Laboratory of Natural Products Pesticides, College of Plant Protection, Southwest University, Chongqing, China.
Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Barcelona, Spain.
Pest Manag Sci. 2021 Nov;77(11):5170-5185. doi: 10.1002/ps.6557. Epub 2021 Aug 16.
Ralstonia solanacearum is one of the most devastating pathogens affecting crop production worldwide. The hydroxycoumarins (umbelliferone, esculetin and daphnetin) represent sustainable natural bioresources on controlling plant bacterial wilt. However, the antibacterial mechanism of hydroxycoumarins against plant pathogens still remains poorly understood.
Here we characterized the effect of three hydroxycoumarins on the transcriptome of R. solanacearum. All three hydroxycoumarins were able to kill R. solanacearum, but their antibacterial activity impacted differently the bacterial transcriptome, indicating that their modes of action might be different. Treatment of R. solanacearum cultures with hydroxycoumarins resulted in a large number of differentially expressed genes (DEGs), involved in basic cellular functions and metabolic process, such as down-regulation of genes involved in fatty acid synthesis, lipopolysaccharides biosynthesis, RNA modification, ribosomal submits, oxidative phosphorylation and electrontransport, as well as up-regulation of genes involved in transcriptional regulators, drug efflux, and oxidative stress responses. Future studies based on in vitro experiments are proposed to investigate lipopolysaccharides biosynthesis pathway leading to R. solanacearum cell death caused by hydroxycoumarins. Deletion of lpxB substantially inhibited the growth of R. solanacearum, and reduced virulence of pathogen on tobacco plants.
Our transcriptomic analyses show that specific hydroxycoumarins suppressed gene expression involved in fatty acid synthesis, RNA modification, ribosomal submits, oxidative phosphorylation and electrontransport. These findings provide evidence that hydroxycoumarins inhibit R. solanacearum growth through multi-target effect. Hydroxycoumarins could serve as sustainable natural bioresources against plant bacterial wilt through membrane destruction targeting the lipopolysaccharides biosynthesis pathway.
茄青枯雷尔氏菌是全球范围内影响作物生产的最具破坏性的病原体之一。羟基香豆素（伞形酮、七叶灵和瑞香素）是控制植物细菌性萎蔫的可持续天然生物资源。然而，羟基香豆素对植物病原体的抗菌机制仍知之甚少。
在这里，我们描述了三种羟基香豆素对茄青枯雷尔氏菌转录组的影响。三种羟基香豆素都能杀死茄青枯雷尔氏菌，但它们的抗菌活性对细菌转录组的影响不同，表明它们的作用模式可能不同。用羟基香豆素处理茄青枯雷尔氏菌培养物会导致大量差异表达基因（DEGs），这些基因参与基本的细胞功能和代谢过程，如脂肪酸合成、脂多糖生物合成、RNA 修饰、核糖体亚基、氧化磷酸化和电子传递相关基因下调，以及转录调控因子、药物外排和氧化应激反应相关基因上调。未来的研究基于体外实验，旨在研究导致羟基香豆素引起茄青枯雷尔氏菌细胞死亡的脂多糖生物合成途径。lpxB 的缺失显著抑制了茄青枯雷尔氏菌的生长，并降低了病原体对烟草植物的毒力。
我们的转录组分析表明，特定的羟基香豆素抑制了脂肪酸合成、RNA 修饰、核糖体亚基、氧化磷酸化和电子传递相关基因的表达。这些发现为羟基香豆素通过多靶点效应抑制茄青枯雷尔氏菌生长提供了证据。羟基香豆素可以通过靶向脂多糖生物合成途径破坏细胞膜，作为防治植物细菌性萎蔫的可持续天然生物资源。
