Cuminaldehyde, a cumin seed volatile component, induces growth inhibition, overproduction of reactive oxygen species and cell cycle arrest in onion roots

Abstract

Phytogrowth-inhibitory activities of volatile compounds produced by cumin seeds (Cuminum cyminum L.) and phytotoxic effects induced by the compound with strong phytotoxic activity were investigated as a first step to elucidate the mode of action of the compounds. By gas chromatography-mass spectrometry (GC–MS) analyses, α-pinene (2,6,6-trimethylbicyclo[3.1.1]hept‑2-ene)), β-pinene (6,6-dimethyl-2-methylenebicyclo[3.1.1]heptane), cuminaldehyde (4-(1-methylethyl)benzaldehyde), and p-cymene (1-methyl-4-(1-methylethyl) benzene) were identified as volatile compounds from the cumin seeds. Among them, cuminaldehyde showed the highest phytotoxic activity in lettuce seedlings. The compound also exhibited broad-spectrum growth inhibitory activity against dicot and monocot species; however, maize, wheat, common bean, and Indian jointvetch were relatively tolerant to it. In roots of onion, a sensitive species to cuminaldehyde, the compound induced a decrease in the viability and population of mitotic cells and an increase in reactive oxygen species (ROS) production, programmed cell death (PCD), and loss of membrane integrity, in a concentration-dependent manner. Cuminaldehyde-induced growth inhibition in onion roots may be due to ROS overproduction, which may induce oxidative DNA damage, cell cycle arrest, and loss of membrane integrity, resulting in cell death including PCD and necrosis.