Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Nutrient and genotypic effects on CO2-responsiveness: photosynthetic regulation in Leucadendron species of a nutrient-poor environment

Nutrient and genotypic effects on CO2-responsiveness: photosynthetic regulation in Leucadendron... Abstract Four South African Leucadendron congenerics with divergent soil N and P preferences were grown as juveniles at contrasting nutrient concentrations at ambient (350 µmol mol−1) and elevated (700 µmol mol−1) atmospheric CO2 levels. Photosynthetic parameters were related to leaf nutrient and carbohydrate status to reveal controls of carbon uptake rate. In all species, elevated CO2 depressed both the maximum Rubisco catalytic activity (Vc,max, by 19–44%) and maximum electron transport rate (Jmax, by 13–39%), indicating significant photosynthetic acclimation of both measures. Even so, all species had increased maximum light-saturated rate of net CO2 uptake (Amax) at the elevated growth CO2 level, due to higher intercellular CO2 concentration (ci). Leaf nitrogen concentration was central to photosynthetic performance, correlating with Amax, Vc,max and Jmax. Vc,max and Jmax were linearly co-correlated, revealing a relatively invariable Jmax:Vc,max ratio, probably due to N resource optimization between light harvesting (RuBP regeneration) and carboxylation. Leaf total non-structural carbohydrate concentration (primarily starch) increased in high CO2, and was correlated with the reduction in Vc,max and Jmax. Apparent feedback control of Vc,max and Jmax was thus surprisingly consistent across all species, and may regulate carbon exchange in response to end-product fluctuation. If so, elevated CO2 may have emulated an excess end-product condition, triggering both Vc,max and Jmax down-regulation. In Leucadendron, a general physiological mechanism seems to control excess carbohydrate formation, and photosynthetic responsiveness to elevated CO2, independently of genotype and nutrient concentration. This mechanism may underlie photosynthetic acclimation to source:sink imbalances resulting from such diverse conditions as elevated CO2, low sink strength, low carbohydrate export, and nutrient limitation. Carbohydrate, elevated CO2, nitrogen, photosynthesis, Proteaceae This content is only available as a PDF. © Oxford University Press 1999 © Oxford University Press 1999 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Experimental Botany Oxford University Press

Nutrient and genotypic effects on CO2-responsiveness: photosynthetic regulation in Leucadendron species of a nutrient-poor environment

Loading next page...
 
/lp/oxford-university-press/nutrient-and-genotypic-effects-on-co-2-responsiveness-photosynthetic-4NGQMKyz18

References (27)

Publisher
Oxford University Press
Copyright
Copyright © 2022 Society for Experimental Biology
ISSN
0022-0957
eISSN
1460-2431
DOI
10.1093/jxb/50.333.533
Publisher site
See Article on Publisher Site

Abstract

Abstract Four South African Leucadendron congenerics with divergent soil N and P preferences were grown as juveniles at contrasting nutrient concentrations at ambient (350 µmol mol−1) and elevated (700 µmol mol−1) atmospheric CO2 levels. Photosynthetic parameters were related to leaf nutrient and carbohydrate status to reveal controls of carbon uptake rate. In all species, elevated CO2 depressed both the maximum Rubisco catalytic activity (Vc,max, by 19–44%) and maximum electron transport rate (Jmax, by 13–39%), indicating significant photosynthetic acclimation of both measures. Even so, all species had increased maximum light-saturated rate of net CO2 uptake (Amax) at the elevated growth CO2 level, due to higher intercellular CO2 concentration (ci). Leaf nitrogen concentration was central to photosynthetic performance, correlating with Amax, Vc,max and Jmax. Vc,max and Jmax were linearly co-correlated, revealing a relatively invariable Jmax:Vc,max ratio, probably due to N resource optimization between light harvesting (RuBP regeneration) and carboxylation. Leaf total non-structural carbohydrate concentration (primarily starch) increased in high CO2, and was correlated with the reduction in Vc,max and Jmax. Apparent feedback control of Vc,max and Jmax was thus surprisingly consistent across all species, and may regulate carbon exchange in response to end-product fluctuation. If so, elevated CO2 may have emulated an excess end-product condition, triggering both Vc,max and Jmax down-regulation. In Leucadendron, a general physiological mechanism seems to control excess carbohydrate formation, and photosynthetic responsiveness to elevated CO2, independently of genotype and nutrient concentration. This mechanism may underlie photosynthetic acclimation to source:sink imbalances resulting from such diverse conditions as elevated CO2, low sink strength, low carbohydrate export, and nutrient limitation. Carbohydrate, elevated CO2, nitrogen, photosynthesis, Proteaceae This content is only available as a PDF. © Oxford University Press 1999 © Oxford University Press 1999

Journal

Journal of Experimental BotanyOxford University Press

Published: Apr 1, 1999

There are no references for this article.