Phycocolloid chemistry as a taxonomic indicator of phylogeny in the Gigartinales, Rhodophyceae: A review and current developments using Fourier transform infrared diffuse reflectance spectroscopy

The morphologically similar sporophytic and gametophytic plants of Chondrus crispus Stackhouse were examined and it was shown that the former contain λ-carrageenan. The gametophytes contain ϰ- and two additional carrageenans which are KCl-soluble and may comprise up to 25% of the total carrageenan. After alkaline modification, these KCl-soluble components were separated into a gel and a soluble carrageenan. The gel was indistinguishable from ϰ-carrageenan and presumably was derived from μ-carrageenan while the KCl-soluble fraction possessed a unique infrared spectrum easily distinguished from alkali-modified λ-carrageenan. This appears to represent a third carrageenan in the gametophytes.Our observations suggest that the biologically separate plants of C. crispus exhibit distinctive patterns of sulfation of their galactans. The sporophytes add SO4 (2-) at C2 of the precursor, whereas the gametophytes appear to add it principally at the available C4 positions. Both types of plant are capable of sulfating at C6 of the 4-linked galactose unit.