關鍵詞：鹽脅迫(salt-stress); 大麥(barley); 非損傷離子選擇性微電極技術(MIFE); K+ flux; Na+ flux.
參考文獻：Zhonghua Chen, et al, Plant Physiology, 2007,145, 1714-1725
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ABSTRACT:
Plant salinity tolerance is a polygenic trait with contributions from genetic, developmental, and physiological interactions, in addition to interactions between the plant and its environment. In this study, we show that in salt-tolerant genotypes of barley (Hordeum vulgare), multiple mechanisms are well combined to withstand saline conditions. These mechanisms include: (1) better control of membrane voltage so retaining a more negative membrane potential; (2) intrinsically higher H+ pump activity; (3) better ability of root cells to pump Na+ from the cytosol to the external medium; and (4) higher sensitivity to supplemental Ca2+. At the same time, no significant difference was found between contrasting cultivars in their unidirectional 22Na+ influx or in the density and voltage dependence of depolarization-activated outward-rectifying K+ channels. Overall, our results are consistent with the idea of the cytosolic K+-to-Na+ ratio being a key determinant of plant salinity tolerance, and suggest multiple pathways of controlling that important feature in salt-tolerant plants.
植物的耐鹽性是一個由遺傳、發育、生理，以及植物與環境之間的相互作用引起的多基因性狀。胞內的Na+/K+平衡是植物耐鹽性的關鍵因素，在鹽環境中植物會阻止胞內Na+的過度積累，維持胞內的K+濃度，保持一個合適的胞內Na+/K+比率來抵御鹽脅迫，然而，這一過程是怎么實現的我們知之甚少。 2007年，澳大利亞的科學家采用“非損傷微測”等技術研究了鹽脅迫下大麥的K+流和Na+流，揭開了Na+/K+平衡實現的過程。耐鹽基因型大麥實現抗鹽這一過程是多種機制綜合作用的結果，這些機制包括：（1）通過控制膜電壓來保持更高的負電勢；（2）提高H+泵的活性；（3）提高細胞的排Na+能力；（4）增加對Ca2+的敏感性。同時，對照品種的單向22Na+流入或者去極化激活后的外流K+通道的密度和電壓依賴性不存在顯著差異。研究結果和K+/Na+是植物耐鹽性的決定因素相一致，說明植物的耐鹽是由多種途徑控制。這個研究結果為品種篩選提供了一種有效的方法。 將非損傷微測技術應用于離子轉運機制的研究中，檢測離子的動態平衡和其他信息，已經被科研人員廣泛接受并實際應用，取得了突破性的進展。 |
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