PHYSIOLOGICAL–ENVIRONMENTAL INTERACTIONS IN LICHENS

• Published in: New Phytologist
• Main Authors: KERSHAW, K. A., MACFARLANE, J. D., TYSIACZNY, M. J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1977
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.1111/j.1469-8137.1977.tb02221.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1469-8137.1977.tb02221.x; https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.1977.tb02221.x

SUMMARY The rapid decline of nitrogenase activity in Peltigera polydactyla and P. canina var. praetextata in the dark, to approximately 50% of its normal level in the light, is shown to be very temperature dependent and is not evident at temperatures of 15°C or less. An exogenous supply of 6% glucose, however, fails to eliminate the decline of activity. Nitrogenase activity in the dark is also completely dependent on aerobic conditions with zero rates being recorded after 1 min in the dark under a helium/acetylene atmosphere. Evidence is presented which shows the actual level of decline of nitrogenase activity in the dark has a seasonal component. The results are discussed in relation to oxidative phosphorylation and the availability of carbohydrates throughout the seasons. The ability of P. polydactyla and P. canina var. praetextata to maintain high levels of nitrogenase activity in the dark at temperatures of 15°C or less suggests that a large proportion of the nitrogen fixed by lichens with a blue‐green phycobiont in temperate and low arctic regions, is at night.