Plant respiration is an important component of the global carbon budget, and its response to temperature is dynamic on long and short timescales. Here, we examine the thermal acclimation of respiration in Chionochloa pallens and C. rubra, two species of native tussock grass growing on Mt. Hutt, New Zealand, to short term (several day) temperature fluctuations in the field and under laboratory conditions. In particular, using a novel gas sampling technique, we investigate whether in vivo engagement of alternative oxidase (AOX), which catalyzes the so-called “energy wasteful” CN-resistant respiratory pathway in plants, plays a role in regulating acclimation on short timescales.
We find evidence of acclimation of respiration in snow tussock to as little as 24-hour changes in temperature; R10 and Q10 increase with cold treatment and decrease again with a reversal to warm conditions. Respiratory parameters are correlated with changes in AOX engagement, protein expression of AOX and cytochrome c oxidase, carbohydrates, and chlorophyll fluorescence yield. Understanding how respiratory acclimation in plants is regulated will help scale predictions of carbon cycling from the plant to the global level.