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Xylem-phloem hydraulic coupling explains multiple osmoregulatory responses to salt stress.

Publication ,  Journal Article
Perri, S; Katul, GG; Molini, A
Published in: The New phytologist
October 2019

Salinity is known to affect plant productivity by limiting leaf-level carbon exchange, root water uptake, and carbohydrates transport in the phloem. However, the mechanisms through which plants respond to salt exposure by adjusting leaf gas exchange and xylem-phloem flow are still mostly unexplored. A physically based model coupling xylem, leaf, and phloem flows is here developed to explain different osmoregulation patterns across species. Hydraulic coupling is controlled by leaf water potential, ψl , and determined under four different maximization hypotheses: water uptake (1), carbon assimilation (2), sucrose transport (3), or (4) profit function - i.e. carbon gain minus hydraulic risk. All four hypotheses assume that finite transpiration occurs, providing a further constraint on ψl . With increasing salinity, the model captures different transpiration patterns observed in halophytes (nonmonotonic) and glycophytes (monotonically decreasing) by reproducing the species-specific strength of xylem-leaf-phloem coupling. Salt tolerance thus emerges as plant's capability of differentiating between salt- and drought-induced hydraulic risk, and to regulate internal flows and osmolytes accordingly. Results are shown to be consistent across optimization schemes (1-3) for both halophytes and glycophytes. In halophytes, however, profit-maximization (4) predicts systematically higher ψl than (1-3), pointing to the need of an updated definition of hydraulic cost for halophytes under saline conditions.

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Published In

The New phytologist

DOI

EISSN

1469-8137

ISSN

1469-8137

Publication Date

October 2019

Volume

224

Issue

2

Start / End Page

644 / 662

Related Subject Headings

  • Xylem
  • Water
  • Sodium Chloride
  • Salt Stress
  • Plants
  • Plant Transpiration
  • Plant Leaves
  • Plant Biology & Botany
  • Phloem
  • Osmoregulation
 

Citation

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Perri, S., Katul, G. G., & Molini, A. (2019). Xylem-phloem hydraulic coupling explains multiple osmoregulatory responses to salt stress. The New Phytologist, 224(2), 644–662. https://doi.org/10.1111/nph.16072
Perri, Saverio, Gabriel G. Katul, and Annalisa Molini. “Xylem-phloem hydraulic coupling explains multiple osmoregulatory responses to salt stress.The New Phytologist 224, no. 2 (October 2019): 644–62. https://doi.org/10.1111/nph.16072.
Perri S, Katul GG, Molini A. Xylem-phloem hydraulic coupling explains multiple osmoregulatory responses to salt stress. The New phytologist. 2019 Oct;224(2):644–62.
Perri, Saverio, et al. “Xylem-phloem hydraulic coupling explains multiple osmoregulatory responses to salt stress.The New Phytologist, vol. 224, no. 2, Oct. 2019, pp. 644–62. Epmc, doi:10.1111/nph.16072.
Perri S, Katul GG, Molini A. Xylem-phloem hydraulic coupling explains multiple osmoregulatory responses to salt stress. The New phytologist. 2019 Oct;224(2):644–662.
Journal cover image

Published In

The New phytologist

DOI

EISSN

1469-8137

ISSN

1469-8137

Publication Date

October 2019

Volume

224

Issue

2

Start / End Page

644 / 662

Related Subject Headings

  • Xylem
  • Water
  • Sodium Chloride
  • Salt Stress
  • Plants
  • Plant Transpiration
  • Plant Leaves
  • Plant Biology & Botany
  • Phloem
  • Osmoregulation