Increased salinity stress tolerance of Nicotiana tabacum L. in vitro plants with the addition of xyloglucan oligosaccharides to the culture medium

Xyloglucan oligosaccharides (XGOs), derived from the hydrolysis of plant cell wall xyloglucan, are a novel class of biostimulants that exert positive effects on plant growth and morphology and can enhance plant stress tolerance. The aim of this study was to determine the influence of the application of exogenous Tamarindus indica L. cell wall-derived XGOs on Nicotiana tabacum L. tolerance to salt stress by evaluating morphology, physiological, and metabolic changes. N. tabacum plants were grown in agar-gelled media for 2 mo under salt stress with 100 mM of sodium chloride (NaCl) ± 0.1 μM XGOs. The germination percentage (GP), number of leaves (NL), foliar area (FA), primary root length (PRL), and density of lateral roots (DLR) were measured. In addition, unaffected 21-d-old N. tabacum plants were treated with a salt shock (100 mM NaCl) ± 0.1 μM XGOs. Proline, total chlorophyll, and total carbonyl levels, in addition to lipid peroxidation degree and activities of four enzymes related to oxidative stress, were quantified. The results indicated that XGOs significantly improved N. tabacum plants development after exposure to salt stress. XGOs caused a significant increase in NL and PRL, promoted lateral root formation, and produced an increase in proline and total chlorophyll contents, while reducing protein oxidation and lipid peroxidation. Although the XGOs modulated the activity of the enzymes analyzed, they were not statistically different from the salt control. It was concluded that XGOs may act as metabolic inducers that trigger the physiological responses that counteract the negative effects of oxidative stress under saline conditions.