Toxicity by aluminum is a growth-limiting factor in plants cultivated in acidic soils. This metal also promotes signal transduction pathways leading to the biosynthesis of defense compounds, including secondary metabolites. In this study, we observed that Coffea arabica L. cells that were kept in the dark did not produce detectable levels of caffeine. However, irradiation with light and supplementation of the culture medium with theobromine were the best conditions for cell maintenance to investigate the role of aluminum in caffeine biosynthesis. The addition of theobromine to the cells did not cause any changes to cell growth and was useful for the bioconversion of theobromine to caffeine. During a short-term AlCl₃-treatment (500 μM) of C. arabica cells kept under light irradiation, increases in the caffeine levels in samples that were recovered from both the cells and culture media were evident. This augmentation coincided with increases in the enzyme activity of caffeine synthase (CS) and the transcript level of the gene encoding this enzyme (CS). Together, these results suggest that actions by Al and theobromine on the same pathway lead to the induction of caffeine biosynthesis.

铝的毒性是在酸性土壤中种植的植物的生长限制因素。这种金属还促进信号转导途径，导致防御化合物（包括次级代谢产物）的生物合成。在这项研究中，我们观察到在黑暗中保存的阿拉伯咖啡L.细胞不会产生可检测水平的咖啡因。然而，用光照射和用可可碱补充培养基是研究铝在咖啡因生物合成中作用的最佳细胞维持条件。向细胞中添加可可碱不会引起细胞生长的任何变化，可用于可可碱向咖啡因的生物转化。在短期的AlCl _3处理（500μM）中，阿拉伯糖衣藻如果将细胞保持在光照下，则从细胞和培养基中回收的样品中咖啡因水平均明显升高。此增强正好与咖啡因合酶（CS）和编码这种酶（该基因的转录水平的酶活性增加CS）。总之，这些结果表明Al和可可碱在同一途径上的作用导致咖啡因生物合成的诱导。