Abstract
Halophytes are adapted to saline environments and demonstrate optimal reproductive growth under high salinity. To gain insight into the salt tolerance mechanism and effects of salinity in the halophyte Suaeda salsa, the number of flowers and seeds, seed size, anther development, ion content, and flower transcript profiles, as well as the relative expression levels of genes involved in ion transport, were analyzed in S. salsa plants treated with 0 or 200 mM NaCl. The seed size, flower number, seed number per leaf axil, and anther fertility were all significantly increased by 200 mM NaCl treatment. The Na+ and Cl− contents in the leaves, stems, and pollen of NaCl-treated plants were all markedly higher, and the K+ content in the leaves and stems was significantly lower, than those in untreated control plants. By contrast, the K+ content in pollen grains did not decrease, but rather increased, upon NaCl treatment. Genes related to Na+, K+ and, Cl− transport, such as SOS1, KEA, AKT1, NHX1, and CHX, showed increased expression in the flowers of NaCl-treated plants. These results suggest that ionic homeostasis in reproductive organs, especially in pollen grains under salt-treated conditions, involves increased expression of ion transport-related genes.
Highlights
Salinity is an increasing problem worldwide, and can severely reduce crop growth and yield, in irrigated land (Greenway and Munns, 1980; Munns, 2002; Rengasamy, 2006)
We found that the 200 mM NaCl treatment did not inhibit S. salsa growth; on the contrary, this treatment significantly increased the fresh weight (FW), dry weight, plant height, and primary branch number of S. salsa, by 67.6, 40.7, 13.3, and 12.3%, respectively, compared with the control plants (Supplementary Figure S1)
Na+ enters S. salsa cells mainly through the high-affinity K+ transporter HKT1 and nonselective cation channels NSCC on the plasma membrane, and excess Na+ is compartmentalized into the vacuole through the intracellular Na+/H+ antiporter NHX1 on the tonoplast, thereby maintaining a relatively higher Na+ content in the leaves, stems, and floral organs than in control plants not exposed to high levels of NaCl
Summary
Salinity is an increasing problem worldwide, and can severely reduce crop growth and yield, in irrigated land (Greenway and Munns, 1980; Munns, 2002; Rengasamy, 2006). In the vegetative growth stage, euhalophyte survival mainly depends on the exclusion of Na+ and Cl− and/or sequestration of these ions into vacuoles, which maintains ionic homeostasis and avoids toxicity in young, growing leaves (Wang et al, 2004; Han et al, 2005; Qiu et al, 2007; Munns and Tester, 2008; Yang et al, 2010). It is unclear whether the mechanism of salt tolerance in reproductive growth processes of euhalophytes is same as that in vegetative growth processes. Identifying the molecular mechanism underlying salt tolerance during the reproductive development of halophytes may present a strategy to generate crops that can withstand saline soil
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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 call
