Structural Motifs of Syringyl Peroxidases Are Conserved during Angiosperm Evolution

Abstract

The most distinctive variation in the monomer composition of lignins in vascular land plants is that between the two main groups of seed plants. Thus, whereas gymnosperm (softwood) lignins are typically composed of guaiacyl (G) units, angiosperm (hardwood) lignins are largely composed of similar levels of G and syringyl (S) units. However, there are some studies that suggest that certain angiosperm peroxidases are unable to oxidize sinapyl alcohol, and a coniferyl alcohol shuttle has been proposed for oxidizing S units during the biosynthesis of lignins. With this in mind, a screening of the presence of S peroxidases in angiosperms (including woody species and forages) was performed. Contrarily to what might be expected, the intercellular washing fluids from lignifying tissues of 25 woody, herbaceous, and shrub species, belonging to both monocots and dicotyledons, all showed both S peroxidase activities and basic peroxidase isoenzymes analogous, with regard the isoelectric point, to the Zinnia elegans basic peroxidase isoenzyme, the only S peroxidase that has been fully characterized. These results led to the protein database in the search for homologies between angiosperm peroxidases and a true eudicot S peroxidase, the Z. elegans peroxidase. The findings showed that certain structural motifs of S peroxidases are conserved within the first 15 million years of angiosperm history, because they are found in peroxidases from the two major lineages of flowering plants, eumagnoliids and eudicotyledons, of note being the presence of these peroxidases in Amborella and Nymphaeales, which represent the first stages of angiosperm evolution. These phylogenetic studies also suggest that guaiacyl peroxidases apparently constitute the most "evolved state" of the plant peroxidase family evolution.

Genetic Assessment of Traits and Genetic Relationship in Blackgram (Vigna mungo) Revealed by Isoenzymes

“…It has been widely used to establish phylogenetic relationships among taxa, genetic markers for hybrid confirmation, and for convenient screening of seedlings with target characters (Bleeker and Hurka 2001;Upadhyay et al 2002;Fromm and Hattemer 2003;Stecconi et al 2004;Yu et al 2005;Vasylenko et al 2006). Isoenzymic variations have also been extensively used as genetic markers for evolutionary studies (Gomez Ros et al 2007), characterization of species and cultivars (Nakonechnaia et al 2007;Curtu et al 2007), and genetic studies in plants (Yu et al 2005;Roy et al 2006;Grundmann et al 2007). Mittal et al (1993) studied eight Vigna radiata cultivars for enzyme activities and concluded that there was a positive correlation of acid phosphatase with 100 seed weight but a negative correlation with number of pods per plant and seed yield.…”

Lignification and Lignin Manipulations in Conifers

“…Laccases have also been proposed to have a role in late stages of lignification where H 2 O 2 is essentially excluded from penetrating the hydrophobic, lignified cell wall environment (Gavnholt and Larsen, 2002). These speculations make it quite obvious that we lack detailed knowledge of how peroxidases and laccases share their role in lignin polymerisation, a situation complicated by the differing substrate preferences that laccases and peroxidases can have (Deighton et al, 1999;Gó mez Ros et al, 2007;Marjamaa et al, 2006;Tsutsumi et al, 1998). Recent observations have shown that laccases are among the most abundant proteins in lignin-rich compression wood (Mast et al, 2010), which suggests an important role for laccases in lignin polymerisation in conifers.…”

Distribution of lignin monomers and the evolution of lignification among lower plants

“…2007b) and angiosperms (Ros Barceló et al. 2006; Gómez Ros et al. 2007a) and, as in the above‐mentioned cases, it was limited to vascular tissues.…”