Accumulation of ions during seed development under controlled saline conditions of two Suaeda salsa populations is related to their adaptation to saline environments

Abstract

Controlled conditions were used to investigate the relationship between ion distribution in developing seeds of two Suaeda salsa populations and seed germination and seedling emergence. Seeds were harvested from S. salsa plants that had been treated with 1 or 400 mM NaCl for 122 (saline inland population) or 135 days (intertidal zone population) in a glasshouse. Germination and seedling emergence were evaluated under salinity. In both populations, more ions were accumulated in the pericarps of plants cultured in 400 mM NaCl than in 1 mM NaCl. Pericarps accumulated much higher ion concentrations in the intertidal zone population than in the saline inland population, while the opposite trend occurred for ion accumulation in the embryos. Seeds of plants from the intertidal zone population germinated more rapidly than those from plants of the saline inland population, regardless of the NaCl concentration during seed germination. However, seedling emergence under high salinity was lower with seeds from the intertidal zone population than with seeds from the saline inland population. In conclusion, S. salsa in the intertidal zone employs superior control of ion compartmentalization in the pericarps to tolerate salinity but requires a minimal level of ions in embryos to ensure seedling establishment in highly saline environments. This indicates that euhalophytes require salts during the mature seed stage to maintain seed viability and to ensure seedling emergence and population establishment.

Relationships between ion and chlorophyll accumulation in seeds and adaptation to saline environments in Suaeda salsa populations

“…The intertidal population is usually submerged completely in seawater during its whole life cycle, and the salt concentrations in the soil are always higher than the inland population (Liu 2006;Song et al 2009b). The present results support the previous suggestions referred by Li et al (2011), i.e. the intertidal population should accumulate a minimal level of ions in embryos to ensure seedling establishment in highly saline environments.…”

“…Means in each column that have different letters are significantly different at P 5 0.05; data are means+SE, n ¼ 4. intertidal population than in the inland population when plants were cultured in 400 mM NaCl. Correspondingly, seedling emergence at 600 mM NaCl was lower with seeds from the intertidal population than with seeds from the inland population (Li et al 2011). They suggested that plants of the intertidal population required a minimal level of ions in embryos to ensure seedling establishment in highly saline environments (Li et al 2011).…”

“…Correspondingly, seedling emergence at 600 mM NaCl was lower with seeds from the intertidal population than with seeds from the inland population (Li et al 2011). They suggested that plants of the intertidal population required a minimal level of ions in embryos to ensure seedling establishment in highly saline environments (Li et al 2011). In the present study, there was no difference in the contents of total ions of embryos in the two populations.…”

“…For example, more Na þ is compartmentalized in the seed coat than in the embryo of the halophytes S. physophora and Haloxylon ammodendron which are common plant species in the Zhunger Basin in China, one of the driest regions in the world, thus may protect embryos from ion toxicity to ensure seed viability during seed development, and may be an adaptive mechanism for halophytes to their saline environments (Song et al 2005). In a greenhouse study, we found that S. salsa in the intertidal zone employed superior control of ion compartmentalization in the pericarps during seed development (Li et al 2011). However, it is unknown how two S. salsa populations differently control ion distribution in different parts of seeds during seed development in field condition.…”

The inward-rectifying K+ channel SsAKT1 is a candidate involved in K+ uptake in the halophyte Suaeda salsa under saline condition

“…salsa), a C 3 plant distributed in saline soil areas of northern China, has been paid much attention due to its economic and ecological value in saline agriculture (Li et al 2011;Song et al 2008;Zhao et al 2002). S. salsa grows optimally in the presence of about 200 mM NaCl (Song and Wang 2014) and accumulates Na + to the concentration of about 400 mM based on the tissue water content in its leaves without injury, indicating that S. salsa is a typical salt-accumulating halophyte (Wang et al 2004(Wang et al , 2007Zhang et al 2013).…”