In alkaline soils, iron (Fe) availability is limited and plants developed different strategies to overcome this constraint. Arabidopsis thaliana follows a reduction-based strategy, in which Fe is reduced at the root surface before plant uptake. Recent studies highlighted the role of phenylpropanoid-derived coumarins in the mobilisation and uptake of Fe in A. thaliana. In this study, we grew the A. thaliana wild-type Col-0 and the f6'h1 mutant defective in phenylpropanoid-derived coumarin synthesis, on six contrasting soils and determined coumarin exudation rates and biochemical changes in the rhizosphere. On the natural alkaline soils, the f6'h1 mutant was not able to grow and growth could only be sustained with regular Fe supply. Root exudates were sampled hydroponically from soil-grown wild-type plants after washing roots. Scopoletin was the predominant coumarin found in the exudates of A. thaliana grown on the different soils. Exudation rates of scopoletin increased with decreasing bioavailability of Fe in soil, with the exception of the acidic soil where plants showed exudation rates similar to the rates measured in alkaline soils. This is the first study reporting exudation of coumarins from A. thaliana grown on a range of natural soils with varying Fe availability.

在碱性土壤中，铁（Fe）的有效性受到限制，植物开发了不同的策略来克服这一限制。拟南芥遵循基于还原的策略，其中在植物吸收前铁在根表面被还原。最近的研究强调了苯丙素类香豆素在拟南芥中铁的动员和吸收中的作用。在这项研究中，我们在六种形成对比的土壤上种植了拟南芥野生型Col-0和f6'h1突变体，该突变体在苯丙氨酸衍生的香豆素合成中存在缺陷，并确定了香豆素的渗出速率和根际中的生化变化。在天然碱性土壤上，f6'h1突变体不能生长，只能通过定期供应铁才能维持生长。根洗净后，从土壤生长的野生型植物中水培取样。斯科波汀是在不同土壤中生长的拟南芥分泌物中发现的主要香豆素。除土壤中铁的渗出速率与碱性土壤中测得的速率相似外，随着土壤中铁的生物利用度的降低，草素的渗出速率增加。这是第一项报告，其报道了生长在各种铁含量不同的天然土壤上的拟南芥中香豆素的渗出。