The composition and function of thylakoid membranes from pea plants grown under white or green light with or without far‐red light

Abstract

Pea plants (Pisum sativum L. ev. Greenfeast) were grown for 2 to 3 weeks in while (˜ 50 μmol photons m−2 s−1; 400–700 nm) or green (˜ 30 μmol photons m−2 s −1 400–700 nm) light (16 h day/8 h night), with or without far‐red light. Supplementary far‐red light decreased leaf area and increased internodal length in both white and green light, demonstrating that phytochrome influenced leaf size and plant growth. However, there was no effect of far‐red light on chlorophyll a/chlorophyll b ratios, chlorophyll‐protein composition, the stoichiometry of electron transport complexes or photosynthetic function of isolated thylakoids. These results suggest that phytochrome is ineffective in modulating the composition and function of thylakoids in pea plants grown at low irradiance. One possible explanation of the ineffectiveness of phytochrome on thylakoids is discussed in terms of the drastic attenuation of red relative to far‐red light in green tissue.