Brief exposure to low-pH stress causes irreversible damage to the growing root in Arabidopsis thaliana:: pectin-Ca interaction may play an important role in proton rhizotoxicity
Brief exposure to low-pH stress causes irreversible damage to the growing root in Arabidopsis thaliana:: pectin-Ca interaction may play an important role in proton rhizotoxicity
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DOI：
10.1093/jexbot/52.355.361
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发表时间：
2001-02-01
影响因子：
6.9
通讯作者：
Hara, T
中科院分区：
文献类型：
--
作者：
Koyama, H;Toda, T;Hara, T
通过荧光素二乙酸-碘化丙啶染色来检查暴露于含有 100 μM CaCl2 的低 pH（4.5 或 4.7）溶液的拟南芥（Landsberg 株）根部的活力，生长根的伸长区在暴露于低 pH 值后 1-2 小时内失去活力，但非生长根在相同处理下没有表现出损害。通过在 pH 5.6 的生长介质中的再生长来判断，在 pH 4.5 下孵育 1 小时后，生长根的低 pH 损伤是不可逆的。在相同处理中，生长的侧根也失去了活力，而非生长的侧根在处理期间和处理后仍然保持活力。同时施用钙可改善低 pH 值损伤，表明需要钙的过程参与克服质子毒性。在pH 5.0时，生长的根需要25μM的钙来维持伸长，在pH 4.8和pH 4.5时分别需要超过250μM和750μM。二价阳离子可改善低pH损伤，顺序为Ba2+近似于Sr2+大于或等于Ca2+>Mg2+，一价阳离子K+没有显示出改善作用，但贝酸盐对Ca2+显示出强烈的改善作用。这些结果表明，质子毒性的主要目标可能与果胶多糖网络稳定性的干扰有关，其中钙 在植物根系中起关键作用。
The viability of Arabidopsis thaliana (strain Landsberg) roots exposed to a low pH (4.5 or 4.7) solution that contained 100 muM CaCl2 was examined by staining with fluorescein diacetate-propidium iodide, The elongation zone of growing roots lost viability within 1-2 h following exposure to low pH, but non-growing roots showed no damage under the same treatment. Low-pH damage in growing roots was irreversible after 1 h incubation at pH 4.5 as judged by regrowth in growing medium at pH 5.6, Growing lateral roots also lost viability in the same treatment, whereas non-growing lateral roots remained viable during and after the treatment. The low-pH damage was ameliorated by the simultaneous application of calcium, indicating the involvement of a calcium-requiring process in overcoming proton toxicity. At pH 5.0, growing roots required 25 muM of calcium to maintain elongation, and at pH 4.8 and pH 4.5 more than 250 muM and 750 muM, respectively. The low-pH damage was ameliorated by divalent cations in the Order of Ba2+ approximate to Sr2+ greater than or equal to Ca2+ > Mg2+, The monovalent cation K+ showed no ameliorative effect, but berate showed a strong ameliorative effect with Ca2+, These results indicate that the primary target of proton toxicity may be linked to a disturbance of the stability in the pectic polysaccharide network, where calcium plays a key role in plant roots.