The cell walls of different Chara species are characterized by branched galactans rich in 3‐O‐methylgalactose and absence of AGPs

• DOI: 10.1111/ppl.13989
• Publication Date: 2023-08-23T07:42:27Z
• Authors: Lukas Pfeifer; Kim‐Kristine Mueller; Jon Utermöhlen; Felicitas Erdt; Jean Bastian Just...; Hendrik Schubert; Birgit Classen
• Keywords: Chara

Streptophyte algae are the closest relatives to land plants; their latest common ancestor performed most drastic adaptation in plant evolution around 500 million years ago: conquest of land. Besides other adaptations, this step required changes cell wall composition. Current knowledge on walls streptophyte and especially presence arabinogalactan-proteins (AGPs), important signalling molecules all plants, is limited. To get deeper insights into algae, Charophyceae, we sequential extractions four Chara species. The three species globularis, subspinosa tomentosa revealed comparable compositions, with pectins, xylans xyloglucans, whereas aspera stood out higher amounts uronic acids pectic fractions lack reactivity antibodies binding xylan- xyloglucan epitopes. Search for AGPs Nitellopsis obtusa galactans pyranosidic galactose 1,3-, 1,6- 1,3,6-linkage, which typical galactan motifs AGPs. A unique feature these branched was high portions 3-O-methylgalactose. Only contained substantial arabinose bioinformatic search prolyl-4-hydroxylases, involved biosynthesis AGPs, one possible functional sequence genome braunii, but no hydroxyproline could be detected or obtusa. We conclude that plants absent, at least members Charophyceae.