Abstract
Salinity stress in Brassica, often only associated with osmotic effects and the toxicity of Na+, was more severe when applied as Na2SO4 than as NaCl, indicating that SO42− ions had toxic effects as well. Application of 10 mM calcium in the form of CaCl2 in the growth medium of plants only slightly ameliorated growth impairment by NaCl and KCl, but almost completely prevented negative effects of Na2SO4 and K2SO4 on plant biomass production. This effect was calcium specific, as MgCl2 ameliorated sulfate toxicity to a much lower extent. This sulfate toxicity coincided with a strong decrease in the plant content of calcium and manganese upon sulfate salinity. Application of CaCl2 largely alleviated this decrease, however, it did not prevent the higher tissue concentration of sulfate. CaCl2 prevented the increase in organic sulfur compounds presumably by reducing of relative gene expression of ATP-sulfurylase (ATPS) and adenosine 5′-phosphosulfate reductase (APR) indicating a possible regulation of sulfate assimilation by calcium. The upregulation of the genes encoding for Group 4 sulfate transporters (Sultr4;1 and 4;2) upon sulfate salinity, was absent in the presence of CaCl2. Therefore, additional calcium may facilitate an increased vacuolar capacity for sulfate accumulation.
Highlights
Salt stress is an increasing problem for cropproduction and much research has been carried out on the phenomena of salt stress and tolerance in plants, progress in increasing crop salt tolerance via breeding remains rather limited
This may cause a loss of potassium from roots, which may be partly prevented by addition of calcium (Shabala, 2000)
The results provide new insights in the mechanisms of sulfate toxicity and in the specificity of calcium in amelioration of stress caused by different salts
Summary
Salt stress is an increasing problem for cropproduction and much research has been carried out on the phenomena of salt stress and tolerance in plants, progress in increasing crop salt tolerance via breeding remains rather limited. Amelioration of salt stress by calcium has, up to now, almost exclusively been related to sodium toxicity, due to the fact that sodium as a cation competes with calcium in cell walls and membranes and disturbs their function as selective barriers (Cramer et al, 1985; Lynch et al, 1987; Rengel, 1992). This may cause a loss of potassium from roots, which may be partly prevented by addition of calcium (Shabala, 2000). The important role of calcium for potassium/sodium homeostasis under salt stress is widely accepted (Epstein, 1998; Volkmar et al, 1998)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
