Design and Use of a Digitally Controlled Device for Accurate, Multiplexed Gas Exchange Measurements of the Complete Foliar Parts of Plants

George, Gavin M.; Kölling, Katharina; Kuenzli, Roland; Hirsch‐Hoffmann, Matthias; Flütsch, Patrick; Zeeman, Samuel C.

doi:10.1007/978-1-4939-7786-4_3

Cited by 8 publications

(7 citation statements)

References 13 publications

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“…To investigate photosynthetic CO 2 assimilation and respiration in FBA-deficient plants in more detail, the single mutants were monitored via infrared gas analysis in custom-made chambers ( Fig. 5A ; Kölling et al, 2015a ; George et al. 2018 ) using the same conditions as for plant cultivation (illumination at 150 μmol m −2 s −1 , 20 °C, 70% relative humidity, 380 ppm CO 2 ).…”

Section: Resultsmentioning

confidence: 99%

“…Gas exchange experiments were carried out using three to four mutant and three to four wild-type plants in parallel, as described by Kölling et al (2015a) . Data were processed using custom-built software described by George et al (2018) . Plants were introduced into measurement chambers a day before measurement to allow acclimation, then measured continuously for a full day and night.…”

Section: Methodsmentioning

confidence: 99%

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Distinct plastid fructose bisphosphate aldolases function in photosynthetic and non-photosynthetic metabolism in Arabidopsis

Carrera

George

Fischer-Stettler

et al. 2021

Journal of Experimental Botany

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Plastid metabolism is critical in both photoautotrophic and heterotrophic plant cells. In chloroplasts, fructose-1,6-bisphosphate aldolase (FBA) catalyses the formation of both fructose 1,6-bisphosphate and sedoheptulose 1,7-bisphosphate within the Calvin-Benson cycle. Three Arabidopsis genes, AtFBA1-AtFBA3, encode plastidial isoforms of FBA, but the contributions of each isoform is unknown. Phylogenetic analysis indicates that FBA1 and FBA2 derive from a recently duplicated gene, while FBA3 is a more ancient paralog. The fba1 mutants are phenotypically indistinguishable from the wild type, while both fba2 and fba3 have reduced growth. We show that FBA2 is the major isoform in leaves, contributing most of the measurable activity. Partial redundancy with FBA1 allows both single mutants to survive, but combining both mutations is lethal, indicating a block of photoautotrophy. In contrast, FBA3 is expressed predominantly in heterotrophic tissues, especially the leaf and root vasculature, but not in the leaf mesophyll. We show that the loss of FBA3 affects plastidial glycolytic metabolism of the root, potentially limiting the biosynthesis of essential compounds such as amino acids. However, grafting experiments suggest that fba3 is dysfunctional in leaf phloem transport, and we suggest that a block in photoassimilate export from leaves causes the buildup of high carbohydrate levels and retarded growth.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Distinct plastid fructose bisphosphate aldolases function in photosynthetic and non-photosynthetic metabolism in Arabidopsis

Carrera

George

Fischer-Stettler

et al. 2021

Journal of Experimental Botany

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“…Plants were subjected to a two-pulsed-light treatment, during which plants were given pulses of light and darkness of 2 h each. This began at the EoN, after 30 min of dark adaptation under 150 mmol m 22 s 21 white light illumination, which is common for Arabidopsis (George et al, 2018). Given the purpose of our gas exchange measurements to compare stomatal opening kinetics between genotypes, g s and A were normalized to the values at the EoN to facilitate the comparison of the velocity in the increase of the two parameters.…”

Section: Bl-induced Guard Cell Starch Degradation Yields Glcmentioning

confidence: 99%

Guard Cell Starch Degradation Yields Glucose for Rapid Stomatal Opening in Arabidopsis

et al. 2020

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Starch in Arabidopsis (Arabidopsis thaliana) guard cells is rapidly degraded at the start of the day by the glucan hydrolases a-AMYLASE3 (AMY3) and b-AMYLASE1 (BAM1) to promote stomatal opening. This process is activated via phototropinmediated blue light signaling downstream of the plasma membrane H 1-ATPase. It remains unknown how guard cell starch degradation integrates with light-regulated membrane transport processes in the fine control of stomatal opening kinetics. We report that H 1 , K 1 , and Cl 2 transport across the guard cell plasma membrane is unaltered in the amy3 bam1 mutant, suggesting that starch degradation products do not directly affect the capacity to transport ions. Enzymatic quantification revealed that after 30 min of blue light illumination, amy3 bam1 guard cells had similar malate levels as the wild type, but had dramatically altered sugar homeostasis, with almost undetectable amounts of Glc. Thus, Glc, not malate, is the major starchderived metabolite in Arabidopsis guard cells. We further show that impaired starch degradation in the amy3 bam1 mutant resulted in an increase in the time constant for opening of 40 min. We conclude that rapid starch degradation at dawn is required to maintain the cytoplasmic sugar pool, clearly needed for fast stomatal opening. The conversion and exchange of metabolites between subcellular compartments therefore coordinates the energetic and metabolic status of the cell with membrane ion transport.

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“…At the start of the day of the experiment, plants were transferred to light of 105-μmol quanta m −2 s −1 . For experiments in which [CO 2 ] was decreased, individual plants were placed in a multi-chamber, computer-controlled, infrared gas analyzer-coupled system for the continuous measurement of gas exchange in whole-plant shoots or rosettes (ETH Gas Exchange System-2; Kölling et al, 2015 ; George et al, 2018 ), and rates of photosynthesis were continuously monitored. Control plants were placed beside the chambers, in the same environmental conditions.…”

Section: Methodsmentioning

confidence: 99%

Rising rates of starch degradation during daytime and trehalose 6-phosphate optimize carbon availability

et al. 2022

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Many plants, including Arabidopsis (Arabidopsis thaliana), accumulate starch in the light and remobilize it to support maintenance and growth at night. Starch synthesis and degradation are usually viewed as temporally separate processes. Recently, we reported that starch is also degraded in the light. Degradation rates are generally low early in the day but rise with time. Here, we show that the rate of degradation in the light depends on time relative to dawn rather than dusk. We also show that degradation in the light is inhibited by trehalose 6-phosphate, a signal for sucrose availability. The observed responses of degradation in the light can be simulated by a skeletal model in which the rate of degradation is a function of starch content divided by time remaining until dawn. The fit is improved by extension to include feedback inhibition of starch degradation by trehalose 6-phosphate. We also investigate possible functions of simultaneous starch synthesis and degradation in the light, using empirically parameterized models and experimental approaches. The idea that this cycle buffers growth against falling rates of photosynthesis at twilight is supported by data showing that rates of protein and cell wall synthesis remain high during a simulated dusk twilight. Degradation of starch in the light may also counter over-accumulation of starch in long photoperiods and stabilize signaling around dusk. We conclude that starch degradation in the light is regulated by mechanisms similar to those that operate at night and is important for stabilizing C availability and signaling, thus optimizing growth in natural light conditions.

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Design and Use of a Digitally Controlled Device for Accurate, Multiplexed Gas Exchange Measurements of the Complete Foliar Parts of Plants

Cited by 8 publications

References 13 publications

Distinct plastid fructose bisphosphate aldolases function in photosynthetic and non-photosynthetic metabolism in Arabidopsis

Distinct plastid fructose bisphosphate aldolases function in photosynthetic and non-photosynthetic metabolism in Arabidopsis

Guard Cell Starch Degradation Yields Glucose for Rapid Stomatal Opening in Arabidopsis

Rising rates of starch degradation during daytime and trehalose 6-phosphate optimize carbon availability

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