Mechanical properties and structure-function trade-offs in secondary xylem of young roots and stems
Language English Country Great Britain, England Media print
Document type Journal Article, Research Support, Non-U.S. Gov't, Review
PubMed
31301134
DOI
10.1093/jxb/erz286
PII: 5531920
Knihovny.cz E-resources
- Keywords
- Axial parenchyma, fibres, mechanical function, rays, structural bending modulus, structural torsional modulus, trade-off, wood,
- MeSH
- Wood chemistry growth & development MeSH
- Plant Roots chemistry growth & development MeSH
- Magnoliopsida chemistry growth & development MeSH
- Plant Stems chemistry growth & development MeSH
- Xylem chemistry MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Bending and torsional properties of young roots and stems were measured in nine woody angiosperms. The variation in mechanical parameters was correlated to wood anatomical traits and analysed with respect to the other two competing functions of xylem (namely storage and hydraulics). Compared with stems, roots exhibited five times greater flexibility in bending and two times greater flexibility in torsion. Lower values of structural bending and structural torsional moduli (Estr and Gstr, respectively) of roots compared with stems were associated with the presence of thicker bark and a greater size of xylem cells. Across species, Estr and Gstr were correlated with wood density, which was mainly driven by the wall thickness to lumen area ratio of fibres. Higher fractions of parenchyma did not translate directly into a lower wood density and reduced mechanical stiffness in spite of parenchyma cells having thinner, and in some cases less lignified, cell walls than fibres. The presence of wide, partially non-lignified rays contributed to low values of Estr and Gstr in Clematis vitalba. Overall, our results demonstrate that higher demands for mechanical stability in self-supporting stems put a major constraint on xylem structure, whereas root xylem can be designed with a greater emphasis on both storage and hydraulic functions.
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