The Structure and Function of Xylem in Seed-Free Vascular Plants: An Evolutionary Perspective

Pittermann, Jarmila; Watkins, James E.; Cary, Katharine L.; Schuettpelz, Eric; Brodersen, Craig R.; Smith, Alan Р.; Baer, Alex

doi:10.1007/978-3-319-15783-2_1

Cited by 25 publications

(29 citation statements)

References 137 publications

(236 reference statements)

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“…The small abaxial bundles, however, remain hydraulically isolated from the photosynthetic tissue for much of the length of the frond until all of the bundles merge near the apex of the rachis, similar to the organization and connectivity found in W. fimbriata ( Fig. S2; but see Brodersen et al 2012 andPittermann et al 2015). Therefore, the hydraulic demand by the frond apex is split between five or more vascular bundles, while the pinnae along the lower rachis draw water from only the two large vascular bundles.…”

Section: Discussionmentioning

confidence: 53%

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Embolism spread in the primary xylem of Polystichum munitum: implications for water transport during seasonal drought

Brodersen

Rico

Guenni

et al. 2015

Plant Cell & Environment

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Xylem network structure and function have been characterized for many woody plants, but less is known about fern xylem, particularly in species endemic to climates where water is a limiting resource for months at a time. We characterized seasonal variability in soil moisture and frond water status in a common perennial fern in the redwood understory of a costal California, and then investigated the consequences of drought-induced embolism on vascular function. Seasonal variability in air temperature and soil water content was minimal, and frond water potential declined slowly over the observational period. Our data show that Polystichum munitum was protected from significant drought-induced hydraulic dysfunction during this growing season because of a combination of cavitation resistant conduits (Air-seeding threshold (ASP) = -1.53 MPa; xylem pressure inducing 50% loss of hydraulic conductivity (P50 ) = -3.02 MPa) and a soil with low moisture variability. High resolution micro-computed tomography (MicroCT) imaging revealed patterns of embolism formation in vivo for the first time in ferns providing insight into the functional status of the xylem network under drought conditions. Together with stomatal conductance measurements, these data suggest that P. munitum is adapted to tolerate drier conditions than what was observed during the growing season.

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Section: Discussionmentioning

confidence: 53%

“… and Pittermann et al . ). Therefore, the hydraulic demand by the frond apex is split between five or more vascular bundles, while the pinnae along the lower rachis draw water from only the two large vascular bundles.…”

Section: Discussionmentioning

confidence: 97%

Embolism spread in the primary xylem of Polystichum munitum: implications for water transport during seasonal drought

Brodersen

Rico

Guenni

et al. 2015

Plant Cell & Environment

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“…Light microscopy also revealed an endodermal layer with a Casparian-like strip surrounding the vascular cylinder, analogous to the endodermis found in roots. This endodermal layer is frequently found in fern stipes (Lersten, 1997;Sperry, 2003;Pittermann et al, 2015). In P. triangularis, the endodermal layer remains attached to the shrunken vascular cylinder during desiccation (Fig.…”

Section: Key Stipe Anatomical Traitsmentioning

confidence: 97%

High‐resolution computed tomography reveals dynamics of desiccation and rehydration in fern petioles of a desiccation‐tolerant fern

et al. 2019

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Summary Desiccation‐tolerant (DT) plants can dry past −100 MPa and subsequently recover function upon rehydration. Vascular DT plants face the unique challenges of desiccating and rehydrating complex tissues without causing structural damage. However, these dynamics have not been studied in intact DT plants. We used high resolution micro‐computed tomography (microCT), light microscopy, and fluorescence microscopy to characterize the dynamics of tissue desiccation and rehydration in petioles (stipes) of intact DT ferns. During desiccation, xylem conduits in stipes embolized before cellular dehydration of living tissues within the vascular cylinder. During resurrection, the chlorenchyma and phloem within the stipe vascular cylinder rehydrated before xylem refilling. We identified unique stipe traits that may facilitate desiccation and resurrection of the vascular system, including xylem conduits containing pectin (which may confer flexibility and wettability); chloroplasts within the vascular cylinder; and an endodermal layer impregnated with hydrophobic substances that impede apoplastic leakage while facilitating the upward flow of water within the vascular cylinder. Resurrection ferns are a novel system for studying extreme dehydration recovery and embolism repair in the petioles of intact plants. The unique anatomical traits identified here may contribute to the spatial and temporal dynamics of water movement observed during desiccation and resurrection.

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“…For example, although there have been major breakthroughs in understanding the general principles of stomatal control among ferns (Brodribb et al, 2004(Brodribb et al, , 2009Brodribb & McAdam, 2011), basically nothing is known of the variation of this system among different clades of ferns and its potential role in determining the ecological adaptability of fern species. There are also a number of intriguing studies on fern ecophysiology addressing such aspects as photosynthetic systems (Smith, 2000;Kawai et al, 2003), hydraulic conductivity and xylem anatomy (Watkins et al, 2010;Pittermann et al, 2015), and leaf form (Sessa & Givnish, 2014). Other studies have looked at the ecophysiological limitations of occurrence in single fern species (Saldaña et al, 2007;Testo & Watkins, 2013;Stevens & Emery, 2015) or have compared the ecophysiology of closely related species (Saldaña et al, 2005;Riaño & Briones, 2015;Zier et al, 2015).…”

Section: Options For Future Researchmentioning

confidence: 99%

Elevational diversity patterns as an example for evolutionary and ecological dynamics in ferns and lycophytes

Kessler

Karger

Kluge

2016

J of Sytematics Evolution

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Evolutionary processes such as adaptation, ecological filtering, and niche conservatism involve the interaction of organisms with their environment and are thus commonly studied along environmental gradients. Elevational gradients have become among the most studied environmental gradients to understand large-scale patterns of species richness and composition because they are highly replicated with different combinations of geographical, environmental and historical factors. We here review the literature on using elevational gradients to understand evolutionary processes in ferns. Some phylogenetic studies of individual fern clades have considered elevation in the analysis or interpretation and postulated that fern diversification is linked to the colonization of mountain habitats. Other studies that have linked elevational community composition and hence ecological filtering with phylogenetic community composition and morphological traits, usually only found limited phylogenetic signal. However, these studies are ultimately only correlational, and there are few actual tests of the evolutionary mechanisms leading to these patterns. We identify a number of challenges for improving our understanding of how evolutionary and ecological processes are linked to elevational richness patterns in ferns: i) limited information on traits and their ecological relevance, ii) uncertainties on the dispersal kernels of ferns and hence the delimitation of regional species pools from which local assemblages are recruited, iii) limited genomic data to identify candidate genes under selection and hence actually document adaptation and selection, and iv) conceptual challenges in developing clear and testable hypotheses to how specific evolutionary processes can be linked to patterns in community composition and species richness.

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The Structure and Function of Xylem in Seed-Free Vascular Plants: An Evolutionary Perspective

Cited by 25 publications

References 137 publications

Embolism spread in the primary xylem of Polystichum munitum: implications for water transport during seasonal drought

Embolism spread in the primary xylem of Polystichum munitum: implications for water transport during seasonal drought

High‐resolution computed tomography reveals dynamics of desiccation and rehydration in fern petioles of a desiccation‐tolerant fern

Elevational diversity patterns as an example for evolutionary and ecological dynamics in ferns and lycophytes

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