Evolution of xylem lignification and hydrogel transport regulation.
In vascular plants, the polysaccharide-based walls of water-conducting cells are strengthened by impregnation with the polyphenolic polymer lignin. The fine-scale patterning of lignin deposition in water-conducting cells is shown here to vary phylogenetically across vascular plants. The extent to which water transport in xylem cells can be modified in response to changes in the ionic content of xylem sap also is shown to vary in correlation with variation in lignification patterns, consistent with the proposed mechanism for hydraulic response through size change of middle-lamella pectins. This covariation suggests that the fine-scale distribution of hydrophilic polysaccharides and hydrophobic lignin can affect hydraulic as well as mechanical properties, and that the evolutionary diversification of vascular cells thus reflects biochemical as well as morphological innovations evolved to fulfill opposing cell functions of transport and structural support.
Boyce
C Kevin
CK
Department of Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA. ckboyce@uchicago.edu
Zwieniecki
Maciej A
MA
Cody
George D
GD
Jacobsen
Chris
C
Wirick
Sue
S
Knoll
Andrew H
AH
Holbrook
N Michele
NM
D005075:Biological Evolution; D001692:Biological Transport; D007477:Ions / Q000378:metabolism; D008031:Lignin / Q000378:metabolism*; D010802:Phylogeny; D018515:Plant Leaves / Q000033:anatomy & histology / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D018547:Plant Stems / Q000033:anatomy & histology / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism*
D007477:Ions; D008031:Lignin