Development of Photochemical Activity in Chloroplast Membranes. II. Studies With a Mutant of Barley Grown Under Different Environments

Abstract

Chloroplast development in the barley mutant xantha-b¹², a nuclear gene mutant derived from Hordeum vulgare L. cv. Svalöfs Bonus, was profoundly influenced by the temperature and light intensity to which the plants were subjected during growth. Low temperatures and high light intensities retarded chloroplast development. By growing this mutant under different combinations of temperature and light intensity, seedlings were produced containing chloroplasts at different developmental stages. Measurements of photochemical activities of the isolated chloroplasts indicated a sequence for development of photochemical competence in chloroplast membranes very similar to that adduced from a study of several different barley mutants grown under a single environment. A photoreductive capacity is initially acquired but energy conservation sites only become fully functional at an advanced stage of membrane development.