Sorty Ajay Madhusudan, Ntana Fani, Hansen Martin, Stougaard Peter
Department of Environmental Science, Aarhus University, 4000 Roskilde, Denmark.
Microorganisms. 2023 Oct 6;11(10):2504. doi: 10.3390/microorganisms11102504.
Plants exposed to abiotic stress such as drought and salinity produce 1-aminocyclopropane-1-carboxylic acid (ACC) that is converted into the stress hormone ethylene. However, plant growth-promoting bacteria (PGPB), which synthesize the enzyme ACC deaminase, may lower the ACC concentration thereby reducing the concentration of ethylene and alleviating the abiotic stress. The PGPB G20-18 (previously named G20-18) harbors the genes and that encode regulation and synthesis of ACC deaminase, respectively. Regulation of the gene has been investigated in several studies, but so far, it has been an open question whether plants can regulate microbial synthesis of ACC deaminase. In this study, small molecules in wheat root exudates were identified using untargeted metabolomics, and compounds belonging to amino acids, organic acids, and sugars were selected for evaluation of their influence on the expression of the and genes in G20-18. and promoters were fused to the fluorescence reporter gene mCherry enabling the study of and promoter activity. In planta studies in wheat seedlings indicated an induced expression of in association with the roots. Exudate molecules such as aspartate, alanine, arginine, and fumarate as well as glucose, fructose, and mannitol actively induced the promoter, whereas the plant hormone indole-3-acetic acid (IAA) inhibited expression. Here, we present a model for how stimulatory and inhibitory root exudate molecules influence promoter activity in G20-18.
暴露于干旱和盐度等非生物胁迫下的植物会产生1-氨基环丙烷-1-羧酸（ACC），其会转化为胁迫激素乙烯。然而，能够合成ACC脱氨酶的植物促生细菌（PGPB）可能会降低ACC浓度，从而降低乙烯浓度并减轻非生物胁迫。PGPB G20-18（先前命名为G20-18）分别含有编码ACC脱氨酶调节和合成的基因和。多项研究对基因的调控进行了探究，但迄今为止，植物是否能够调控ACC脱氨酶的微生物合成仍是一个悬而未决的问题。在本研究中，利用非靶向代谢组学鉴定了小麦根系分泌物中的小分子，并选择了属于氨基酸、有机酸和糖类的化合物来评估它们对G20-18中基因和表达的影响。将和启动子与荧光报告基因mCherry融合，以便研究和启动子活性。在小麦幼苗上进行的植物体内研究表明，基因在根系部位有诱导表达。天冬氨酸、丙氨酸、精氨酸和富马酸以及葡萄糖、果糖和甘露醇等分泌物分子可积极诱导启动子，而植物激素吲哚-3-乙酸（IAA）则抑制表达。在此，我们提出了一个模型，说明刺激性和抑制性根系分泌物分子如何影响G20-18中的启动子活性。
