Antimicrobial coumarins and proteins to functionalizing the leaf surface for plant protection

大豆是世界上最重要的农作物之一。它的主要疾病是由真菌豆薯层锈菌（Phakopsora pachyrhizi）引起的亚洲大豆锈病（SBR）。在主要的大豆种植区（巴西、阿根廷和美国），SBR每年造成数十亿欧元的产量损失。大豆的抗性优良品种不可用，并且栽培实践以及化学或生物控制措施无效、昂贵或潜在有害。因此，需要用于SBR控制的替代措施。我们以前的研究表明，向日葵和拟南芥对SBR的有效非宿主抗性可能是由于东莨菪内酯的积累。香豆素有效地抑制了豆薯疫霉孢子的萌发。然而，大豆中似乎不存在东莨菪碱。在转基因大豆植物中重建东莨菪内酯生物合成略微降低了对SBR的敏感性。但是，高浓度的东莨菪内酯会损害植物。因此，我们希望通过分泌东莨菪素到叶表面来有效地对抗豆薯疫霉孢子而不伤害植物来转移向日葵对大豆的非寄主抗性。我们打算对isoscopoletin做同样的事情，与其他香豆素相比，它在光照下非常稳定，并有效地对抗P. pachyrhizi孢子。此外，我们的目标是重建sideretin在转基因植物的生物合成，并研究其作用方式。最后，在一个互补的方法，我们想合成和分泌到叶片表面的抗菌蛋白，有助于向日葵非宿主耐SBR。表面积累抗微生物香豆素和/或蛋白质的大豆植物有希望用于可持续的全球大豆生产。

Soybean is one of the most important crops worldwide. Its major disease is Asian soybean rust (SBR) that is caused by the fungus Phakopsora pachyrhizi. In the major soybean-growing areas (Brazil, Argentina, and the USA), SBR causes annual yield losses of several billion Euros a year. Resistant elite varieties of the soybean are not available and cultivation practices as well as chemical or biological control measures ineffective, expensive, or potentially harmful. Therefore, alternative measures for SBR control are needed. We previously showed that the effective nonhost resistance of sunflower and Arabidopsis to SBR could be due to the accumulation of scopoletin. The coumarin effectively inhibits the germination of P. pachyrhizi spores. Scopoletin, however, seems to be absent from soybean. Reconstituting scopoletin biosynthesis in transgenic soybean plants slightly reduced the susceptibility to SBR. But, high scopoletin concentrations damaged the plants. We, therefore, would like to transfer the nonhost resistance of sunflower to soybean by secreting scopoletin to the leaf surface to effectively fight P. pachyrhizi spores without harming the plant. We intend to do the same for isoscopoletin, that in contrast to other coumarins is very stable in the light and effectively fights P. pachyrhizi spores. In addition, we aim to reconstitute the biosynthesis of sideretin in transgenic plants and investigate its mode of action. Finally, in a complementary approach we would like to synthesize and secrete to the leaf surface antimicrobial proteins that contribute to sunflower nonhost resistance to SBR. Soybean plants that surface-accumulate antimicrobial coumarins and/or proteins are promising for sustainable worldwide soybean production.