Assessment of the electrochemical potential of thylakoid membranes in Hordeum vulgare L. seedlings of different ages under heat stress using the method of differential absorption spectroscopy

Abstract

Using the method of differential absorption spectroscopy and technology of the electrochromic shift of pigment absorption, the electrochemical potential on the thylakoid membrane and its components in the primary leaves of 4-, 7- and 11-day-old seedlings of Hordeum vulgare L. was studied. It was found that during the ontogenesis of the first leaf, the proton motive force decreased and the proportion of its electrical component increased. Exposure to elevated temperature (40°C for 3 h) decreased the magnitudes of the electrochemical potential, proton gradient, and thylakoid membrane conductivity for protons, and also increased the electrical potential on the thylakoid membrane in young 4-day-old seedlings. In 7-day-old leaves, which have a fully formed photosynthetic apparatus, no significant changes in the formation of the electrochemical potential on the thylakoid membrane were detected as a result of 3-hours heat treatment at 40°C. In the senescent primary leaf of 11-day-old seedlings, a thermoinduced decrease in the electrical component of the proton motive force and an increase in the transthylakoid proton gradient were detected. It was concluded that the electrochemical potential of thylakoid membranes reacts differently to heat effects in Hordeum vulgare L. seedlings of different ages.