Induction of agricultural weed seed germination by smoke and smoke‑derived karrikin(KAR1), with a particular reference to Avena fatua L.

Plant-derived smoke, its water extract—the smoke water (SW), and karrikin (KAR₁) present in the smoke stimulate seed germination in plants from fire-prone and fire-free areas, including weeds and cultivated plants. There are also plants, the seeds of which can respond only to smoke, but not to KAR₁, and vice versa. Smoke and/or KAR₁ can be applied in horticulture, agriculture, and revegetation. This review describes effects of smoke and KAR₁ on weed seed germination and focuses mainly on the recent knowledge about the physiological role of these factors in dormancy release and germination of Avena fatua caryopses. The involvement of gibberellins, ethylene, and abscisic acid (ABA) in the response to smoke or KAR₁ is discussed. Effects of smoke or KAR₁ on the contents of reactive oxygen species (ROS), non-enzymatic antioxidants, and activity of the enzymes participating in ROS removal are presented. Cell cycle activity in the response to SW and KAR₁ is also considered. Effects of KAR₁ on thermodormancy release in A. fatua caryopses are highlighted, as well.