Mukherjee Soumya, Bhatla Satish Chander
Laboratory of Plant Physiology and Biochemistry, Department of Botany, University of Delhi, Delhi, 110007, India.
Physiol Plant. 2014 Apr;150(4):540-9. doi: 10.1111/ppl.12101. Epub 2013 Oct 12.
Seedlings exposed to salt stress are expected to show modulation of intracellular accumulation of sodium ions through a variety of mechanisms. Using a new methodology, this work demonstrates ouabain (OU)-sensitive ATPase activity in the roots of sunflower seedlings subjected to salt stress (120 mM NaCl). 9-Anthroylouabain (a derivative of ouabain known to inhibit Na(+), K(+) -ATPase activity in animal systems, EC 3.6.3.9) has been used as a probe to analyze OU-sensitive ATPase activity in sunflower (Helianthus annuus) seedling roots by spectrofluorometric estimation and localization of its spatial distribution using confocal laser scanning microscopy. Salt stress for 48 h leads to a significant induction of OU-sensitive ATPase activity in the meristematic region of the seedling roots. Calcium ions (10 mM) significantly inhibit enzyme activity and a parallel accumulation of sodium ions in the cytosol of the columella cells, epidermis and in the cells of the meristematic region of the roots is evident. As a rapid response to NaCl stress, the activity of OU-sensitive ATPase gets localized in the nuclear membrane of root protoplasts and it gets inhibited after treatment with calcium ions. Nuclear membrane localization of the OU-sensitive ATPase activity highlights a possible mechanism to efflux sodium ions from the nucleus. Thus, a correlation between OU-sensitive ATPase activity, its modulation by calcium ions and accumulation of sodium ions in various regions of the seedling roots, has been demonstrated using a novel approach in a plant system.
暴露于盐胁迫下的幼苗有望通过多种机制调节细胞内钠离子的积累。利用一种新方法，这项研究证明了在遭受盐胁迫（120 mM NaCl）的向日葵幼苗根部存在哇巴因（OU）敏感的ATP酶活性。9-蒽基哇巴因（一种已知能抑制动物系统中Na(+)、K(+) -ATP酶活性的哇巴因衍生物，EC 3.6.3.9）已被用作探针，通过荧光光谱法估计并利用共聚焦激光扫描显微镜定位其空间分布，来分析向日葵（Helianthus annuus）幼苗根部的OU敏感ATP酶活性。48小时的盐胁迫导致幼苗根部分生组织区域中OU敏感ATP酶活性显著诱导。钙离子（10 mM）显著抑制酶活性，并且在根冠细胞、表皮以及根部分生组织区域的细胞胞质溶胶中钠离子平行积累明显。作为对NaCl胁迫的快速反应，OU敏感ATP酶的活性定位于根原生质体的核膜上，并且在用钙离子处理后受到抑制。OU敏感ATP酶活性的核膜定位突出了一种从细胞核中排出钠离子的可能机制。因此，利用一种新颖的方法在植物系统中证明了OU敏感ATP酶活性、其受钙离子调节以及幼苗根不同区域中钠离子积累之间的相关性。
