A conserved primary salt tolerance mechanism mediated by HKT transporters: a mechanism for sodium exclusion and maintenance of high K(+)/Na(+) ratio in leaves during salinity stress.
Increasing soil salinity is a serious threat to agricultural productions worldwide in the 21st century. Several essential Na(+) transporters such as AtNHX1 and AtSOS1 function in Na(+) tolerance under salinity stress in plants. Recently, evidence for a new primary salt tolerance mechanism has been reported, which is mediated by a class of HKT transporters both in dicots such as Arabidopsis and monocot crops such as rice and wheat. Here we present a review on vital physiological functions of HKT transporters including AtHKT1;1 and OsHKT1;5 in preventing shoot Na(+) over-accumulation by mediating Na(+) exclusion from xylem vessels in the presence of a large amount of Na(+) thereby protecting leaves from salinity stress. Findings of the HKT2 transporter sub-family are also updated in this review. Subjects regarding function and regulation of HKT transporters, which need to be elucidated in future research, are discussed.
Hauser
Felix
F
Center for Molecular Genetics, University of California, San Diego, La Jolla, 92093-0116, USA.
Horie
Tomoaki
T
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D054712:Salinity; D055051:Salt-Tolerant Plants / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D052584:Xylem / Q000378:metabolism
D027682:Cation Transport Proteins; C088864:HKT1 protein, plant; D010940:Plant Proteins; D027981:Symporters; D012964:Sodium; D011188:Potassium