenced photosynthesis-dependent volatile isoprenoids. In tomato, β-phellandrene was lower under RB and RGB compared to WL. However, RGB and RB treatments stimulated α-pinene, carene and α-terpinene emissions. In oriental planes the isoprene emission was reduced under RGB and more so under RB. Briefly, photosynthesis, leaf anatomy, biomass production, and volatile isoprenoid emission are affected by light quality differently in the two plant model. In both cases, light quality control may have important applications to modulate plant productivity and biosynthesis of useful biochemical compounds.