| ||||||||||||||||||||

Evolution and the primary cell wall
Popper and Fry (pp. 1-12) investigate the composition of the primary cell wall (PCW) of lower land plants and charophytes (their closest living relatives). Charophyte and bryophyte PCWs were found to differ from those of euphyllophytes. However, xyloglucan (a major hemicellulose in all land plants, including bryophytes) was absent from PCWs of charophytes. Variation in PCW composition may be related to ecological pressures experienced during terrestrialization.
| ||||||||||||||||||||