Rethinking the potential productivity of crassulacean acid metabolism by integrating metabolic dynamics with shoot architecture, using the example of <i>Agave tequilana</i>

Smith, J. Andrew C.; Zhu, Xin‐Guang; Long, Stephen P.

doi:10.1111/nph.19128

Cited by 3 publications

(1 citation statement)

References 110 publications

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“…Most comparative physiology approaches would not be sufficient to determine if low % IAS aids the CAM cycle by reducing g m , or if it is a spandrel that occurs from maximizing the volume of cells. However, several models have been made that describe the physiology of CAM plants ( Owen and Griffiths, 2013 ; Bartlett et al ., 2014 ; Hartzell et al ., 2018 , 2020 ; Töpfer et al ., 2020 ; Wang et al ., 2023 ). Models can be used to artificially alter physiological and anatomical parameters, in ways that may not occur in nature.…”

Section: The Architecture Of Photosynthetic Organsmentioning

confidence: 99%

Low internal air space in plants with crassulacean acid metabolism may be an anatomical spandrel

Leverett,

Borland,

Inge

et al. 2023

Annals of Botany

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Crassulacean Acid Metabolism (CAM) is a photosynthetic adaptation found in at least 38 plant families. Typically, the anatomy of CAM plants is characterised by large photosynthetic cells and a low percentage of leaf volume comprised of internal air space (% IAS). It has been suggested that reduced mesophyll conductance (gm) arising from low % IAS benefits CAM plants by preventing the movement of CO2 out of cells and ultimately minimising leakage of CO2 from leaves into the atmosphere during day-time decarboxylation. Here, we propose that low % IAS does not provide any adaptive benefit to CAM plants, because stomatal closure during phase III of CAM will result in internal concentrations of CO2 becoming saturated, meaning low gm will not have any meaningful impact on the flux of gasses within leaves. We suggest that low % IAS is more likely an indirect consequence of maximising the cellular volume within a leaf, to provide space for the overnight storage of malic acid during the CAM cycle.

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Section: The Architecture Of Photosynthetic Organsmentioning

confidence: 99%

Low internal air space in plants with crassulacean acid metabolism may be an anatomical spandrel

Leverett,

Borland,

Inge

et al. 2023

Annals of Botany

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Perspectives on improving photosynthesis to increase crop yield

Croce,

Carmo-Silva,

Cho

et al. 2024

The Plant Cell

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Improving photosynthesis, the fundamental process by which plants convert light energy into chemical energy, is a key area of research with great potential for enhancing sustainable agricultural productivity and addressing global food security challenges. This perspective delves into the latest advancements and approaches aimed at optimizing photosynthetic efficiency. Our discussion encompasses the entire process, beginning with light harvesting and its regulation and progressing through the bottleneck of electron transfer. We then delve into the carbon reactions of photosynthesis, focusing on strategies targeting the enzymes of the Calvin-Benson-Bassham (CBB) cycle. Additionally, we explore methods to increase CO2 concentration near the Rubisco, the enzyme responsible for the first step of CBB cycle, drawing inspiration from various photosynthetic organisms, and conclude this section by examining ways to enhance CO2 delivery into leaves. Moving beyond individual processes, we discuss two approaches to identifying key targets for photosynthesis improvement: systems modeling and the study of natural variation. Finally, we revisit some of the strategies mentioned above to provide a holistic view of the improvements, analyzing their impact on nitrogen use efficiency and on canopy photosynthesis.

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Metabolic modelling identifies mitochondrial Pi uptake and pyruvate efflux as key aspects of daytime metabolism and proton homeostasis in crassulacean acid metabolism leaves

Daems,

Shameer,

Ceusters

et al. 2024

New Phytologist

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Summary Crassulacean acid metabolism (CAM) leaves are characterized by nocturnal acidification and diurnal deacidification processes related with the timed actions of phosphoenolpyruvate carboxylase and Rubisco, respectively. How CAM leaves manage cytosolic proton homeostasis, particularly when facing massive diurnal proton effluxes from the vacuole, remains unclear. A 12‐phase flux balance analysis (FBA) model was constructed for a mature malic enzyme‐type CAM mesophyll cell in order to predict diel kinetics of intracellular proton fluxes. The charge‐ and proton‐balanced FBA model identified the mitochondrial phosphate carrier (PiC, Pi/H+ symport), which provides Pi to the matrix to sustain ATP biosynthesis, as a major consumer of cytosolic protons during daytime (> 50%). The delivery of Pi to the mitochondrion, co‐transported with protons, is required for oxidative phosphorylation and allows sufficient ATP to be synthesized to meet the high energy demand during CAM Phase III. Additionally, the model predicts that mitochondrial pyruvate originating from decarboxylation of malate is exclusively exported to the cytosol, probably via a pyruvate channel mechanism, to fuel gluconeogenesis. In this biochemical cycle, glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) acts as another important cytosolic proton consumer. Overall, our findings emphasize the importance of mitochondria in CAM and uncover a hitherto unappreciated role in metabolic proton homeostasis.

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Rethinking the potential productivity of crassulacean acid metabolism by integrating metabolic dynamics with shoot architecture, using the example of Agave tequilana

Cited by 3 publications

References 110 publications

Low internal air space in plants with crassulacean acid metabolism may be an anatomical spandrel

Low internal air space in plants with crassulacean acid metabolism may be an anatomical spandrel

Perspectives on improving photosynthesis to increase crop yield

Metabolic modelling identifies mitochondrial Pi uptake and pyruvate efflux as key aspects of daytime metabolism and proton homeostasis in crassulacean acid metabolism leaves

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