Defoliation-induced compensatory transpiration is compromised in<i>SUT4</i>-RNAi<i>Populus</i>

Frost, Christopher J.; Tsai, Chung‐Jui

doi:10.1101/2020.01.13.905406

Cited by 3 publications

(11 citation statements)

References 49 publications

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“…One possible outcome is greater turgor and reduced contact area between KD cells for intercellular plasmodesmatal connections and symplasmic flow, in accordance with principals reviewed in Schulz (2015) . Consistent with the possibility of limited export, growth of PtaSUT4 -KD plants was more reduced than that of WT plants when photosynthetic capacity was reduced by partial defoliation ( Harding et al. 2020 ).…”

Section: Discussionmentioning

confidence: 73%

“…How this could happen in light of the symplasmic continuum between leaf mesophyll and export phloem is still a matter for speculation. We have previously reported increased cellular sphericity in the mesophyll of KD leaves along with a higher bulk modulus of elasticity compared to WT leaves ( Harding et al. 2020 ).…”

Section: Discussionmentioning

confidence: 93%

“…2019 ). Whether hydrostatic tension was weaker in KO than WT leaves before excision, thus delaying or otherwise inhibiting phloem sealing in KO leaves after their excision, was not determined, but hydrostatic behaviors of PtaSUT4 -KD and WT leaves have been found to differ ( Harding et al. 2020 ).…”

Section: Discussionmentioning

confidence: 99%

“…2012 , Xue et al. 2016 , Harding et al. 2020 ) and two KO lines were equally spaced but randomly positioned on a floor area of 6 m × 3 m. Plants were grown to ∼1.0–1.5 m in height with daily drip irrigation, supplemental light emitting diode (LED) lighting to maintain a 14-h photoperiod with a photon flux density in the upper canopy of ∼600 μmol photons m −2 s −1 on overcast days, but in mid-lower canopy, only 150 μmol on overcast days, with temperature control to prevent night-time temperatures from dropping below 18°C and to keep daytime temperatures above 30°C on overcast days.…”

Section: Methodsmentioning

confidence: 99%

“…2012 ). PtaSUT4 -KD poplars also exhibit greater leaf water retention than WT leaves under increasing pressure ( Harding et al. 2020 ).…”

Section: Introductionmentioning

confidence: 99%

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Tonoplast Sucrose Trafficking Modulates Starch Utilization and Water Deficit Behavior in Poplar Leaves

Tuma

Aulakh

Ortega

et al. 2022

Plant and Cell Physiology

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Leaf osmotic adjustment by the active accrual of compatible organic solutes (e.g., sucrose) contributes to drought tolerance throughout the plant kingdom. In Populus tremula x alba, PtaSUT4 encodes a tonoplast sucrose-proton symporter whose down-regulation by chronic mild drought or transgenic manipulation is known to increase leaf sucrose and turgor. While this may constitute a single drought tolerance mechanism, we now report that other adjustments which can occur during a worsening water deficit are damped when PtaSUT4 is constitutively down-regulated. Specifically, we report that starch use and leaf relative water content (RWC) dynamics were compromised when plants with constitutively down-regulated PtaSUT4 were subjected to a water deficit. Leaf RWC decreased more in wild type and vector control lines than in transgenic PtaSUT4-RNAi or CRISPR-knockout (KO) lines during the onset of an acute water deficit, even though leaf water loss was the same in all lines. The control line RWC decrease was accompanied by increased PtaSUT4 transcript levels and a mobilization of sucrose from the mesophyll-enriched leaf lamina into the midvein. The findings suggest that changes in SUT4 expression can increase turgor or decrease RWC as different tolerance mechanisms to reduced water availability. Evidence is presented that PtaSUT4-mediated sucrose partitioning between vacuole and cytosol is important not only for overall sucrose abundance and turgor, but also for reactive oxygen species (ROS) and antioxidant dynamics. Interestingly, the reduced capacity for accelerated starch breakdown under worsening water-deficit conditions was correlated with reduced ROS in the RNAi and KO lines. A role for PtaSUT4 in the orchestration of ROS, antioxidant, starch utilization and RWC dynamics during water stress, and its importance in trees especially, with their high hydraulic resistances, is considered.

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Section: Discussionmentioning

confidence: 73%

Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…2012 ). PtaSUT4 -KD poplars also exhibit greater leaf water retention than WT leaves under increasing pressure ( Harding et al. 2020 ).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tonoplast Sucrose Trafficking Modulates Starch Utilization and Water Deficit Behavior in Poplar Leaves

Tuma

Aulakh

Ortega

et al. 2022

Plant and Cell Physiology

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RNA Interference (RNAi): A Genetic Tool to Manipulate Plant Secondary Metabolite Pathways

Pathak

Patel

Joshi

2021

RNA-Based Technologies for Functional Genomics in Plants

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Perturbation of tonoplast sucrose transport alters carbohydrate utilization for seasonal growth and defense metabolism in coppiced poplar

Tuma,

Nyamdari,

Hsieh

et al. 2023

Preprint

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Non-structural carbohydrate reserves of stems and roots underpin overall tree fitness as well as productivity under short-rotation management practices such as coppicing for bioenergy. While both sucrose and starch comprise the predominant carbohydrate reserves ofPopulus, utilization is understood primarily in terms of starch turnover. The tonoplast sucrose transport protein SUT4 modulates sucrose export to distant sinks, but the possibility of its involvement in sink tissue carbohydrate remobilization has not been explored. Here, we usedPtaSUT4-knockout mutants ofPopulus tremula × alba(INRA 717-1B4) in winter and summer glasshouse coppicing experiments to strain carbon demand and test for SUT4 involvement in reserve utilization. We show that epicormic bud emergence was delayed and subsequent growth reduced insut4mutants following winter but not summer coppicing. Reserve depletion during post-coppice regrowth was not impaired in thesut4mutants under winter or summer glasshouse conditions. Interestingly, xylem hexose increased during post-coppice growth exclusively in the winter when osmoprotection is critical, and the increase was attenuated insut4mutants. Accrual of abundant defense metabolites, including salicinoids, chlorogenic acids, and flavonoid products was prioritized in the summer, but conspicuously lower insut4mutants than controls. Together, our results point to shifting priorities for SUT4 function from support for osmoprotection in winter to chemical defense in summer. Delayed bud release and growth following winter but not summer coppicing in thesut4mutants demonstrate the importance of SUT4 in modulating trade-offs between growth and the other priorities during reserve utilization inPopulus.

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Defoliation-induced compensatory transpiration is compromised inSUT4-RNAiPopulus

Cited by 3 publications

References 49 publications

Tonoplast Sucrose Trafficking Modulates Starch Utilization and Water Deficit Behavior in Poplar Leaves

Tonoplast Sucrose Trafficking Modulates Starch Utilization and Water Deficit Behavior in Poplar Leaves

RNA Interference (RNAi): A Genetic Tool to Manipulate Plant Secondary Metabolite Pathways

Perturbation of tonoplast sucrose transport alters carbohydrate utilization for seasonal growth and defense metabolism in coppiced poplar

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