Antisense Reduction of NADP-Malic Enzyme in <i>Flaveria bidentis</i> Reduces Flow of CO2 through the C4 Cycle

Pengelly, Jasper J. L.; Tan, Jackie; Furbank, Robert T.; Caemmerer, Susanne von

doi:10.1104/pp.112.203240

Cited by 36 publications

(45 citation statements)

References 38 publications

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“…4). NADP-ME influenced both the convexity and maximal CO 2 uptake rate of the A-C i curve, which is consistent with previous experimental observations (Pengelly et al, 2012).…”

Section: Control Properties Of Key Enzymes For C4 Photosynthetic Effisupporting

confidence: 81%

Elements Required for an Efficient NADP-Malic Enzyme Type C4 Photosynthesis

2014

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C4 photosynthesis has higher light, nitrogen, and water use efficiencies than C3 photosynthesis. Although the basic anatomical, cellular, and biochemical features of C4 photosynthesis are well understood, the quantitative significance of each element of C4 photosynthesis to the high photosynthetic efficiency are not well defined. Here, we addressed this question by developing and using a systems model of C4 photosynthesis, which includes not only the Calvin-Benson cycle, starch synthesis, sucrose synthesis, C4 shuttle, and CO 2 leakage, but also photorespiration and metabolite transport between the bundle sheath cells and mesophyll cells. The model effectively simulated the CO 2 uptake rates, and the changes of metabolite concentrations under varied CO 2 and light levels. Analyses show that triose phosphate transport and CO 2 leakage can help maintain a high photosynthetic rate by balancing ATP and NADPH amounts in bundle sheath cells and mesophyll cells. Finally, we used the model to define the optimal enzyme properties and a blueprint for C4 engineering. As such, this model provides a theoretical framework for guiding C4 engineering and studying C4 photosynthesis in general.

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“…4). NADP-ME influenced both the convexity and maximal CO 2 uptake rate of the A-C i curve, which is consistent with previous experimental observations (Pengelly et al, 2012).…”

Section: Control Properties Of Key Enzymes For C4 Photosynthetic Effisupporting

confidence: 81%

Elements Required for an Efficient NADP-Malic Enzyme Type C4 Photosynthesis

2014

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“…1), suggesting that f can be maintained regardless of changes in A net . It has been demonstrated that A net is typically determined by total available energy, whereas f is determined by x (Siebke et al, 1997;von Caemmerer, 2000;Ubierna et al, 2011;Pengelly et al, 2012). Over time, the coordination of both cycles was achieved under all light qualities; however, the rate at which this balance was achieved differed between maize and M. giganteus.…”

Section: Discussion Light Quality and A Netmentioning

confidence: 99%

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

et al. 2014

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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.

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“…2c). It is difficult to disrupt this coordination through environmental perturbations, however molecular manipulations of F. bidentis by RNAi technologies have shown that reductions of Rubisco content disturbs the balance and leads to increased leakiness whereas reductions in C 4 cycle capacity through reduction in NADP malic enzyme reduces leakiness demonstrating that the balancing of biochemical capacities is important (von Caemmerer et al, 1997;Pengelly et al, 2012). However, it is puzzling that a different balance in the capacity of the carboxylases, i.e.…”

Section: Photosynthesis In Species With Kranz Anatomymentioning

confidence: 95%

Single cell C4 photosynthesis in aquatic and terrestrial plants: A gas exchange perspective

2014

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a b s t r a c tAnother "green revolution" is needed for crop yields to meet the demands for food and this has provided a new focus on photosynthesis research. Many important crops have the C 3 photosynthetic pathway and a range of options for enhancing leaf photosynthesis in C 3 species are being tested. George Bowes' pioneering research elucidated the inducible single cell C 4 photosynthetic mechanism of aquatic plants such as Hydrilla verticillata. Here we review the efficacy of single cell C 4 photosynthesis by comparing the physiology of terrestrial Kranz C 4 photosynthesis with that of terrestrial and aquatic single cell C 4 photosynthesis. The comparison shows that the terrestrial single cell system which involves spatially separated cytoplasmic domains and dimorphic chloroplasts equals Kranz C 4 photosynthesis in efficiency; whereas, the simpler aquatic single cell system employed by H. verticillata which operates the C 4 pathway between cytoplasmic space and chloroplasts is less efficient due to diffusive constraints. Nevertheless, understanding this readily inducible C 4 pathway may provide valuable lessons for improving C 3 photosynthesis by enhancing chloroplast CO 2 concentrations.

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Antisense Reduction of NADP-Malic Enzyme in Flaveria bidentis Reduces Flow of CO2 through the C4 Cycle

Cited by 36 publications

References 38 publications

Elements Required for an Efficient NADP-Malic Enzyme Type C4 Photosynthesis

Elements Required for an Efficient NADP-Malic Enzyme Type C4 Photosynthesis

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

Single cell C4 photosynthesis in aquatic and terrestrial plants: A gas exchange perspective

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