抗凋亡基因（CED-9）提高植株对盐胁迫和氧化应激的耐...
抗凋亡基因（CED-9）提高植株对盐胁迫和氧化应激的耐受性
凋亡(Apoptosis)是细胞程序性死亡的一种，在调节植物对环境的适应性中起到重要作用。近期有研究表明动物的抗凋亡基因(CED-9)在植物中表达，能够显著提高植物对各种生物和非生物胁迫的耐受性，但隐藏在该现象下的最基本的细胞机制尚未被考察。
烟草（Nicotiana benthamiana）瞬时表达了CED-9抗凋亡基因后，对盐胁迫及氧化应激时植株的特定离子流“指纹”进行了研究。使用非损伤微测技术(MIFE)对离子流进行检测，可以看到CED-9基因通过改变跨膜K+和H+离子流的模式来提高植株对盐胁迫和氧化应激的耐受性。
本文首次对植物的“离子流指纹”和细胞程序性死亡机制的关系进行研究，发现CED-9基因可以控制叶肉细胞质膜上的两种K+通道：KOR和NSCC，从而阻止NaCl引起的盐胁迫叶片的K+外流；同时，CED-9基因表达能显著降低氧化应激引起的K+外流，维持胞内离子平衡，以减少氧化应激带来的短期和长期损害。
关键词：离子流(Ion flux), 膜转运(Membrane transport), 凋亡(Apoptosis), 盐胁迫(Salinity), 氧化应激(Oxidative stress)
参考文献：Sergey Shabala, et al. Planta, 2007, 227:189 -197
全文下载：http://www.xuyue.net/xylt/viewthread.php?tid=538&extra=page%3D1
Abstract
Apoptosis, one form of programmed
cell death (PCD), plays an important role in mediating plant adaptive
responses to the environment. Recent studies suggest that expression of
animal anti-apoptotic genes in transgenic plants may signiWcantly
improve a plant’s ability to tolerate a variety of biotic and abiotic
stresses. The underlying cellular mechanisms of this process remain
unexplored. In this study, we investigated speciWc ion Xux “signatures”
in Nicotiana benthamiana plants transiently expressing CED-9
anti-apoptotic gene and undergoing salt- and oxidative stresses. Using a
range of electrophysiological techniques, we show that expression of
CED-9 increased plant salt and oxidative stress tolerance by altering K+ and H+ Xux patterns across the plasma membrane. Our data shows that PVX/CED-9 plants are capable of preventing stress-induced K+ eZux from mesophyll cells, so maintaining intracellular K+ homeostasis. We attribute these eVects to the ability of CED-9 to control at least two types of K+-permeable
channels; outward-rectifying depolarization-activating K+ channels
(KOR) and non-selective cation channels (NSCC). A possible scenario
linking CED-9 expression and ionic relations in plant cell is suggested.
To the best of our knowledge, this study is the Wrst to link “ion Xux
signatures” and mechanisms involved in regulation of PCD in plants.
