Abiotic Stress/Whole Plant Bio

Abstract

CS-19-3 - In planta Rubisco activation state and Rubisco activase activity using the rapid A/Ci response

Monday, July 16
3:58 PM - 4:18 PM

Rubisco activation state and Rubisco activase activity are crucial for the parameterization of photosynthesis, but are often not considered due to sampling difficulty or constraints. An in planta method would be ideal to better understand the responses of Rubisco activation state and Rubisco activase activity to environmental change and through time. Here we present a method for measuring Rubisco activation state in planta using the rapid photosynthetic CO2 response (RACiR) technique by taking the ratio of the initial slopes of RACiRs under maximally activating and deactivating conditions. We validated the RACiR ratios against paired in vitro Rubisco activation state data and subsequently measured time series of apparent Rubisco activation and deactivation in response to light in planta. Using RACiR ratios, we find that Rubisco deactivates rapidly at low light, and subsequent reactivation takes up to 30 min. Activation changes were less pronounced when comparing leaves switched between high and low CO2. We attribute these observations to the regulation of Rubisco activase activity in planta, as initial rates of Rubisco activation are comparable to, but generally less than, reported values of maximum Rubisco activase activity. The RACiR ratio technique opens the possibility to characterize Rubisco activation state and activase activity in planta, in situ, and in plants where extraction of functional Rubisco and activase is difficult or impossible.


 

Co-Authors

Amanda Cavanagh – University of Illinois; Patrick Hudson – The University of New Mexico; David Hanson – The University of New Mexico

Joseph R. Stinziano

Research Scientist
The University of New Mexico

Presentation(s):

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CS-19-3 - In planta Rubisco activation state and Rubisco activase activity using the rapid A/Ci response



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