The Coordination of C4 Photosynthesis and the CO2-Concentrating Mechanism in Maize and Miscanthus × giganteus in Response to Transient Changes in Light Quality    

Abstract

Unequal absorption of photons between photosystems I and II, and between bundle-sheath and mesophyll cells, are likely to affect the efficiency of the CO 2 -concentrating mechanism in C 4 plants. Under steady-state conditions, it is expected that the biochemical distribution of energy (ATP and NADPH) and photosynthetic metabolite concentrations will adjust to maintain the efficiency of C 4 photosynthesis through the coordination of the C 3 (Calvin-Benson-Bassham) and C 4 (CO 2 pump) cycles. However, under transient conditions, changes in light quality will likely alter the coordination of the C 3 and C 4 cycles, influencing rates of CO 2 assimilation and decreasing the efficiency of the CO 2 -concentrating mechanism. To test these hypotheses, we measured leaf gas exchange, leaf discrimination, chlorophyll fluorescence, electrochromatic shift, photosynthetic metabolite pools, and chloroplast movement in maize (Zea mays) and Miscanthus 3 giganteus following transitional changes in light quality. In both species, the rate of net CO 2 assimilation responded quickly to changes in light treatments, with lower rates of net CO 2 assimilation under blue light compared with red, green, and blue light, red light, and green light. Under steady state, the efficiency of CO 2 -concentrating mechanisms was similar; however, transient changes affected the coordination of C 3 and C 4 cycles in M. giganteus but to a lesser extent in maize. The species differences in the ability to coordinate the activities of C 3 and C 4 cycles appear to be related to differences in the response of cyclic electron flux around photosystem I and potentially chloroplast rearrangement in response to changes in light quality.

Carbon isotopes and water use efficiency in C4 plants

“…In fact, using the full formulation of the Δ 13 Cleaf model developed byFarquhar (1984) typically indicates little to no change in φ under low light[17,36,37,41]. Additionally, φ was generally found to acclimate to rapid changes in light quality[42]. Therefore, direct measurements of Δ 13 Cleaf generally indicate that C4 plants have a remarkable ability to coordinate the metabolic flux through the C4 and C3 cycles, and that φ is relatively constant between species and across different growth conditions.…”

Plants responses to drought and shade environments

“…These environmental factors affect plants' growth, morphology, physiology and biochemistry. Many research works have shown that light plays key role in changing the traits of plants (Lee et al, 2013;Ranade and García-Gil, 2013;Adam and Cavaleri, 2014;Kuehne et al, 2014;Lavinsky et al, 2014;Sun et al, 2014). Plants' morphological and physiological differences in growth reactions to shade or low light intensity are exceedingly important in all types of forests in the world.…”

The Coordination of Gene Expression within Photosynthesis Pathway for Acclimation of C4 Energy Crop Miscanthus lutarioriparius

“…The amount of PPDK, rbcL, ATPase beta subunit was up-regulated in the leaf proteome as heat-response proteins of M. sinensis (Sharmin et al, 2013 ). In contrast with the acclimation experiments to single controlled environment factor (Sun et al, 2012 , 2014 ; Sharmin et al, 2013 ), 80.8% of M. lutarioriparius photosynthetic transcripts were coordinated at transcription level across two contrasting field environments.…”

“…In studying the acclimation of M. × giganteus to transient changes in light quality, transient changes in light treatments quickly lower the rate of net CO 2 assimilation and disrupt the coordination of C 3 and C 4 cycles, which potentially seems to affect cyclic electron flux around photosystem I and chloroplast rearrangement (Sun et al, 2012 , 2014 ). Meanwhile, M. × giganteus acclimates poorly to low water availability (Clifton-Brown and Lewandowski, 2000 ) and photosynthetic performance is reduced by a decrease in stomatal conductance, which is followed with a decrease in chlorophyll content and chlorophyll fluorescence (Ings et al, 2013 ).…”