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Primary cell wall composition of bryophytes and charophytes
1The Edinburgh Cell Wall Group, Institute of Cell and Molecular Biology, The University of Edinburgh, David Rutherford Building, Mayfield Road, Edinburgh EH9 3JH, UK.
Annals of Botany
|December 24, 2002
Summary
Xyloglucan is present in all land plants, but absent in closely related green algae. Bryophytes and charophytes have higher levels of uronic acids and mannose in their primary cell walls (PCW) than vascular plants.
Area of Science:
- Plant Biology
- Evolutionary Botany
- Biochemistry
Background:
- Plant primary cell walls (PCW) are crucial for plant structure and development.
- Understanding PCW composition evolution provides insights into plant adaptation and diversification.
- Comparative analysis of PCW components across diverse plant lineages is key to tracing evolutionary events.
Purpose of the Study:
- To investigate major differences in primary cell wall (PCW) components among non-vascular plant taxa and compare them with vascular plants.
- To determine the presence or absence of key polysaccharides like xyloglucan and mixed-linkage glucan (MLG) across different plant groups.
- To analyze the content of uronic acids and mannose in PCWs of various plant species to understand evolutionary trends.
Main Methods:
- Enzymatic digestion (driselase, xyloglucan-specific endoglucanase, cellulase, licheninase) of PCW-rich material.
- Acid hydrolysis of PCW-rich material to analyze polysaccharide composition.
- Identification and quantification of specific sugar units (isoprimeverose, glucuronic acid, galacturonic acid, mannose) using analytical techniques.
Main Results:
- Xyloglucan was detected in all tested land plants (hornworts, mosses, liverworts, vascular plants) but absent in charophycean green algae.
- Bryophytes and charophytes exhibited higher concentrations of uronic acids (glucuronic acid, galacturonic acid) and mannose in their PCWs compared to vascular plants.
- An unusual glucuronic acid-galactose repeat unit was found in the hornwort Anthoceros; MLG was absent in algae and bryophytes but present in Ulva lactuca and Lophocolea bidentata.
Conclusions:
- Major evolutionary events in plant history are associated with significant changes in PCW composition.
- The acquisition of xyloglucan likely provided a pre-adaptive advantage for land colonization by early plants.
- Distinct differences in PCW composition between charophytes, bryophytes, and vascular plants highlight key evolutionary transitions.