A transplantation study in the high-altitude ecosystem of Ladakh suggests site-specific microenvironment is key for physiological adaptation than altitude

Abstract

Transplantation experiments conducted in high altitude ecosystems are rising as key strategy to examine the response of individual plant transplanted across distinct elevations. However, plant physiological and biochemical performance in response to changes in abiotic factors across different species and mountain ranges is still lacking. So in the present study, we have made an attempt to link the physiological performance with that of altitudinal gradient in Ladakh by transplanting Lepidium latifolium at four different altitudinal sites. The plant was found to maintain photosynthesis even at high altitudes by modulating photochemical efficiency of photosystem II. Various physiological processes including performance index (PI_ABS), increase in energy fluxes, closing of the reaction centres and decrease in chlorophyll content play a crucial role in the adaptation of this plant. The efficient and dynamic non-photochemical quenching (NPQ) involving carotenoids particularly zeaxanthin mediated dissipation of excess light energy at high altitudinal sites of Ladakh led the plant to withstand with extremely strong light radiation. As a photoprotective mechanism, decreases in chlorophyll content and increase in carotenoids could lead to a reduction in the absorption of high light energy and avoid photo damage to the chloroplasts. Higher content of redox metabolites such as GSH, ASC, GSH/GSSG ratio and ASC/DHA ratio in plants transplanted at high altitudinal sites further suggests the resilience ability of Lepidium latifolium against harsh environmental stresses. Furthermore, increase in glucosinolate content in plants transplanted at high altitudes suggests the involvement of GLS in the establishment of Lepidium latifolium in Ladakh. Overall, no specific altitudinal trend was observed in the present study indicating the adaptation strategy of Lepidium latifolium to different altitudinal sites can be attributed to the combined effects of multiple environmental factors/microenvironment.