Alleviation of dormancy by reactive oxygen species in Bidens pilosa L. seeds

Bidens pilosa L. is a weedy species in the Asteraceae producing dimorphic one-seeded fruits, with longer black seeds centrally situated in the capitulum, and shorter dormant brown peripheral seeds. While the outer seeds germinate readily after seed shedding, the shorter seeds possess various dormancy mechanisms, including requirements for after-ripening and red light. Here we show that applications of reactive oxygen species (ROS)-generating reagents can remove dormancy in the short seeds. In B. pilosa, reagents that generate hydroxyl radicals (OH) and superoxide (O2¯) partially replaced the requirement for after-ripening, while O2¯ generation replaced the requirement for red light. Hence, ROS appear to be implicated in the alleviation of dormancy in the seeds of B. pilosa.