Leaf Starch Turnover Occurs in Long Days and in Falling Light at the End of the Day

Fernández, Olivier; Ishihara, Hirofumi; George, Gavin M.; Mengin, Virginie; Flis, Anna; Sumner, Dean; Arrivault, Stéphanie; Feil, Regina; Lunn, John E.; Zeeman, Samuel C.; Smith, Alison M.; Stitt, Mark

doi:10.1104/pp.17.00601

Cited by 82 publications

(99 citation statements)

References 74 publications

(128 reference statements)

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“…The result for prr7 prr9 contrasts with previous studies, where starch accumulation in prr7 prr9 resembled that in wild-type Col-0 (Chew et al, 2017). After transfer to continuous light, starch accumulation slowed or plateaued in all genotypes ( Figure S3A; see also Fernandez et al, 2017).…”

Section: Diel Changes Of Starchcontrasting

confidence: 95%

“…We recently reported an explanation for the plateauing of starch accumulation upon transfer to continuous light (see Figure S3A). We found that starch degradation in the light is negligible early in the 24‐hr cycle but rises progressively from around ZT12 to ZT14 (Fernandez et al, ). This results in a cycle of starch synthesis and degradation, which progressively decreases the net rate of starch accumulation.…”

Section: Discussionmentioning

confidence: 83%

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Multiple circadian clock outputs regulate diel turnover of carbon and nitrogen reserves

Flis

Mengin

Ivakov

et al. 2019

Plant Cell & Environment

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Plants accumulate reserves in the daytime to support growth at night. Circadian regulation of diel reserve turnover was investigated by profiling starch, sugars, glucose 6-phosphate, organic acids and amino acids during a light-dark cycle and after transfer to continuous light in Arabidopsis wild-types and in mutants lacking dawn (lhy cca1), morning (prr7 prr9), dusk (toc1, gi) or evening (elf3) clock components. The metabolite time-series were integrated with published time-series for circadian clock transcripts to identify circadian outputs that regulate central metabolism. i) Starch accumulation was slower in elf3 and prr7 prr9. It is proposed that ELF3 positively regulates starch accumulation. ii) Reducing sugars were high early in the T-cycle in elf3, revealing that ELF3 negatively regulates sucrose recycling. iii) The pattern of starch mobilization was modified in all five mutants. A model is proposed in which dawn and dusk/evening components interact to pace degradation to anticipated dawn. iv) An endogenous oscillation of glucose 6-phosphate revealed that the clock buffers metabolism against the large influx of carbon from photosynthesis. v) Low levels of organic and amino acids in lhy cca1 and high levels in prr7 prr9 provide evidence that the dawn components positively regulate the accumulation of amino acid reserves.

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Section: Diel Changes Of Starchcontrasting

confidence: 95%

Section: Discussionmentioning

confidence: 83%

Multiple circadian clock outputs regulate diel turnover of carbon and nitrogen reserves

Flis

Mengin

Ivakov

et al. 2019

Plant Cell & Environment

Self Cite

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“…This was also reported to be the case in an earlier study conducted on silver birch in boreal conditions (Piispanen & Saranp€ a€ a 2001). Net sugar-to-starch turnover generally occurs during the day (Sala et al 2012), as sugar-to-starch turnover is favoured by increasing temperature (Kozlowski 1992;Charrier et al 2015;Zwieniecki et al 2015;Sperling et al 2017), light (Zeeman et al 2007) and sugar concentration (Escobar-Guti errez et al 1998), and is also affected by the circadian rhythm (Fernandez et al 2017). Increasing temperature will favour sugar-to-starch turnover, as starch synthesis is an energy-dependent process with a higher temperature dependency than the spontaneous starch-to-sugar degradation process (Zwieniecki et al 2015;Sperling et al 2017).…”

Section: Dynamics Of Nsc and Sap Pressurisation And Embolism Refillinsupporting

confidence: 70%

“…), and is also affected by the circadian rhythm (Fernandez et al . ). Increasing temperature will favour sugar‐to‐starch turnover, as starch synthesis is an energy‐dependent process with a higher temperature dependency than the spontaneous starch‐to‐sugar degradation process (Zwieniecki et al .…”

Section: Discussionmentioning

confidence: 97%

Water relations in silver birch during springtime: How is sap pressurised?

et al. 2018

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Positive sap pressures are produced in the xylem of birch trees in boreal conditions during the time between the thawing of the soil and bud break. During this period, xylem embolisms accumulated during wintertime are refilled with water. The mechanism for xylem sap pressurization and its environmental drivers are not well known. We measured xylem sap flow, xylem sap pressure, xylem sap osmotic concentration, xylem and whole stem diameter changes, and stem and root non-structural carbohydrate concentrations, along with meteorological conditions at two sites in Finland during and after the sap pressurisation period. The diurnal dynamics of xylem sap pressure and sap flow during the sap pressurisation period varied, but were more often opposite to the diurnal pattern after bud burst, i.e. sap pressure increased and sap flow rate mostly decreased when temperature increased. Net conversion of soluble sugars to starch in the stem and roots occurred during the sap pressurisation period. Xylem sap osmotic pressure was small in comparison to total sap pressure, and it did not follow changes in environmental conditions or tree water relations. Based on these findings, we suggest that xylem sap pressurisation and embolism refilling occur gradually over a few weeks through water transfer from parenchyma cells to xylem vessels during daytime, and then the parenchyma are refilled mostly during nighttime by water uptake from soil. Possible drivers for water transfer from parenchyma cells to vessels are discussed. Also the functioning of thermal dissipation probes in conditions of changing stem water content is discussed.

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“…Alison M. Smith (John Innes Centre, Norwich, UK) highlighted the importance of clock genes, which modulate starch production and degradation for efficient plant sustainment (Graf et al ., ; Scialdone et al ., ). Arabidopsis leaves modulate the rate of starch degradation according to the duration of the night, in order not to starve before dawn (Fernandez et al ., ). A better understanding of the dynamics of plant nutrient reserves may help engineering stress‐resistant or nutrient‐rich crops.…”

Section: Innovative Plant Technology: a Role For Basic And Applied Scmentioning

confidence: 97%

Facing global change: the millennium challenge for plant scientists

et al. 2018

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Leaf Starch Turnover Occurs in Long Days and in Falling Light at the End of the Day

Cited by 82 publications

References 74 publications

Multiple circadian clock outputs regulate diel turnover of carbon and nitrogen reserves

Multiple circadian clock outputs regulate diel turnover of carbon and nitrogen reserves

Water relations in silver birch during springtime: How is sap pressurised?

Facing global change: the millennium challenge for plant scientists

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