Tag Archives: cell wall (primary)

Hemicellulose evolution in monilophytes (Research in Context)

Hemicellulose evolution in monilophytes (Research in Context)

Hemicellulose evolution in monilophytes (Research in Context)

The Equisetopsida emerged in the Upper Devonian (>370 mya), and Equisetum (horsetails) may be the oldest surviving vascular plant genus. Horsetails and the Poales are the only plants possessing the hemicellulose (1->3, 1->4)-b-d-glucan (MLG). Xue and Fry show that variation has occurred in MLG structure during horsetail diversification, and that E. bogotense (the earliest-diverging species) has MLG composed almost solely of an ancestral tetrasaccharide repeat-unit, G4G4G3G, whereas other species in both subgenera (Equisetum and Hippochaete) have additional di- and trisaccharide repeats. Quantitatively, xyloglucan is down-played in monilophyte species rich in MLG or mannans. They conclude that plants have ‘experimented’ extensively with hemicellulose structures and proportions during evolution.