Jones D L, Gilroy S, Larsen P B, Howell S H, Kochian L V
School of Agricultural and Forest Sciences, University of Wales, Bangor, Gwynedd, UK.
Planta. 1998 Oct;206(3):378-87. doi: 10.1007/s004250050413.
Aluminum inhibition of root growth is a major world agricultural problem where the cause of toxicity has been linked to changes in cellular calcium homeostasis. Therefore, the effect of aluminum ions (Al) on changes in cytoplasmic free calcium concentration ([Ca2+]c) was followed in root hairs of wild-type, Al-sensitive and Al-resistant mutants of Arabidopsis thaliana (L.) Heynh. Generally, Al exposure resulted in prolonged elevations in tip-localized [Ca2+]c in both wild-type and Al-sensitive root hairs. However, these Al-induced increases in [Ca2+]c were not tightly correlated with growth inhibition, occurring up to 15 min after Al had induced growth to stop. Also, in 32% of root hairs examined growth stopped without a detectable change in [Ca2+]c. In contrast, Al-resistant mutants showed little growth inhibition in response to AlCl3 exposure and in no case was a change in [Ca2+]c observed. Of the other externally applied stresses tested (oxidative and mechanical stress), both were found to inhibit root hair growth, but only oxidative stress (H2O2, 10 microM) caused a prolonged rise in [Ca2+]c similar to that induced by Al. Again this increase occurred after growth had been inhibited. The lack of a tight correlation between Al exposure, growth inhibition and altered [Ca2+]c dynamics suggests that although exposure of root hairs to toxic levels of Al causes an alteration in cellular Ca2+ homeostasis, this may not be a required event for Al toxicity. The elevation in [Ca2+]c induced by Al also strongly suggests that the phytotoxic action of Al in root hairs is not through blockage of Ca2(+)-permeable channels required for Ca2+ influx into the cytoplasm.
铝对根系生长的抑制是一个全球性的重大农业问题，其毒性成因与细胞钙稳态的变化有关。因此，我们研究了铝离子（Al）对拟南芥（L.）海因茨野生型、铝敏感型和铝抗性突变体根毛细胞质游离钙浓度（[Ca2+]c）变化的影响。一般来说，铝处理会导致野生型和铝敏感型根毛尖端局部[Ca2+]c持续升高。然而，这些铝诱导的[Ca2+]c升高与生长抑制并没有紧密的相关性，在铝诱导生长停止后15分钟内仍会出现。此外，在32%检测的根毛中，生长停止时[Ca2+]c没有可检测到的变化。相比之下，铝抗性突变体在暴露于AlCl3时几乎没有生长抑制，并且在任何情况下都未观察到[Ca2+]c的变化。在测试的其他外部施加的胁迫（氧化和机械胁迫）中，两者都被发现会抑制根毛生长，但只有氧化胁迫（H2O2，10 microM）会导致[Ca2+]c持续升高，类似于铝诱导的升高。同样，这种升高也是在生长受到抑制之后出现的。铝暴露、生长抑制和[Ca2+]c动态变化之间缺乏紧密相关性表明，尽管根毛暴露于有毒水平的铝会导致细胞钙稳态改变，但这可能不是铝毒性所必需的事件。铝诱导的[Ca2+]c升高也强烈表明，铝在根毛中的植物毒性作用不是通过阻断Ca2+流入细胞质所需的Ca2(+)-渗透通道。
