9407979 McIntosh Plants, unlike other organisms, possess two respiratory pathways: the "normal" cytochrome pathway and an "alternative pathway". This is important because alternative pathway respiration does not contribute to a proton gradient across the inner mitochondrial membrane and thus electrons that flow down this pathway do not conserve energy. All plants apparently contain an alternative pathway of respiration, that may be induced in response to developmental signals (such as increased carbohydrate status and flowering) and many environmental stimuli (such as cold, wounding, and endogenous salicylic acid concentrations). Why should plants have a more complex respiratory system than most other eukaryotes and what is its funciton? Although it is not possible to form a complete answer now, alternative pathway respiration is most probably involved in the regulation of energy/carbon balance in plants in response to varying demands of development and the environment. A classic approach to dissect the importance and function of any pathway is to study mutants in the pathway. No plant mutants have been isolated for alternative pathway respiration, possibly because of its proposed regulatory functions. The approach put forward in this research is to create plant lines with altered amounts of cytochrome oxidase and alternative oxidase, and to use these lines to elucidate the genetic, biochemical, and biophysical regulation of respiratory energy balance in plants. Tomato and potato plants will be used as experimental systems. ***
