Hornbacher Johann, Horst-Niessen Ina, Herrfurth Cornelia, Feussner Ivo, Papenbrock Jutta
Institute of Botany, Leibniz University Hannover, Hannover, Germany.
Albrecht-von-Haller-Institute for Plant Sciences, Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany.
Front Plant Sci. 2022 Oct 31;13:1025969. doi: 10.3389/fpls.2022.1025969. eCollection 2022.
The synthesis of indole-3-acetonitrile (IAN) from the indolic glucosinolate (iGSL) glucobrassicin (GB) is a unique trait of members of the Brassicales. To assess the contribution of this pathway to indole-3-acetic acid (IAA) synthesis under stress conditions, drought stress (DS) experiments with were performed . Analysis of GSLs in DS plants revealed higher contents of GB in shoots and roots compared to control plants. Deuterium incorporation experiments showed the highest turnover of GB compared to all other GSLs during drought conditions. Evidence suggests the involvement of the thioglucosidase BGLU18 in the degradation of GB. The nitrile specifier proteins NSP1 and NSP5 are known to direct the GSL hydrolysis towards formation of IAN. Nitrilases like NIT2 are able to subsequently synthesize IAA from IAN. Expression of , and and contents of GB, IAN and IAA were significantly elevated in DS plants compared to control plants suggesting the increased use of GB as IAA source. Significantly higher contents of reactive oxygen species in DS and ( mutants compared to Col-0 indicate higher stress levels in these mutants highlighting the need for both proteins in DS plants. Furthermore, GB accumulation in leaves was higher in both mutants during DS when compared to Col-0 indicating enhanced synthesis of GB due to a lack of breakdown products. This work provides the first evidence for the breakdown of iGSLs to IAN which seems to be used for synthesis of IAA in DS plants.
从吲哚族硫代葡萄糖苷（iGSL）葡萄糖芥苷（GB）合成吲哚 - 3 - 乙腈（IAN）是十字花目植物成员的一个独特特征。为了评估该途径在胁迫条件下对吲哚 - 3 - 乙酸（IAA）合成的贡献，对[具体植物]进行了干旱胁迫（DS）实验。对DS处理植物中硫代葡萄糖苷（GSL）的分析表明，与对照植物相比，地上部和根部的GB含量更高。氘掺入实验表明，在干旱条件下，与所有其他GSL相比，GB的周转率最高。有证据表明硫代葡萄糖苷酶BGLU18参与了GB的降解。已知腈特异性蛋白NSP1和NSP5可引导GSL水解生成IAN。像NIT2这样的腈水解酶能够随后从IAN合成IAA。与对照植物相比，DS处理植物中[相关基因]的表达以及GB、IAN和IAA的含量显著升高，这表明GB作为IAA来源的使用增加。与Col - 0相比，DS处理的[具体突变体]和[具体突变体]中活性氧物种的含量显著更高，这表明这些突变体中的胁迫水平更高，突出了DS处理植物中这两种蛋白的必要性。此外，在DS处理期间，两个突变体叶片中的GB积累量均高于Col - 0，这表明由于缺乏分解产物，GB的合成增强。这项工作首次证明了iGSLs分解为IAN，而IAN似乎在DS处理的[具体植物]中用于IAA的合成。
