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Acclimation to low light by C4 maize: implications for bundle sheath leakiness
Author(s) -
BELLASIO CHANDRA,
GRIFFITHS HOWARD
Publication year - 2014
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12194
Subject(s) - acclimatization , rubisco , chemistry , limiting , respiration , photosynthesis , botany , biophysics , biology , biochemistry , mechanical engineering , engineering
Abstract C4 plants have a biochemical carbon concentrating mechanism ( CCM ) that increases CO 2 concentration around ribulose bisphosphate carboxylase oxygenase ( R ubisco) in the bundle sheath ( BS ). Under limiting light, the activity of the CCM generally decreases, causing an increase in leakiness, ( Φ ), the ratio of CO 2 retrodiffusing from the BS relative to C4 carboxylation processes. Maize plants were grown under high and low light regimes (respectively HL , 600 versus LL , 100 μ E m −2 s −1 ). Short‐term acclimation of Φ was compared from isotopic discrimination (Δ), gas exchange and photochemistry. Direct measurement of respiration in the light, and ATP production rate ( J ATP ), allowed us use a novel approach to derive Φ , compared with the conventional fitting of measured and predicted Δ. HL grown plants responded to decreasing light intensities with the well‐documented increase in Φ . Conversely, LL plants showed a constant Φ , which has not been observed previously. We explain the pattern by two contrasting acclimation strategies: HL plants maintained a high CCM activity at LL , resulting in high CO 2 overcycling and increased Φ ; LL plants acclimated by down‐regulating the CCM , effectively optimizing scarce ATP supply. This surprising plasticity may limit the impact of Φ ‐dependent carbon losses in leaves becoming shaded within developing canopies.