How do vacuolar NHX exchangers function in plant salt tolerance?
Potassium (K(+)) is a major osmoticum of plant cells, and the vacuolar accumulation of this element is a especially crucial feature for plants under high-salt conditions. Emerging evidence indicates that cation/proton transporters of the NHX family are instrumental in the H(+)-linked K(+) transport that mediate active K(+) uptake at the tonoplast for the unequal partitioning of K(+) between vacuole and cytosol. However, and in spite of tenuous supporting evidence, NHX proteins are widely regarded as key players in the sequestration of sodium (Na(+)) into vacuoles to avert ion toxicity in the cytosol of plants under salinity stress. Here, we propose an updated model positing that NHX proteins fulfill a protective function to minimize salt-related stress mainly through the vacuolar compartmentalization of K(+) and, in some cases, of Na(+) as well thereby preventing toxic Na(+)-K(+) ratios in the cytosol while accruing solutes for osmotic balance.
Jiang
Xingyu
X
Instituto de Recursos Naturales y Agrobiologia de Sevilla, Consejo Superior de Investigaciones Cientificas, Reina Mercedes, Sevilla, Spain.
Leidi
Eduardo O
EO
Pardo
Jose M
JM
D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D055051:Salt-Tolerant Plants / Q000235:genetics / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism*
D027682:Cation Transport Proteins; D010940:Plant Proteins; D017923:Sodium-Hydrogen Exchangers; D011188:Potassium