Mechanisms of seed persistence in blackgrass (Alopecurus myosuroides Huds.)

Seed dormancy is the key factor determining weed emergence in agricultural fields and there is growing interest in weed seeds as a target for weed management. A foremost limitation to this approach is the lack of molecular insight into the mechanisms regulating dormancy in weed seeds. Alopecurus myosuroides (blackgrass) seeds were collected from a wheat field in the UK. At low temperatures, dormant (D) and after-ripened (AR) seeds germinate similarly and at warm temperatures dormancy is enforced. RNAseq analysis at both temperatures for D and AR seeds demonstrated distinct mechanisms, involving abscisic acid and gibberellin signalling, are involved in after-ripening and cold-induced dormancy release. Exogenous application of selected plant growth regulators provided further insight into the phytohormone processes involved in seed dormancy in blackgrass. An untargeted analysis of the transcriptome revealed dormancy-related processes beyond the regulation of germination, such as seed defence processes, which may have potential as targets for weed seedbank management. Our findings suggest that dormancy breaking can occur via multiple independent but connected hormone-mediated mechanisms and provide a case study for the use of next-generation sequencing to uncover the mechanisms involved in seed dormancy in weed and non-model species.