Herbicidal Sorbicillinoid Analogs Cause Lignin Accumulation in Aspergillus aculeatusTE-65L

Five new sorbicillinoid derivatives, including (±)-aspersorbicillin A [(±)-1], a pair of enantiomers at C-9, and aspersorbicillins B–D (2–4), together with two known analogs (5and 6) were isolated from the endophytic fungus Aspergillus aculeatusTE-65L. Their structures including absolute configurations were determined by detailed spectroscopic analyses and electronic circular dichroism calculations. The herbicidal activity of sorbicillinoids on the germ and radicle elongation of various weed types was reported for the first time. Compound 1displayed significant herbicidal activity against Eleusine indicagerm elongation (IC50= 28.8 μg/mL), while compound 6inhibited radicle elongation (IC50= 25.6 μg/mL). Both were stronger than those of glyphosate (66.2 and 30.9 μg/mL, respectively). Further transcriptomic and LC-MS/MS metabolomic analysis indicated that 6induced the transcriptional expressions of genes related to the lignin biosynthetic pathway, resulting in lignin accumulation. Transmission electron microscopy confirmed the cell wall thickening of seeds treated with 6, suggesting weed growth inhibition. This study reveals new lead compounds for fabricating natural herbicides and expands the agricultural use of sorbicillinoid analogs.