How do vacuolar NHX exchangers function in plant salt tolerance?

• Published in: Plant signaling & behavior 2010-07, Vol.5 (7), p.792-795
• Main Authors: Jiang, Xingyu, Leidi, Eduardo O., Pardo, Jose M.
• Format: Article
• Language: English
• Subjects: Binding; Biology; Bioscience; Calcium; Cancer; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; Cell; Cycle; Gene Expression Regulation, Plant; Landes; Mini-Reviews; Organogenesis; Plant Proteins - genetics; Plant Proteins - metabolism; Potassium - metabolism; Proteins; Salt-Tolerant Plants - genetics; Salt-Tolerant Plants - metabolism; Sodium-Hydrogen Exchangers - genetics; Sodium-Hydrogen Exchangers - metabolism; Vacuoles - metabolism
• ISSN: 1559-2316; 1559-2324; 1559-2324
• DOI: 10.4161/psb.5.7.11767

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.