| The biochemical and molecular mechanisms of Ascophyllum nodosum (brown seaweed) extract-mediated freezing tolerance in Arabidopsis thaliana was investigated. Plants treated with A. nodosum extract and its lipophilic components (LPC) accumulated higher concentration of proline and soluble sugars as compared to untreated controls when exposed to sub-zero temperatures. 1H NMR metabolite profile of LPC-treated Arabidopsis revealed an enhanced accumulation of sugars, sugar alcohols and organic acids and also an increased degree of fatty acid unsaturation. A. nodosum extract treatment caused an increase in transcription of the cold response genes, COR15A, RD29A and the transcription factor CBF3. Global transcriptome analysis revealed that LPC treatment altered the expression of 1113 genes, many of which have a functional role in the synthesis of osmoprotectants and in the regulation of membrane lipids. Taken together, the results suggest that A. nodosum extracts enhance freezing tolerance through priming for higher accumulation of osmoprotectants and fatty acid unsaturation. |
