posted on 2024-03-12, 15:41authored byKainan Song, Yutong Ai, Jianshuang Zhou, Baoqing Dun, Qun Yue, Liwen Zhang, Yuquan Xu, Chen Wang
Eco-friendly bioherbicides are urgently
needed for managing the
problematic weed Amaranthus retroflexus. A mass spectrometry- and bioassay-guided screening approach was
employed to identify phytotoxic secondary metabolites from fungi for
the development of such bioherbicides. This effort led to the discovery
of six phytotoxic 16-residue peptaibols, including five new compounds
(2–6) and a known congener (1), from Emericellopsis sp. XJ1056. Their
planar structures were elucidated through the analysis of tandem mass
and NMR spectroscopic data. The absolute configurations of the chiral
amino acids were determined by advanced Marfey’s method and
chiral-phase liquid chromatography-mass spectrometry (LC-MS) analysis.
Bioinformatic analysis and targeted gene disruption identified the
biosynthetic gene cluster for these peptaibols. Compounds 1 and 2 significantly inhibited the radicle growth of A. retroflexus seedlings, and 1 demonstrated
potent postemergence herbicidal activity against A.
retroflexus while exhibiting minimal toxicity to Sorghum bicolor. Structure–activity relationship
analysis underscored the importance of trans-4-hydroxy-l-prolines at both the 10th and 13th positions for the herbicidal
activities of these peptaibols.