Increased gibberellin levels enhance light capture efficiency in tobacco plants and promote dry matter accumulation

Plants are constantly subjected to light variations in the environment, and plant hormones are one of the intermediaries between environmental signals and physiological responses. Among these responses, gibberellins (GAs) promote physiological changes that regulate plant growth and development patterns. Morphological changes, such as internode length and light absorbance maximization, are likely to induce plant performance increases leading to biomass accumulation. In this context, the hypothesis tested herein was that manipulation of GA levels can influence plant biomass accumulation by modifying the internode length and, consequently, light capture efficiency, with direct effects on plant biomass accumulation rates evaluated by unit leaf rate and growth analysis. For this, tobacco plants were cultivated in high- and low- irradiance environments under different gibberellic acid (GA 3 ) and paclobutrazol (PAC, a GA biosynthesis inhibitor) concentrations as a tool to manipulate the internode length and plant height. Dry matter accumulation was evaluated in response to light capture efficiency and interception, energy content and anatomical stem changes. The results obtained and supported by a principal component analysis indicate that GAs are capable of promoting phenotypic changes in plants grown in both high and low irradiance environments, and that they trigger responses related with biomass accumulation by maximizing light capture performance in response to internode length in tobacco plants. The data presented herein emphasize that GAs are essential in promoting growth and biomass accumulation, especially in low irradiance environments.