**3.3 Sos (salt overly sensitive) signaling**

Salinity is the most important abiotic stress that diminishes rice crop productivity. Plants suffer from severe osmotic pressure and a scarcity of water as a result of salinity, which causes ions to accumulate in their tissues. Different rice varieties have different levels of tolerance [63]. IR29, for example, is a salt-sensitive species that accumulates 5–10 times more Na1 in the leaves than Pokkali or BK [64] . Salt tolerance in rice is achieved by limiting Na1 translocation. The gene SKC1/ HKT8 is responsible for salt tolerance and a strong K1/Na1 balance in the shoots, as well as decoding a HKT family Na1 selective transporter that regulates Na1 transport over vast distances [65]. HKT1 is a similar gene that is ubiquitously expressed in the roots and leaves and seems to be involved in the long-distance trafficking of Na1. The Na1/H1 counter transporter salt overly sensitive (SOS)1 can facilitate the outflow of Na1 across the plasma membrane [66]. Plants lacking SOS1 become particularly salt sensitive and their transfer of Na1 over long distances is hampered. The root tip epidermis and xylem parenchyma cells are the primary sites of SOS1 expression. At the root-soil interface, it extrudes too much Na1 from the root epidermal cells. SOS1 seems engaged in the Na1 translocation in the roots and shoots. It's also responsible for providing ions from the xylem to the shoots in a manageable way. The SOS2/ SOS3 kinase complex utilizes SOS1 as a substrate. Plants lacking SOS2 or SOS3 have the same salt sensitivity phenotype as SOS1 plants [64]. Ion homeostasis could be maintained as a result of this.
