铝毒是酸性土壤限制植物生长的主要因子，而低pH是导致铝毒发生的根本因子。一般认为“pH越低，铝毒越严重”，但不少证据表明“pH越高，铝毒越严重”。目前还不清楚这一矛盾的原因。本项目将选用不同植物种类（单子叶植物小麦、玉米、水稻和双子叶植物大豆、荞麦和油茶），采用水培和土培试验，在pH 3.5-5.5条件下比较pH对不同植物种类铝毒的影响差异。据此选出代表性植物和关键pH点，进而深入探究pH对植物铝毒影响的电化学和分子生理机制。电化学机制研究将结合模型计算、核磁共振、质谱和非损伤微测技术，分析生长溶液、根自由空间溶液、根表面铝的形态和活度以及根表面电势，并采用红酵母在细胞水平上阐释电化学机制。分子生理机制研究采用高效液相色谱、定量PCR和RNA测序，研究pH对铝胁迫下有机酸外排、细胞壁组分、耐铝基因表达和转录组学的影响。以期探明酸性条件下pH对不同植物种类铝毒的影响及其机制。

Aluminum (Al) is the primary factor limiting plant growth in acid soils, while pH is the original factor contributing to Al phytotoxicity. It is generally accepted that Al toxicity is much more severe at lower pH, whereas several reports argued that Al becomes much more toxic to plants at higher pH. However, the reason for these contrary opinions is still unknown. The present project will use different types of plants varying in Al tolerance to investigate the effects of pH on plant growth and Al accumulation under acid (pH 3.5-5.5) water and soil culture conditions. Monocotyledonous plants (wheat, maize and rice) and dicotyledonous plants (soybean, buckwheat, oil tea) will be used here. Based on the results of pH effects on Al toxicity of different types of plants, representative plants will be chosen to further explore the mechanisms of electrochemistry and molecular physiology responsible for the effects of pH on Al toxicity. Electrochemical mechanisms will be conducted on the differences in the forms and activities of various Al ions in growth solutions, root free space solutions and root surface among different pHs using chemical analyses, model calculation, NMR (Nuclear Magnetic Resonance), MS (Mass Spectrometry), and NMT (Non-invasive Micro-test Technique) techniques. Simultaneously, Al-tolerant red yeast will also be used to explore electrochemical mechanisms at cell level. The mechanisms of molecular physiology will be conducted on the differences in the organic acid secretion from roots, cell wall components, expression of Al tolerance-related genes and transcriptomics among different pHs under Al stress using HPLC, real-time PCR and RNA sequence. The objective of this project is to clarify the effects of pH on the Al toxicity of different plants and its underlying mechanisms.