Development, Structure, and Function of Torus–Margo Pits in Conifers, Ginkgo and Dicots

Dute, Roland R.

doi:10.1007/978-3-319-15783-2_3

Cited by 13 publications

(17 citation statements)

References 55 publications

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“…The slightly negatively charged cellulose fibres may repel each other and are more loosely arranged in the centre than near the edges (Zhang et al ., 2016), where the fibres are firmly anchored into the pectin‐rich annulus and primary wall. Although the orientation of microfibrils may not be completely random and appears to be directed by a dual guidance mechanism (Chan & Coen, 2020), it seems unlikely that more cellulose fibrils are deposited in the centre than near the annulus, in contrast to torus‐bearing angiosperms (Dute, 2015).…”

Section: Discussionmentioning

confidence: 99%

Pore constrictions in intervessel pit membranes provide a mechanistic explanation for xylem embolism resistance in angiosperms

et al. 2021

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Embolism spreading in angiosperm xylem occurs via mesoporous pit membranes between vessels. Here, we investigate how the size of pore constrictions in pit membranes is related to pit membrane thickness and embolism resistance.Pit membranes were modelled as multiple layers to investigate how pit membrane thickness and the number of intervessel pits per vessel determine pore constriction sizes, the probability of encountering large pores, and embolism resistance. These estimations were complemented by measurements of pit membrane thickness, embolism resistance, and number of intervessel pits per vessel in stem xylem (n = 31, 31 and 20 species, respectively).The modelled constriction sizes in pit membranes decreased with increasing membrane thickness, explaining the measured relationship between pit membrane thickness and embolism resistance. The number of pits per vessel affected constriction size and embolism resistance much less than pit membrane thickness. Moreover, a strong relationship between modelled and measured embolism resistance was observed.Pore constrictions provide a mechanistic explanation for why pit membrane thickness determines embolism resistance, which suggests that hydraulic safety can be uncoupled from hydraulic efficiency. Although embolism spreading remains puzzling and encompasses more than pore constriction sizes, angiosperms are unlikely to have leaky pit membranes, which enables tensile transport of water.

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Section: Discussionmentioning

confidence: 99%

Pore constrictions in intervessel pit membranes provide a mechanistic explanation for xylem embolism resistance in angiosperms

et al. 2021

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“…; Schmitz et al . ) and diversity in pit membrane characteristics (Dute ; Jacobsen et al . ; Li et al .…”

Section: Xylem Functional Traits and The Safety–efficiency Tradeoffmentioning

confidence: 99%

Conflicting demands on angiosperm xylem: Tradeoffs among storage, transport and biomechanics

Pratt

Jacobsen

2016

Plant Cell & Environment

160

154

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The secondary xylem of woody plants transports water mechanically supports the plant body and stores resources. These three functions are interdependent giving rise to tradeoffs in function. Understanding the relationships among these functions and their structural basis forms the context in which to interpret xylem evolution. The tradeoff between xylem transport efficiency and safety from cavitation has been carefully examined with less focus on other functions, particularly storage. Here, we synthesize data on all three xylem functions in angiosperm branch xylem in the context of tradeoffs. Species that have low safety and efficiency, examined from a resource economics perspective, are predicted to be adapted for slow resource acquisition and turnover as characterizes some environments. Tradeoffs with water storage primarily arise because of differences in fibre traits, while tradeoffs in carbohydrate storage are driven by parenchyma content of tissue. We find support for a tradeoff between safety from cavitation and storage of both water and starch in branch xylem tissue and between water storage capacity and mechanical strength. Living fibres may facilitate carbohydrate storage without compromising mechanical strength. The division of labour between different xylem cell types allows for considerable functional and structural diversity at multiple scales.

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“…A granular appearance of the intervessel pit membrane was found in Mallotus japonicus using cryo-SEM, but whether this is characteristic of the native status is unknown (Roth-Nebelsick et al 2010). Moreover, angiosperm pit membranes are typically homogeneous, i.e., the actual pit membrane has a constant thickness, although some torus-bearing pit membranes occur in angiosperms (Jansen et al 2004;Dute et al 2012;Dute 2015).…”

Section: Introductionmentioning

confidence: 99%

Intervessel Pit Membrane Thickness as a Key Determinant of Embolism Resistance in Angiosperm Xylem

Lens

Espino³

et al. 2016

IAWA J

210

218

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Pit membranes in bordered pits between neighbouring vessels play a major role in the entry of air-water menisci from an embolised vessel into a water-filled vessel (i.e., air-seeding). Here, we investigate intervessel pit membrane thickness (TPM) and embolism resistance (P50, i.e., the water potential corresponding to 50% loss of hydraulic conductivity) across a broad range of woody angiosperm species. Data on TPM and double intervessel wall thickness (TVW) were compiled based on electron and light microscopy. Fresh material that was directly fixated for transmission electron microscopy (TEM) was investigated for 71 species, while non-fresh samples were frozen, stored in alcohol, or air dried prior to TEM preparation for an additional 60 species. TPM and P50 were based on novel observations and literature. A strong correlation between TPM and P50 was found for measurements based on freshly fixated material (r = 0.78, P >0.01, n = 37), and between TPM and TVW (r = 0.79, P >0.01, n = 59), while a slightly weaker relationship occurred between TVW and P50 (r = 0.40, P >0.01, n = 34). However, non-fresh samples showed no correlation between TPM and P50, and between TPM and TVW. Intervessel pit membranes in non-fresh samples were c.28% thinner and more electron dense than fresh samples. Our findings demonstrate that TPM measured on freshly fixated material provides one of the strongest wood anatomical correlates of droughtinduced embolism resistance in angiosperms. Assuming that cellulose microfibrils show an equal spatial density, TPM is suggested to affect the length and the shape of intervessel pit membrane pores, but not the actual pore size. Moreover, the shrinking effect observed for TPM after dehydration and frost is associated with an increase in microfibril density and porosity, which may provide a functional explanation for embolism fatigue.

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Development, Structure, and Function of Torus–Margo Pits in Conifers, Ginkgo and Dicots

Cited by 13 publications

References 55 publications

Pore constrictions in intervessel pit membranes provide a mechanistic explanation for xylem embolism resistance in angiosperms

Pore constrictions in intervessel pit membranes provide a mechanistic explanation for xylem embolism resistance in angiosperms

Conflicting demands on angiosperm xylem: Tradeoffs among storage, transport and biomechanics

Intervessel Pit Membrane Thickness as a Key Determinant of Embolism Resistance in Angiosperm Xylem

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