Magdalena Wiktoria Slawinska (Ruprecht-Karls-Universität Heidelberg)
(A) Comparison of Arabidopsis-like stoma and graminoid B. distachyon stoma; (i) Arabidopsis-like stoma with an ellipse pore shape and (ii) hexagonal B. distachyon stoma, with traits measured: guard cell length (GCL), pore length (PL), pore width (PW), guard-cell width at the center of the stoma (GCWC), stomatal width at the apices (WA) and pore depth (l); (iii) pore area hand-traced (red), pore geometrically defined as an ellipse (orange) or a rectangle (blue). (B) Morphology of wild-type B. distachyon and bdpox-1 stomata with elongated guard cells. Orthogonals of the central part (blue), apex (purple) and the longitudinal axis (yellow) of wild-type B. distachyon stoma (i) and bdpox-1 stoma with elongated GCs (ii). Scale bars, 10 µM. (C) Confocal microscopy image of fusicoccin-treated open wild-type B. distachyon (i) and bdpox-1 stoma with orthogonal section of the central part.
Magdalena Slawinska's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Ruprecht-Karls-Universität Heidelberg in the year 2022
Title: Exploring the impact of stomatal morphology on gas exchange
We adjusted the formula to calculate anatomical maximum stomatal conductance (gsmax , defined as the quantitative rate of how much water vapour or CO2 goes through stomata [mol sec-1 m-2]) for grass stomatal morphology and proposed a cell-wall modifying role for the peroxidase BdPOX to restrict guard cell elongation and guarantee water-use efficient stomatal movements.
Stomata are epidermal breathing pores allowing plants to regulate carbon assimilation and water loss. In grasses, unique graminoid stomatal morphology has been shown to enable faster stomatal movements, larger pore apertures and improved water use efficiency in comparison with other stomatal morphologies. Here, we attempted to deepen our understanding of how guard cells’ length in grass stoma contributes to water-use efficient stomatal movements and improved stomatal performance, and identify the mechanism of action of BdPOX peroxidase in the elongation of guard cells. We (i) adjusted anatomical gsmax formula for graminoid morphology and compared anatomical gsmax estimation in wild-type B. distachyon (WT) and bdpox-1 mutant, (ii) performed high resolution confocal microscopy of wild-type B. distachyon and bdpox-1 stomata to provide foundations for building a mechanical model of B. distachyon stomata to understand if guard cells length affects stomatal movements, and (iii) analysed phenolic compounds autofluorescence and ROS levels in cell walls in guard cells of wild-type B. distachyon and bdpox-1 mutant to elucidate the mechanism of action of BdPOX peroxidase. We show physiological gsmax in B. distachyon can be reliably estimated by calculating the theoretical anatomical gsmax. Moreover, we present an optimized guard cells staining protocol allowing obtaining high-resolution confocal stacks suitable for mechanical modeling of grass stomata in different genotypes. Finally, we propose that BdPOX acts at the end of stomatal development in B. distachyon by depositing phenolic compounds, leading to restriction of guard cells elongation.
The adjusted formula to calculate gsmax for grass stomata was published (DOI: 10.1017/qpb.2021.19) and the findings on BdPOX’s role can be found as a preprint (DOI: 10.1101/2022.07.03.498611).
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Magdalena Slawinska conducted this work at the Centre for Organismal Studies (COS) in the working group of Dr. Michael Raissig