University of Queensland, School of Agriculture and Food Sciences, St. Lucia, Queensland 4072, Australia.
Physiol Plant. 2013 Apr;147(4):453-64. doi: 10.1111/j.1399-3054.2012.01674.x. Epub 2012 Sep 13.
The phytotoxicity of Mn is important globally due to its increased solubility in acid or waterlogged soils. Short-term (≤24 h) solution culture studies with 150 µM Mn were conducted to investigate the in situ distribution and speciation of Mn in apical tissues of hydrated roots of cowpea [Vigna unguiculata (L.) Walp. cv. Red Caloona] using synchrotron-based techniques. Accumulation of Mn was rapid; exposure to 150 µM Mn for only 5 min resulting in substantial Mn accumulation in the root cap and associated mucigel. The highest tissue concentrations of Mn were in the root cap, with linear combination fitting of the data suggesting that ≥80% of this Mn(II) was associated with citrate. Interestingly, although the primary site of Mn toxicity is typically the shoots, concentrations of Mn in the stele of the root were not noticeably higher than in the surrounding cortical tissues in the short-term (≤24 h). The data provided here from the in situ analyses of hydrated roots exposed to excess Mn are, to our knowledge, the first of this type to be reported for Mn and provide important information regarding plant responses to high Mn in the rooting environment.
由于锰在酸性或水淹土壤中的溶解度增加，其在全球范围内的植物毒性很重要。本研究采用基于同步加速器的技术，在水培条件下用 150 μM 的 Mn 进行短期（≤24 h）溶液培养实验，以研究豇豆（Vigna unguiculata (L.) Walp. cv. Red Caloona）水生根根尖组织中 Mn 的原位分布和形态。结果表明，Mn 的积累非常迅速；仅暴露于 150 μM Mn 5 分钟，根冠和相关粘液中就会积累大量的 Mn。根冠中的 Mn 浓度最高，数据分析表明，至少有 80%的 Mn(II)与柠檬酸结合。有趣的是，尽管 Mn 毒性的主要部位通常是地上部分，但在短期内（≤24 h），根中 Mn 的浓度并没有明显高于周围的皮层组织。据我们所知，目前所报道的水培条件下过量 Mn 处理的水生根的原位分析数据尚属首例，为植物在生根环境中对高浓度 Mn 的响应提供了重要信息。
