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Manipulating phloem transport affects wood formation but not local nonstructural carbon reserves in an evergreen conifer
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  • Tim Rademacher,
  • Patrick Fonti,
  • James LeMoine,
  • Marina Fonti,
  • David Basler,
  • Yizhao Chen,
  • Andrew Friend,
  • Bijan Seyednasrollah,
  • Annemarie Eckes-Shephard,
  • Andrew Richardson
Tim Rademacher
Harvard University
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Patrick Fonti
Swiss Federal Research Institute WSL
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James LeMoine
Northern Arizona University
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Marina Fonti
WSL
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David Basler
Harvard University
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Yizhao Chen
University of Cambridge
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Andrew Friend
University of Cambridge
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Bijan Seyednasrollah
Northern Arizona University
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Annemarie Eckes-Shephard
University of Cambridge
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Andrew Richardson
Northern Arizona University
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Abstract

How variations in carbon supply affect wood formation remains poorly understood in particular in mature forest trees. To elucidate how carbon supply affects carbon allocation and wood formation, we attempted to manipulate carbon supply to the cambial region by phloem girdling and compression during the mid- and late-growing season and measured effects on structural development, CO2 efflux, and nonstructural carbon reserves in stems of mature white pines. Wood formation and stem CO2 efflux varied with location relative to treatment (i.e., above or below the restriction). We observed up to twice as many tracheids formed above versus below the treatment after the phloem transport manipulation, whereas cell-wall area decreased only slightly below the treatments, and cell size did not change relative to the control. Nonstructural carbon reserves in the xylem, needles, and roots were largely unaffected by the treatments. Our results suggest that low and high carbon supply affects wood formation, primarily through a strong effect on cell proliferation, and respiration, but local nonstructural carbon concentrations appear to be maintained homeostatically. This contrasts with reports of a decoupling of source activity and wood formation at the whole-tree or ecosystem level, highlighting the need to better understand organ-specific responses, within-tree feedbacks, as well as phenological and ontological effects on sink-source dynamics.

Peer review status:ACCEPTED

10 May 2021Submitted to Plant, Cell & Environment
11 May 2021Submission Checks Completed
11 May 2021Assigned to Editor
15 May 2021Review(s) Completed, Editorial Evaluation Pending
15 May 2021Editorial Decision: Revise Minor
17 May 20211st Revision Received
17 May 2021Submission Checks Completed
17 May 2021Assigned to Editor
18 May 2021Review(s) Completed, Editorial Evaluation Pending
18 May 2021Editorial Decision: Accept