The role of salinity in seed maturation of the euhalophyte Suaeda salsa

Controlled conditions were used to investigate how salinity maintains the salt tolerance of seeds and seedlings of the euhalophyte Suaeda salsa. Seeds were harvested from S. salsa plants that had been treated with 1 or 500mM NaCl for 113 days in a glasshouse. The results showed that high salinity (500mM NaCl) increased chlorophyll concentration and oxygen production in embryos of maturing seeds. At 500mM NaCl, the phosphatidylglycerol and sulfoquinovosyldiacylglycerol levels and the digalactosyldiacylglycerol/monogalactosyldiacylglycerol ratio were higher in young seedlings derived from seeds whose source plants were cultured in 500mM rather than in 1mM NaCl. When seeds were incubated with 600mM NaCl, the conductivity and malondialdehyde concentration in the embryos was greater if the source plants had been cultured in 1mM rather than in 500mM NaCl. The opposite pattern was evident for seedling survival and shoot weight. In conclusion, salinity during seed maturation may increase the salt tolerance of seeds and seedlings by increasing the oxygen production in the embryos of the maturing seeds and by changing the lipid composition of membranes in the seedlings.