Metabolic insights into high-altitude adaptation of Himalayan ‘Horsetails’ [Equisetum diffusum D. Don] with special reference to the fatty acid dynamicity

• Published in: South African journal of botany 2024-08, Vol.171, p.267-276
• Main Authors: Paine, Anup Kumar, Mitra, Souvik, Bera, Ritwika, Paul, Ishita, Sarkar, Mousumi Poddar
• Format: Article
• Language: English
• Subjects: Adaptation; Equisetum diffusum; Glycolipids; High-altitude; Polyunsaturated fatty acids
• ISSN: 0254-6299; 1727-9321
• DOI: 10.1016/j.sajb.2024.06.009

•Equisetum diffusum modulates fatty acid metabolism to adapt at high altitudes.•PUFA content and unsaturation index of glycolipids enhance with increase in altitude.•Arachidonic acid contributes significantly to the change in PUFA content.•Antioxidant enzyme activity enhances at higher altitudes in response to combined stress.•Accumulation of osmolytes and secondary metabolites augments stress responsive effects. Equisetum diffusum D. Don, a perennial herb of Equisetaceae, is considered as native to the Himalayan mountain range. This plant has prolific distribution along different altitudes of Eastern Himalayan region. Generally, mountain flora, like E. diffusum, experience a combination of contrasting abiotic stresses and may represent a unique natural model for investigating physiological resilience to address climate change. So, the present study has been framed to compare the metabolic responses in E. diffusum growing at different elevation belts with an aim to understand the underlying basis for their high-altitude adjustment ability. The biochemical profiles of this plant, collected from three different altitudinal transects of Darjeeling hills, were compared. The fatty acid profiles of neutral lipids, membrane phospholipids and glycolipids demonstrated palmitic acid and oleic acid as the predominant fatty acids. The major outcome was the substantial increase of polyunsaturated fatty acids (PUFAs) and unsaturation index in glycolipids of the samples collected from higher altitudes. Major proportion of changes in PUFA content was contributed by arachidonic acid. Therefore, the plants homeostatically control the membrane fluidity by enhancing the unsaturation of glycolipid fatty acids. Moreover, significantly higher antioxidant enzyme activities in higher altitude samples reflect the involvement of these enzymes in coping with the oxidative stress condition and membrane damage. The stress responsive effects may be further augmented by enhanced content of secondary metabolites. Therefore, a combination of biochemical responses along with the changes in membrane plasticity can be predicted as the metabolic adjustment strategies for high-altitude adaptation of E. diffusum.