Biology Reference
In-Depth Information
Fig. 6. Lignins in lycophytes. (A) Detail from Selaginella martensii frond.
(B) Ma¨ le staining of transverse sections of Selaginella stems. Red and brown colours
indicate the presence of S and G lignins, respectively. Bars
¼
300
m
m. (C) Two-
dimensional HSQC NMR spectra of acetylated cellulolytic enzyme lignins from
Selaginella whole stems, revealing the presence of syringyl lignins. C box is taken
from
Weng et al. (2011)
, reproduced with permission from ASPB.
derivatives have not been found in the extinct arborescent lycophyte Sigil-
laria ovata (
Logan and Thomas, 1987
). However, lignins, and more specifi-
cally, syringyl lignins, were reported by chemical degradative methods in the
herbaceous Isoetes and Huperzia (
Towers and Gibbs, 1953; Towers and
Maass, 1965
) and, more conclusively, by chemical depolymerizing methods
including thioacidolysis in Selaginella and Isoetes (
Espi
˜
eira et al., 2011
).
The presence of S units in some lycopods is well known and has been
associated with the existence in the xylem of angiosperm-like vessels
(
Schneider and Carlquist, 2000
). Selaginella is a representative of the Lyco-
podiophyta and one of the earliest divergent clades of extant vascular plants
