Iron (II)-EDTA alleviate salinity injury through regulating ion balance in halophyte seashore paspalum

Salt stress is one of the most important abiotic stresses that limits plant growth and development. In high salinity environments, plants adapt to stress mainly by changing their appearance and cell physiological metabolism. Iron is an important trace element in plant growth and development. It is not only an important factor affecting plant photosynthesis but also an ion to maintain plant homeostasis. To ensure the efficient utilization of iron nutrition, Fe (II) EDTA is usually used in iron supplementation of plants. In this study, the aim was to investigate the effects of excessive iron (Fe (II) EDTA) on physiological responses and expression levels of salt-tolerance-related genes in seashore paspalum under salt stress. The results showed that the salt toxicity could be alleviated by applying appropriate excess Fe (II) EDTA under salt stress. Plant biomass, chlorophyll content, net photosynthetic rate (Pn), photochemical efficiency (Fv/Fm), and root activity were improved by excess Fe (II) EDTA under salt stress. High concentration Fe (II) EDTA significantly reduced Na⁺ content, increased K⁺/ Na⁺, and significantly increased Ca²⁺, Mg²⁺, Mn²⁺, and Fe²⁺ contents in seashore pasplum roots under salt stress. The expression levels of salt-tolerance related genes (<i>PvSOS1</i>, <i>PvCIPK24</i>, <i>PvCBL4</i> (Na⁺/H⁺ transporter), <i>PvHKT1</i> (K⁺ transporter), <i>PvPHA,</i> and <i>PvVHA</i> (proton pump) were significantly increased by excess Fe (II) EDTA under salt stress. Therefore, the results of this study suggested that excess Fe (II) EDTA treatment can effectively enhance salt tolerance of seashore paspalum by maintaining ion balance.