Environment sensing in spring-dispersed seeds of a winter annualArabidopsis influences the regulation of dormancy to aligngermination potential with seasonal changes

摘要

Seed dormancy cycling plays a crucial role in the lifecycle timing of many plants. Little isknown of how the seeds respond to the soil seed bank environment following dispersal inspring into the short-term seed bank before seedling emergence in autumn. Seeds of the winter annual Arabidopsis ecotype Cvi were buried in field soils in spring andrecovered monthly until autumn and their molecular eco-physiological responses wererecorded. DOG1 expression is initially low and then increases as dormancy increases. MFT expressionis negatively correlated with germination potential. Abscisic acid (ABA) and gibberellin (GA)signalling responds rapidly following burial and adjusts to the seasonal change in soil temperature.Collectively these changes align germination potential with the optimum climate spacefor seedling emergence. Seeds naturally dispersed to the soil in spring enter a shallow dormancy cycle dominated byspatial sensing that adjusts germination potential to the maximum when soil environment ismost favourable for germination and seedling emergence upon soil disturbance. This behaviourdiffers subtly from that of seeds overwintered in the soil seed bank to spread the periodof potential germination in the seed population (existing seed bank and newly dispersed). Assoil temperature declines in autumn, deep dormancy is re-imposed as seeds become part ofthe persistent seed bank.