New perspectives in the biophysics and physiology of bryophytes

This chapter describes advances in the biophysics of membrane transport, and the biochemistry of CO₂ fixation, in bryophytes. The fundamentals of transport of the plasmalemma and the tonoplast of bryophytes closely resemble those of their nearest relatives, i.e. charophycean algae and vascular plants. The chapter considers work on photosynthetic inorganic carbon assimilation by bryophytes, emphasizing the transport processes involved as well as the biochemistry of CO₂ fixation and the ecophysiological implications of the findings. In aquatic mosses in rapidly flowing water, and in some terrestrial bryophytes, there is little restriction of CO₂ fixation by CO₂ diffusion. However, there are several unexplained findings and both those bryophytes with C₃ physiology and the minority with a CO₂-concentrating mechanism need further investigation. Use of stable isotope measurements as an additional approach to studying CO2 supply constraints in that majority of bryophytes which have C₃ physiology shows agreement with other estimates of CO₂ conductances in some cases.