Aluminum (Al) toxicity is a major constraint for crop growth and production in tropical acidic soils, and organic acids (OAs) play a critical role in mitigating Al toxicity. However, the types of OAs secreted and Al tolerance varies across plants. To better understand the mechanisms that rubber trees use to mitigate Al toxicity, Reyan7-33-97 rubber tree tissue culture saplings were treated with different concentrations of AlCl₃ to investigate the secretion of OAs under Al stress, along with the mitigation effects of exogenous OA application. The results showed that the pH value of root exudates was significantly decreased in response to the increase of Al concentration and duration, which resulted in 1.19–2.49 fold increases to total OA levels, particularly oxalic acid as its content was considerately higher than other OAs. When OAs, such as oxalic and malic acids were exogenously applied to Al treatment solutions, the rubber tree chlorophyll content, leaf relative water content and root activity were increased significantly, whereas the Al content in roots and leaves, antioxidant enzyme activities (POD, SOD), MDA and free proline contents decreased significantly in comparison with the Al treatment alone. Oxalic acid was found to be superior to malic acid in alleviating Al toxicity. Taken together, our results demonstrate that root secretion of OAs, particularly oxalic acid, under Al stress is a mechanism for rubber tree Al detoxification.

铝（Al）毒性是热带酸性土壤中作物生长和生产的主要限制因素，有机酸（OAs）在缓解Al毒性方面起关键作用。但是，分泌的OA的类型和铝的耐受性随植物而异。为了更好地了解橡胶树减轻Al毒性的机理，对Reyan7-33-97橡胶树组织培养幼树进行了不同浓度的AlCl _3处理。研究铝胁迫下OAs的分泌，以及外源OA施用的缓解效果。结果表明，随着铝浓度和持续时间的增加，根系分泌物的pH值显着降低，这导致总OA含量增加1.19–2.49倍，尤其是草酸，因为其含量明显高于其他OA。将草酸和苹果酸等OAs外源施用于Al处理溶液时，橡胶树的叶绿素含量，叶片相对水分含量和根系活性显着增加，而根和叶中的Al含量，抗氧化酶活性（POD，SOD） ），与单独的Al处理相比，MDA和游离脯氨酸含量显着降低。发现草酸在减轻Al毒性方面优于苹果酸。两者合计，我们的结果表明，铝胁迫下OAs尤其是草酸的根系分泌是橡胶树Al排毒的一种机制。