Chemotaxonomic and evolutionary perspectives of Bryophyta based on multivariate analysis of fatty acid fingerprints of Eastern Himalayan mosses.

Bryophyta comprises one of the earliest lineages of land plants that had implemented remarkable innovations to their lipid metabolic systems for successful adaptation to terrestrial habitat. This study presents a comprehensive investigation of fatty acid profiles of mosses from Eastern Himalayas with an aim to trace their chemotaxonomic and evolutionary implications. Fatty acid compositions of 40 random mosses belonging to major families of Bryophyta were explored by gas chromatographic analysis. A diverse array of saturated, monounsaturated and polyunsaturated fatty acids including rare acetylenic fatty acids were detected. Hexadecanoic acid (C16:0), 9,12 (Z,Z)-octadecadienoic acid (C18:2n6) and 9,12,15 (Z,Z,Z)-octadecatrienoic acid (C18:3n3) were the predominant fatty acids in all the mosses. However, quantitative variation of C20 polyunsaturated fatty acids (PUFAs), specifically 5,8,11,14 (Z,Z,Z,Z)-eicosatetraenoic acid (C20:4n6), among the investigated mosses was the most prominent outcome. The diplolepidous members of Bryidae, especially the mosses of Hypnales, Bryales and Bartramiales contained higher amount of C20 PUFAs compared with the haplolepidous orders. Principal component analyses based on individual fatty acids and other related parameters validated C20:4n6 content and the ratio of C20:4n6/C18:2n6 as the apparent chemotaxonomic discriminants. The prevalent notion of considering 9,12,15-octadecatrien-6-ynoic acid (C18:4a) as the chemomarker of Dicranaceae has also been challenged, since the compound was detected not only in different families of Dicranales, but also in a Pottiales member, Leptodontium viticulosoides. Therefore, an ensemble of fatty acids instead of a single one can be considered as the chemical signature for taxonomic interpretation which may also be vital from an evolutionary standpoint.

"Dicranin" in the Membrane Phospholipids of a Dicranaceae and Pottiaceae Moss Member of the Eastern Himalayan Biodiversity Hotspot.

The phospholipids of two moss samples Oreoweisia laxifolia (Hookf.) Kindb. (family-Dicranaceae Schimp.) and Leptodontium viticulosoides (P. Beauv.) Wijk & Margad (family-Pottiaceae Schimp.) of the Eastern Himalayan Biodiversity Hotspot were investigated to find out any peculiarity in their fatty acid profiles. Detailed analysis of phospholipid classes and the respective fatty acids was performed using high-performance thin-layer chromatography and gas chromatography-mass spectrometry. An array of different saturated and unsaturated fatty acids were detected in both the samples. Although it has been proposed previously that acetylenic fatty acids are associated only with triacylglycerol of storage lipids, the most striking observation of the present investigation is the abundance of an acetylenic fatty acid, octadeca-6-yn-9,12,15-trienoic acid (18:4a), or Dicranin, in the phospholipids of both the mosses. The position of the triple bond in the hydrocarbon chain of the fatty acids was confirmed by dimethyloxazoline derivatization of fatty acids and their characteristic mass fragmentation pattern. The occurrence of Dicranin in phospholipids and in the Pottiaceae family is reported for the first time, with substantial explanations of the observed results. This may raise the issue of rethinking "Dicranin" as a chemotaxonomic marker of Dicranaceae.