Although the light regimes used by Yin and Johnson (2000) are quite different from our sunfleck treatments, it is plausible that the reduction in 1-qp (Fig. 2c) and the increase in ETR (Fig. 3c) found

in LSF 650 reflects, at least in part, the acclimatory enhancement of PSII activity described in that study. Notably, a single 12-h exposure to C 85 or C 120, or a daily 40-min exposure to LSF 650 for a couple of days was enough to bring about small but significant www.selleckchem.com/products/Erlotinib-Hydrochloride.html initial changes in 1-qp and ETR (Figs. 2c and 3c), demonstrating the ability of Arabidopsis plants to rapidly increase the capacity for photosynthetic electron transport. Unlike in C 85 and C 120, however, the increased electron transport in LSF 650 did not lead to higher starch accumulation or enhanced leaf expansion (Fig. 11, lower boxes). The 40-min exposure selleck chemicals llc to LSF, which raised the leaf temperature from 21~22 to 27~28 °C, may have promoted photorespiration (if the treatment decreased the stomatal conductance)

and/or mitochondrial respiration, including rapid upregulation of alternative oxidase (Osmond and Grace 1995; Leakey et al. 2004; Yoshida et al. 2011). Also, additional carbon fixed during LSF may have been transported out of the mature leaves to support sink organs such as growing roots, as was found in Nicotiana tabacum upon PAR increase from 60 to 300 μmol photons m−2 s−1 (Nagel et al. 2006). Together, Atezolizumab research buy these results, showing distinct acclimatory responses of Col-0 plants to constant light, LSF, and SSF, strongly suggest the involvement of light intensity, duration, and frequency in adjusting photoprotection and carbon gain at different levels (Fig. 11). Plant acclimation entails activation/deactivation and upregulation/downregulation of various physiological processes, including restructuring and reorganization

of relevant components. In addition to the intensity and acuteness of the signal, factors such as how quickly each of these processes can react (response time) and how long certain signals can last in the cell probably gain importance for determining the acclimatory response to fluctuating conditions. Building on the knowledge provided by the numerous studies on acclimation to (constant or less dynamic) HL and LL, future investigations could elucidate the roles of different processes and signals associated with regulation of photosynthetic acclimation, e.g., plastoquinone and stromal redox state, ATP/ADP ratio, sugars, and ROS (Pfannschmidt 2003; Walters 2005), in fluctuating light environment.