Bruceine D, the main active ingredient of Brucea javanica (L.) residue inhibits the germination of Bidens pilosa L. seeds by suppressing phenylpropanoid biosynthesis

Bidens pilosa L. is a troublesome weed that affects the survival and production of crops. Our previous study showed that Brucea javanica (L.) residue has potent herbicidal activity against B. pilosa, and Bruceine D is the main active ingredient in the B. javanica residue. This study showed that Bruceine D significantly inhibited the germination of B. pilosa seeds, especially root hair, and it likewise showed a dose-dependent effect. Transcriptome results showed that phenylpropanoid biosynthesis was inhibited by Bruceine D (10 μg/mL). The expression of PAL, C4H, and 4CL genes were dynamic, whereas genes encoding COMT and POD remained significantly downregulated during Bruceine D treatment. The activities of these enzymes exhibited similar results. At the same time, the contents of several phenylpropanoid biosynthesis metabolites, including flavonoids and lignin, decreased in response to Bruceine D. Our results highlight the use of Bruceine D as a good candidate to develop bioherbicide.