Kappa-/beta-carrageenans from Australian red algae of the Acrotylaceae (Gigartinales, Rhodophyta)

Abstract

A. Chiovitti, G.T. Kraft, A. Bacic, D.J. Craik, and M.-L. Liao. 2007. Kappa-/beta-carrageenans from Australian red algae of the Acrotylaceae (Gigartinales, Rhodophyta). Phycologia 47: 35–40. DOI: 10.2216/07-10.1

The extracellular polysaccharides of five species of the family Acrotylaceae Schmitz [Acrotylus australis J. Agardh, Amphiplexia hymenocladioides J. Agardh, Antrocentrum nigrescens (Harvey) Kraft & Min-Thein, Hennedya crispa Harvey, and Ranavalona duckerae Kraft] were shown by compositional analyses, ¹³C nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy to be kappa (κ)-/beta (β)-carrageenans in which the κ-carrageenan component is dominant. The uniform presence of κ-/β-carrageenans lends support to the placement of these taxa in the Acrotylaceae based on similarities of procarp structures and highly distinctive centripetally developing gonimoblasts. However, a growing body of 18S rDNA nucleotide-sequence data indicates probable polyphyly for the existing family and the relatively widespread occurrence of κ-/β-carrageenans among a number of families in the order Gigartinales. We regard these carrageenans most likely to represent a pleisiomorphic trait. One current member of the Acrotylaceae, Claviclonium ovatum (Lamouroux) Kraft & Min-Thein, is exceptional in producing a nearly idealized 6′-O-methylated iota (ι)-carrageenan rather than κ-/β-carrageenan. This is a feature more akin to the distinctive, highly methylated carrageenans of the Areschougiaceae, a family only distantly related to the Acrotylaceae in molecular trees and which exhibits a substantially different mode of carposporophyte development from members of that group.

Key Words::

• Acrotylaceae
• Areschougiaceae
• Chemotaxonomy
• Claviclonium ovatum
• Polysaccharide structure
• Spectroscopy
• Systematics

ACKNOWLEDGMENTS

We acknowledge support from the Australian Government to the Cooperative Research Centre for Bioproducts.