Stomatal conductance, not biochemistry, drives low temperature acclimation of photosynthesis in Populus balsamifera, regardless of nitrogen availability

Abstract

Low-temperature thermal acclimation may require adjustments to N and water use to sustain photosynthesis because of slow enzyme functioning and high water viscosity. However, understanding of photosynthetic acclimation to temperatures below 11 °C is limited.• We acclimated Populus balsamifera to 6 °C and 10 °C (6A and 10A, respectively) and provided the trees with either high or low N fertilizer. We measured net CO 2 assimilation (A net ), stomatal conductance (g s ), maximum rates of Rubisco carboxylation (V cmax ), electron transport (J max ) and dark respiration (R d ) at leaf temperatures of 2, 6, 10, 14 and 18 °C, along with leaf N concentrations.• The 10A trees had higher A net than the 6A trees at warmer leaf temperatures, which was correlated with higher g s in the 10A trees. The instantaneous temperature responses of V cmax , J max and R d were similar for trees from both acclimation temperatures. While soil N availability increased leaf N concentrations, this had no effect on acclimation of photosynthesis or respiration.• Our results indicate that acclimation below 11 °C occurred primarily through changes in stomatal conductance, not photosynthetic biochemistry, and was unaffected by short-term N supply. Thermal acclimation of stomatal conductance should therefore be a priority for future carbon cycle model development.

A Bibliometric Analysis Unveils Valuable Insights into the Past, Present, and Future Dynamics of Plant Acclimation to Temperature

“…Photosynthesis has been considered the most direct indicator to evaluate plant temperature acclimation during this period. Reference [68] studied the cold acclimation of Populus balsamifera photosynthesis. Reference [69] proposed a modeling method for thermal acclimation to photosynthesis and respiration in plants.…”

Genome-Wide Analysis of the Expansin Gene Family in Populus and Characterization of Expression Changes in Response to Phytohormone (Abscisic Acid) and Abiotic (Low-Temperature) Stresses

“…A 100 µM [64,69] ABA solution was poured onto the crushed tissue culture medium so that the plant roots were immersed in the solution. For the low-temperature treatment, the plants were placed in a Percival incubator (Percival, CU-22L) with the temperature set to 10 • C [70,71]. The leaves of the plants were harvested at 6 time points (0, 3, 6, 12, 24 and 48 h) [64,69,72] and immediately frozen at −80 • C.…”

CO<sub>2</sub> Demand-Supply Coordination in Photosynthesis Reflecting the Plant-Environment Interaction: Extension and Parameterization of Demand Function and Supply Function

“…Photosynthesis can be roughly divided into two components, the biochemical process, and the CO 2 diffusion process [2] [10] [11]. The biochemical process includes Rubisco carboxylation, the regeneration of CO 2 receptor RuBP, and utilization and transport of photosynthates [12].…”