Limiting cytosolic Na+ confers salt tolerance to rice cells in culture:: a two-photon microscopy study of SBFI-loaded cells
Limiting cytosolic Na+ confers salt tolerance to rice cells in culture:: a two-photon microscopy study of SBFI-loaded cells
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DOI：
10.1111/j.1399-3054.2006.00854.x
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发表时间：
2007-03-01
影响因子：
6.4
通讯作者：
Mathew, M. K.
中科院分区：
文献类型：
--
作者：
Anil, Veena S.;Krishnamurthy, H.;Mathew, M. K.
水稻是亚洲的主食，对土壤盐分非常敏感。然而，种内存在变异，沿海品种Pokkah甚至耐受咸水。这项研究探索了水稻耐盐性的细胞机制。人们普遍认为，限制细胞内的Na+可以改善植物在盐分胁迫下的存活。然而，要了解相对耐性品种中Na+水平的控制机制，需要非侵入性地实时监测细胞质中的Na+，这在技术上是具有挑战性的。我们已经使用双光子激发来使用钠结合的苯并呋喃间苯二甲酸酯对培养细胞中的胞浆Na+进行比率估计。Pokkali细胞在高盐度下维持低Na+(约25 mm)，存活率在85%以上，而Jaya细胞即使在中等盐胁迫下也不能维持低Na+，细胞存活率下降。在这里，我们发现Pokkali质膜对Na+的通透性明显低于Jaya，其程度与已报道的盐生植物的通透性相当。Pokkali利用钙离子调节的运输系统有效地将Na+隔离在细胞内的隔间中(S)。综上所述，这些细胞机制使Pokkali能够在250 mM的氯化钠胁迫下保持较低的细胞质Na+。这些结果表明，不同水稻品种间存活率的差异主要是由于膜运输机制的差异，因此对作物改良具有重要意义。
Rice (Oryza sativa L.), a staple food in Asia, is very sensitive to soil salinity. However, intraspecific variations exist, with the coastal cultivar Pokkah tolerating even brackish water. This study explores cellular mechanisms that contribute to salt tolerance in rice. It is widely accepted that limiting cytosolic Na+ should improve the survival of plants subjected to saline stress. However, an understanding of the mechanisms by which Na+ levels are controlled in relatively tolerant cultivars requires monitoring cytosolic Na+ non-invasively and in real time, which is technically challenging. We have used two-photon excitation for the ratiometric estimation of cytosolic Na+ in cultured cells using sodium-binding benzofuran isophthalate. Pokkali cells maintained low cytosolic Na+ (approximately 25 mM), and a viability of over 85% under high salinity, while Jaya cells were unable to maintain low cytosolic Na+ and suffered decreased viability even at moderate saline stress. Here we show that the permeability of the Pokkali plasma membrane to Na+ is significantly lower than that of Jaya, to the extent that it is comparable with permeabilities reported for halophytes. Pokkali effectively sequesters Na+ in intracellular compartments utilizing a Ca2+-regulated transport system(s). Together these cellular mechanisms allow Pokkali to maintain low cytosolic Na+ up to a stress of 250 mM NaCl. The findings demonstrate that differences in survival between these contrasting varieties of rice are mainly because of differences in membrane transport mechanisms and thus have significance in crop improvement.