Ontogenetic aspects of plant respiration (by the example of Rubus chamaemorus L.)

Respiration, content of soluble carbohydrates and phenolics, level of lipid peroxidation, and activity of peroxidase and polyphenoloxidase were investigated in the leaves of cloudberry (Rubus chamaemorus L.) in different stages of shoot development. Age dependence of respiration was wave like with peaks associated with the periods of vegetative growth and fruit bearing. Prior to the onset of fruit bearing, respiration was clearly suppressed, while the content of soluble carbohydrates rose. In the course of development, contribution of cytochrome pathway to total respiration changed more drastically than participation of energy-wise ineffective alternative pathway. Activation of residual (nonmitochondrial) respiration observed in the postgenerative period directly correlated with a rise in activity of polyphenoloxidase and peroxidase in the leaves. The results show that ontogenetic changes in leaf respiration are complex and depend on genetically predetermined processes of plant growth and development. Behavior of respiration and its components predictably reflects changes in the direction and intensity of overall metabolism of plants associated with strict order of alternation of regular age states.