Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, E-41013, Sevilla, Spain.
Departamento de Biología Animal, Biología Vegetal y Ecología, Facultad de Ciencias Experimentales, Campus de Las Lagunillas s/n, Universidad de Jaén UJA, 23071, Jaén, Spain.
Plant Physiol Biochem. 2023 Sep;202:107965. doi: 10.1016/j.plaphy.2023.107965. Epub 2023 Aug 12.
Boron (B) toxicity causes impairments in several plant metabolic and physiological processes. Under conditions of excessive B availability, this micronutrient is passively transported through the transpiration stream and accumulates in leaves, causing the development of necrotic regions in leaf tips. Some plants have developed adaptive mechanisms to minimize the toxic effects of excessive B accumulation in their tissues. Thus, for instance, in Arabidopsis it has been described an ABA-dependent decrease in the transpiration rate that would restrict B accumulation in aerial plant tissues in response to short-term B toxicity, this effect being mediated by AtNCED3 (which encodes a key enzyme for ABA biosynthesis). The present work aimed to study the possible involvement of ABA in the adjustment of plant water balance and B homeostasis during the adaptive response of Arabidopsis to prolonged B toxicity. For this purpose, Arabidopsis wild-type and the ABA-deficient nced3-2 mutant plants were subjected to B toxicity for 7 days. We show that ABA-dependent stomatal closure is determinant for the adjustment of plant water relations under conditions of prolonged B toxicity. Results suggest that, in addition to the AtNCED3 gene, the AtNCED5 gene could also be involved in this ABA-dependent stomatal closure. Finally, our results also indicate the possible role of endogenous root ABA content in the mechanism of active efflux of B via BOR4 (efflux-type B transporter) from the root to the external environment under excess B conditions.
硼（B）毒性会损害植物的几种代谢和生理过程。在过量 B 供应的条件下，这种微量元素通过蒸腾流被动运输，并在叶片中积累，导致叶片尖端出现坏死区域。一些植物已经发展出适应性机制，以最大程度地减少组织中过量 B 积累的毒性影响。例如，在拟南芥中，已经描述了一种 ABA 依赖性的蒸腾速率降低，这将限制空气中植物组织中 B 的积累，以应对短期 B 毒性，这种效应是由 AtNCED3 介导的（其编码 ABA 生物合成的关键酶）。本研究旨在研究 ABA 在拟南芥对长期 B 毒性的适应性反应中调节植物水分平衡和 B 稳态中的可能作用。为此，将拟南芥野生型和 ABA 缺陷型 nced3-2 突变体植物暴露于 B 毒性下 7 天。我们表明，ABA 依赖性的气孔关闭是在长期 B 毒性条件下调节植物水分关系的决定因素。结果表明，除了 AtNCED3 基因外，AtNCED5 基因也可能参与这种 ABA 依赖性的气孔关闭。最后，我们的结果还表明，内源根 ABA 含量可能在过量 B 条件下通过 BOR4（外排型 B 转运蛋白）从根主动排出 B 的机制中发挥作用。
