Harnessing photosynthetic COO discrimination dynamics under leaf water nonsteady state to estimate mesophyll conductance: a new, regression-based method.

Mesophyll conductance (g) is a crucial plant trait that can significantly limit photosynthesis. Measurement of photosynthetic COO discrimination (ΔO) has proved to be the only viable means of resolving g in both C and C plants. However, the currently available methods to exploit ΔO for g estimation are error prone due to their inadequacy in constraining the degree of oxygen isotope exchange (θ) during mesophyll CO hydration.

Mesophyll conductance exerts a significant limitation on photosynthesis during light induction.

Past studies have established mesophyll diffusion conductance to CO (g ) as a variable and significant limitation to plant photosynthesis under steady-state conditions. However, the role of g in influencing photosynthesis (A) during the transient period of light induction is largely unknown. We combined gas exchange measurements with laser-enabled carbon isotope discrimination measurements to assess g during photosynthetic induction, using Arabidopsis as the measurement species.

Bicarbonate stimulates non-structural carbohydrate pools of Camptotheca acuminata.

The role of root-derived dissolved inorganic carbon (DIC) has been emphasized lately, as it can provide an alternative source of carbon for photosynthesis. The fate of newly fixed DIC and its effect on non-structural carbohydrate (NSC) pools has not been thoroughly elucidated to date. To this end, we used C (NaHCO ) as a substrate tracer to investigate the incorporation of newly fixed bicarbonate into the plant organs and NSC compounds of Camptotheca acuminata seedlings for 24 and 72 h.

Root-derived bicarbonate assimilation in response to variable water deficit in Camptotheca acuminate seedlings.

Water deficit is one of the key factors that limits the carbon (C) assimilation and productivity of plants. The effect of variable water deficit on recently root-derived bicarbonate assimilation in Camptotheca acuminate seedlings was investigated. Three-month-old seedlings were subjected to three water regimes, well-watered (WW), moderate stress (MS), and severe stress (SS) induced by polyethyleneglycol, in conjunction with relatively high (H) and low (L) natural C-abundance of NaHCO-labeled treatments in hydroponics for 14 days.