Allelochemical from Leaves of <i>Juglans mandshurica</i> Maxim. And Its Transcriptomic Effects in Plants

Weeds have a significant effect on agricultural productivity; thus, sustainable herbicide alternatives are necessary. Inspired by natural processes where bioactive compounds from fallen leaves inhibit nearby plant growth, this study is the first to isolate and identify 2Z-decaprenol as an allelochemical from <i>Juglans mandshurica</i> Maxim. Using a soil-based bioactivity model, bioassay-guided fractionation confirmed that <i>n</i>-hexane fraction plays an important role in suppressing <i>Nicotiana tabacum</i> Linn. seedling growth, with 2Z-decaprenol isolated as the active compound. Treatment with 2Z-decaprenol reduced plant weight, shoot length, and root length and induced root curling and detachment. Transcriptomic analysis of <i>Arabidopsis thaliana</i> seedlings treated with 2Z-decaprenol revealed extensive transcriptional reprogramming, with enrichment in secondary metabolite biosynthesis, cell wall modification, and asymmetric cell division pathways. Concurrently, pathways associated with protein processing in the endoplasmic reticulum and stress response mechanisms, including jasmonic acid signaling, were suppressed. These findings highlight the potential application of 2Z-decaprenol as an eco-friendly bioherbicide.