title: Ability of multicellular salt glands in Tamarix species to secrete Na+ and K+ selectively.
abstract: The present study aimed to determine the mechanism of cation-selective secretion by multicellular salt glands. Using a hydroponic culture system, the secretion and accumulation of Na(+) and K(+) in Tamarix ramosissima and T. laxa under different salt stresses (NaCl, KCl and NaCl+KCl) were studied. Additionally, the effects of salt gland inhibitors (orthovanadate, Ba(2+), ouabain, tetraethylammonium (TEA) and verapamil) on Na(+) and K(+) secretion and accumulation were examined. Treatment with NaCl (at 0-200 mmol L(-1) levels) significantly increased Na(+) secretion, whereas KCl treatment (at 0-200 mmol L(-1) levels) significantly increased K(+) secretion. The ratio of secretion to accumulation of Na(+) was higher than that of K(+). The changes in Na(+) and K(+) secretion differed after adding different ions into the single-salt solutions. Addition of NaCl to the KCl solution (at 100 mmol L(-1) level, respectively) led to a significant decrease in K(+) secretion rate, whereas addition of KCl to the NaCl solution (at 100 mmol L(-1) level, respectively) had little impact on the Na(+) secretion rate. These results indicated that Na+ secretion in Tamarix was highly selective. In addition, Na(+) secretion was significantly inhibited by orthovanadate, ouabain, TEA and verapamil, and K(+) secretion was significantly inhibited by ouabain, TEA and verapamil. The different impacts of orthovanadate on Na(+) and K(+) secretion might be the primary cause for the different Na(+) and K(+) secretion abilities of multicellular salt glands in Tamarix.
authors.affiliation: Xinjiang Institute of Ecology and Geography, Key Laboratory of Oasis Ecology and Desert, Chinese Academy of Sciences, Urumqi 830011, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Ma
authors.forename: Changyan
authors.initials: C
authors.lastname: Tian
authors.forename: Gu
authors.initials: G
authors.lastname: Feng
authors.forename: Junfeng
authors.initials: J
authors.lastname: Yuan
mesh_terms: D001692:Biological Transport / Q000502:physiology; D009997:Osmotic Pressure; D011188:Potassium / Q000378:metabolism*; D011189:Potassium Chloride / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism; D032363:Tamaricaceae / Q000033:anatomy & histology* / Q000378:metabolism*
chemical_list: D012965:Sodium Chloride; D011189:Potassium Chloride; D012964:Sodium; D011188:Potassium