Changes in the composition and structure of cell wall polysaccharides from Artemisia annua in response to salt stress

Artemisia annua is cultivated mainly for isolation of artemisinin, a potent antimalarial compound. Moderate salt stress has been proved to increase the artemisinin synthesis by the plant. The aim of this study was to evaluate the influence of salt stress on physiological parameters and cell wall polysaccharides of A. annua. Plants subjected to salt stress displayed reduction in the biomass and length and showed high damage of cellular membranes. Cell wall polysaccharides extracted from aerial parts with hot water, EDTA and NaOH also exhibited modifications in the yield and monosaccharide composition. The main changes were found in the pectic polysaccharides: increase of homogalacturonan domain, increase of neutral side chains and increase in the methyl esterification. ¹H NMR analyses of pectins indicated that for A. annua, arabinans have an important role in coping with salt stress. Hemicellulose domain was also modified under salt stress, with increased xylose contents. The results indicated adaptations in the cell wall of A. annua under salt stress.