Abstract
Chlororespiration is a process in the chloroplast which can be interpreted to be similar to respiration in prokaryotic photosynthetic organisms, in which photosynthetic and respiratory electron flow occur in the same membranes. In chlororespiration, electron flow is assumed to be mediated by a plastid NAD(P)H dehydrogenase (NDH) complex and a plastid terminal oxidase (PTOX). These two components facilitate electron flow from stromal reductants, mainly NADPH, to final electron acceptor oxygen, via plastoquinone PQ in the thylakoids. In this study, we analyzed a physiological role of chlororespiration in vivo. We established a method to detect the activity of chlororespiration in vivo, on the basis of analysis of chlorophyll fluorescence yield in mutants either lacking NDH complex or a putative type II NAD(P)H dehydrogenase (NDC1), which has recently been reported to locate in chloroplasts as well as in mitochondria. It was suggested that the activity of chlororespiration is enhanced in response to growth light intensity.
