Pre-chlorotic Mg2+ deficiency impairs guard-cell PSII and leaf gas exchange in Vicia faba
- 1Geisenheim University
Abstract
Magnesium deficiency impairs photosynthesis and transpiration before visible chlorosis, but whether guard cells themselves are affected at this early stage remains unresolved. We combined whole-leaf gas exchange and chlorophyll fluorescence with cell-specific fluorescence measurements of individual guard cell pairs, together with elemental analysis, metabolite profiling, adenosine triphosphate quantification, and proteome profiling of guard cell-enriched material in hydroponically grown Vicia faba. Magnesium deficiency reduced magnesium concentrations in both whole leaves and guard cell-enriched fractions. Under red light, magnesium-deficient leaves showed reduced effective quantum yield of photosystem II, CO2 assimilation, transpiration, and stomatal conductance, whereas intercellular CO2 concentration remained unchanged. Individual guard cell pairs likewise showed reduced effective quantum yield of photosystem II, demonstrating that the early deficiency response extended to guard cells. Electron transport rate and non-photochemical quenching in guard cells were not significantly altered. Only a small set of metabolites in guard cell-enriched material, mainly fatty acids and citrate, responded to magnesium deficiency, whereas ATP abundance and light-induced proton extrusion remained unchanged. In contrast, the guard cell-enriched proteome showed higher abundance of photosynthesis- and translation-related proteins despite reduced guard-cell PSII efficiency. Together, these findings identify guard cells as an early responsive cell type under magnesium deficiency and show that guard-cell photochemistry is impaired before visible chlorosis, alongside reduced whole-leaf carbon gain and water loss.
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BibTeX
@misc{wuebben2026prechlorotic,
title = {{Pre-chlorotic Mg2+ deficiency impairs guard-cell PSII and leaf gas exchange in Vicia faba}},
author = {A. Wuebben and E. Franck and B. L. Franzisky and M. Ishfaq and A. L. Erban and J. Kilian and E. von Roepenack-Lahaye and J. Kopka and M. Stahl and S. Carpentier and C.-M. Geilfus and K. Kampmann},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.07.757235},
url = {https://www.biorxiv.org/content/10.64898/2026.10.07.757235v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - Pre-chlorotic Mg2+ deficiency impairs guard-cell PSII and leaf gas exchange in Vicia faba
AU - A. Wuebben
AU - E. Franck
AU - B. L. Franzisky
AU - M. Ishfaq
AU - A. L. Erban
AU - J. Kilian
AU - E. von Roepenack-Lahaye
AU - J. Kopka
AU - M. Stahl
AU - S. Carpentier
AU - C.-M. Geilfus
AU - K. Kampmann
PY - 2026
DA - 2026/10/07
PB - bioRxiv
DO - 10.64898/2026.10.07.757235
UR - https://www.biorxiv.org/content/10.64898/2026.10.07.757235v1
AB - Magnesium deficiency impairs photosynthesis and transpiration before visible chlorosis, but whether guard cells themselves are affected at this early stage remains unresolved. We combined whole-leaf gas exchange and chlorophyll fluorescence with cell-specific fluorescence measurements of individual guard cell pairs, together with elemental analysis, metabolite profiling, adenosine triphosphate quantification, and proteome profiling of guard cell-enriched material in hydroponically grown Vicia faba. Magnesium deficiency reduced magnesium concentrations in both whole leaves and guard cell-enriched fractions. Under red light, magnesium-deficient leaves showed reduced effective quantum yield of photosystem II, CO2 assimilation, transpiration, and stomatal conductance, whereas intercellular CO2 concentration remained unchanged. Individual guard cell pairs likewise showed reduced effective quantum yield of photosystem II, demonstrating that the early deficiency response extended to guard cells. Electron transport rate and non-photochemical quenching in guard cells were not significantly altered. Only a small set of metabolites in guard cell-enriched material, mainly fatty acids and citrate, responded to magnesium deficiency, whereas ATP abundance and light-induced proton extrusion remained unchanged. In contrast, the guard cell-enriched proteome showed higher abundance of photosynthesis- and translation-related proteins despite reduced guard-cell PSII efficiency. Together, these findings identify guard cells as an early responsive cell type under magnesium deficiency and show that guard-cell photochemistry is impaired before visible chlorosis, alongside reduced whole-leaf carbon gain and water loss.
ER -