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Salt tolerance of B eta macrocarpa is associated with efficient osmotic adjustment and increased apoplastic water content
Author(s) -
Hamouda I.,
Badri M.,
Mejri M.,
Cruz C.,
Siddique K. H. M.,
Hessini K.
Publication year - 2016
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1111/plb.12419
Subject(s) - apoplast , salinity , halophyte , biology , osmotic pressure , osmoprotectant , osmoregulation , proline , photosynthesis , botany , osmotic shock , stomatal conductance , salt (chemistry) , horticulture , biochemistry , chemistry , cell wall , ecology , amino acid , gene
The chenopod Beta macrocarpa Guss (wild Swiss chard) is known for its salt tolerance, but the mechanisms involved are still debated. In order to elucidate the processes involved, we grew wild Swiss chard exposed to three salinity levels (0, 100 and 200 m m NaCl) for 45 days, and determined several physiological parameters at the end of this time. All plants survived despite reductions in growth, photosynthesis and stomatal conductance in plants exposed to salinity (100 and 200 m m NaCl). As expected, the negative effects of salinity were more pronounced at 200 m m than at 100 m m NaCl: (i) leaf apoplastic water content was maintained or increased despite a significant reduction in leaf water potential, revealing the halophytic character of B. macrocarpa ; (ii) osmotic adjustment occurred, which presumably enhanced the driving force for water extraction from soil, and avoided toxic build up of Na + and Cl – in the mesophyll apoplast of leaves. Osmotic adjustment mainly occurred through accumulation of inorganic ions and to a lesser extent soluble sugars; proline was not implicated in osmotic adjustment. Overall, two important mechanisms of salt tolerance in B. macrocarpa were identified: osmotic and apoplastic water adjustment.