K+ accumulation in the cytoplasm and nucleus of the salt gland cells of Limonium bicolor accompanies increased rates of salt secretion under NaCl treatment using NanoSIMS

• Published in: Plant science (Limerick) Vol. 238; pp. 286 - 296
• Main Authors: Feng, Zhong-Tao, Deng, Yun-Quan, Zhang, Shi-Chao, Liang, Xue, Yuan, Fang, Hao, Jia-Long, Zhang, Jian-Chao, Sun, Shu-Feng, Wang, Bao-Shan
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01.09.2015
• Subjects: Cell Nucleus - drug effects; Cell Nucleus - metabolism; Cytoplasm - drug effects; Cytoplasm - metabolism; Elemental localization; Ions; Limonium bicolor; NanoSIMS; Nanotechnology; NMT; Plant Leaves - drug effects; Plant Leaves - metabolism; Plumbaginaceae - anatomy & histology; Plumbaginaceae - cytology; Plumbaginaceae - metabolism; Plumbaginaceae - ultrastructure; Potassium - metabolism; Salt gland; Sodium - metabolism; Sodium Chloride - pharmacology; Spectrometry, Mass, Secondary Ion - methods; Ultrastructure; NanoSIMS; Salt gland; DAPI; DM; MRP; FS; LSCM; SE; Limonium bicolor; NMT; Ultrastructure; Elemental localization; SEM; SIMS; PPFD; TEM; HPF
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2015.06.021

•There are 16 cells in the salt gland of L. bicolor, including four secretory cells.•NaCl treatment enhanced K+ accumulation in cytoplasm and nucleus of salt gland cells.•Higher signal strength of Na+ was located in the apoplast of salt gland cells.•NaCl treatment markedly increased Na+ secretion rate but decreased K+ secretion rate. Recretohalophytes with specialized salt-secreting structures (salt glands) can secrete excess salts from plant, while discriminating between Na+ and K+. K+/Na+ ratio plays an important role in plant salt tolerance, but the distribution and role of K+ in the salt gland cells is poorly understood. In this article, the in situ subcellular localization of K and Na in the salt gland of the recretohalophyte Limonium bicolor Kuntze is described. Samples were prepared by high-pressure freezing (HPF), freeze substitution (FS) and analyzed using NanoSIMS. The salt gland of L. bicolor consists of sixteen cells. Higher signal strength of Na+ was located in the apoplast of salt gland cells. Compared with control, 200mM NaCl treatment led to higher signal strength of K+ and Na+ in both cytoplasm and nucleus of salt gland cells although K+/Na+ ratio in both cytoplasm and nucleus were slightly reduced by NaCl. Moreover, the rate of Na+ secretion per salt gland of L. bicolor treated with 200mM NaCl was five times that of controls. These results suggest that K+ accumulation both in the cytoplasm and nucleus of salt gland cells under salinity may play an important role in salt secretion, although the exact mechanism is unknown.