Calcium signalling in Arabidopsis thaliana responding to drought and salinity
Calcium signalling in Arabidopsis thaliana responding to drought and salinity
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DOI：
10.1046/j.1365-313x.1997.12051067.x
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发表时间：
1997-11-01
期刊：
影响因子：
7.2
通讯作者：
Knight, MR
中科院分区：
文献类型：
--
作者：
Knight, H;Trewavas, AJ;Knight, MR
在完整的拟南芥幼苗体内检测了甘露醇（干旱）和盐处理后胞质游离钙浓度（[Ca²⁺](cyt)）的变化。观察到[Ca²⁺](cyt)瞬时升高至约1.5 μM，并且这种升高被钙通道阻滞剂镧预处理显著抑制，被钙螯合剂EGTA抑制的程度较小。三个基因的表达，即编码脯氨酸生物合成途径中第一个酶Δ(1)-吡咯啉-5-羧酸合成酶（P5CS）的p5cs基因，以及编码功能未知蛋白质的rab18和lti78基因，都被甘露醇和盐处理诱导。甘露醇对这三个基因的诱导被镧预处理抑制。盐诱导的p5cs基因表达，但rab18和lti78基因表达不受镧抑制。甘露醇对p5cs基因的诱导也被钙通道阻滞剂钆和维拉帕米以及钙螯合剂EGTA抑制，进一步表明钙信号传导参与了这种反应。在相对高浓度和低浓度下，甘露醇诱导的p5cs基因表达水平都比等渗浓度的盐更高。然而，对甘露醇和等渗浓度盐的钙瞬变幅度和持续时间相似，这表明在拟南芥中区分干旱和盐度信号涉及除钙以外的一个因素。为了评估液泡作为细胞内钙库在拟南芥对甘露醇反应中的作用，在液泡膜附近的微区测量了[Ca²⁺](cyt)。所得结果与液泡中大量钙释放有助于甘露醇诱导的整体[Ca²⁺](cyt)反应相一致。使用肌醇信号传导抑制剂获得的数据表明，这种释放是通过依赖IP3的钙通道发生的。
Changes in cytosolic free calcium concentration ([Ca2+](cyt)) in response to mannitol (drought) and salt treatments were detected in vivo in intact whole Arabidopsis seedlings. Transient elevations of [Ca2+](cyt) to around 1.5 mu M were observed, and these were substantially inhibited by pretreatment with the calcium-channel blocker lanthanum and to a lesser extent, the calcium-chelator EGTA. The expression of three genes, p5cs, which encodes Delta(1)-pyrroline-5-carboxylate synthetase (P5CS), the first enzyme of the proline biosynthesis pathway, rab18 and lti78 which both encode proteins of unknown function, was induced by mannitol and salt treatments. The induction of all three genes by mannitol was inhibited by pretreatment with lanthanum. Salt-induced p5cs, but not rab18 and lti78, expression was also inhibited by lanthanum. Induction of p5cs by mannitol was also inhibited by the calcium channel-blockers gadolinium and verapamil and the calcium chelator EGTA, further suggesting the involvement of calcium signalling in this response. Mannitol induced greater levels of p5cs gene expression than an isoosmolar concentration of salt, at both relatively high and low concentrations. However, calcium transients were of a similar magnitude and duration in response to both mannitol and isoosmolar concentrations of salt, suggesting that a factor other than calcium is involved in the discrimination between drought and salinity signals in Arabidopsis. In order to gauge the involvement of the vacuole as an intracellular calcium store in the response of Arabidopsis to mannitol, [Ca2+](cyt) was measured at the microdomain adjacent to the vacuolar membrane. The results obtained were consistent with a significant calcium release from the vacuole contributing to the overall mannitol-induced [Ca2+](cyt) response. Data obtained by using inhibitors of inositol signalling suggested that this release was occurring through IP3-dependent calcium channels.