Convergent xylem widening among organs across diverse woody seedlings

Abstract

Summary Xylem conduit diameter (Dmax) of woody angiosperm adults scales with plant size and widens from the stem apex downwards. We hypothesized that, notwithstanding relative growth rate (RGR), growth form or leaf habit, woody seedling conduit Dmax scales linearly with plant size across species; this scaling should be applicable to all vegetative organs, with consistent conduit widening from leaf via stem to main root and coupling with whole‐leaf area and whole‐stem xylem area. To test these hypotheses, organ‐specific xylem anatomy traits and size‐related traits in laboratory‐grown seedlings were analyzed across 55 woody European species from cool‐temperate and Mediterranean climates. As hypothesized, conduit Dmax of each organ showed similar scaling with plant size and consistent basipetal widening from the leaf midvein via the stem to the main root across species, independently of growth form, RGR and leaf habit. We also found a strong correlation between Dmax and average leaf area, and between stem xylem area and whole‐plant leaf area. We conclude that seedlings of ecologically wide‐ranging woody species converge in their allometric scaling of conduit diameters within and across plant organs. These relationships will contribute to modeling of water transport in woody vegetation that accounts for the whole life history from the trees’ regeneration phase to adulthood.

Allometric co‐variation of xylem and stomata across diverse woody seedlings

“…(stem) and that the remarkably tight co-variation in vessel diameter between different organs (especially between leaf and stem) (Zhong et al, 2019). When we now combine all three findings, we can conclude that natural selection has led to rather tight regulation of waterrelated architecture featuring similar size-driven variation across seedlings of diverse woody species, both for single leaves and entire plant individuals.…”

“…These findings provide empirical support for, as well as a better functional understanding of the xylem structure models and have broad implications for integrating xylem widening (Anfodillo et al, 2006;Olson et al, 2014;Zhong et al, 2019) Table 1 [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…We examined relations between xylem dimensions (Zhong et al, 2019) and stomatal dimensions of these seedlings both at whole-plant level and at leaf level. Specifically, this study presents, for the first time, the allometric scaling relationships at two scales: (a) between stem xylem cross-sectional area (as well as stem xylem conductance area) and total stomatal area at the whole-plant level, and (b) between leaf mid-vein xylem area and leaf total stomatal area at single-leaf level.…”

Investigating Effects of Bordered Pit Membrane Morphology and Properties on Plant Xylem Hydraulic Functions—A Case Study from 3D Reconstruction and Microflow Modelling of Pit Membranes in Angiosperm Xylem

“…Given that a strong positive correlation exists between xylem embolism resistance and pit membrane thickness [4], if larger vessels are more vulnerable to xylem embolism, one would expect larger vessels should have thinner pit membranes. Although there is convergent vessel widening from tree top to tree base [32,33], and vessel diameter tends to increase radially from the pith to the bark [30], no general agreement has been achieved on whether larger or smaller conduits are more vulnerable to xylem embolism [34], which might yield conflicting findings on pit membrane thickness from different studied tree species as mentioned above. Therefore, multiple tree species are needed to further explore the axial and radial variation of pit membrane thickness.…”

Alfalfa Growth under Changing Environments: An Overview

“…This science was established and developed many hundreds of years ago and still receives a large amount of effort, including original articles, reviews and books (examples of recent books: Beck 2010; Maiti et al 2012;Steeves and Sawhney 2017;Crang et al 2018). These efforts have real potential or importance in different fields, in particular the environmental and agricultural sciences (e.g., Carriquí et al 2019;Farooq et al 2019;Lisztes-Szabó 2019;Zhong et al 2019). Therefore, understanding of the plant's anatomy may guarantee sound knowledge of the plant's structural components and the function of each component.…”