Light and Alternating Temperatures Release Seed Dormancy in the Invasive Dipsacus fullonum L. Through ROS Homeostasis and ABA Regulation.

Seeds have developed mechanisms to perceive environmental signals, such as light and temperature, which govern germination and enhance the chance of seedling establishment. This study examined the foundations of light and temperature sensitivity in the seed dormancy release of a common weed, Dipsacus fullonum. By screening six accessions from two different regions, we identified two unique germination behaviors: one sensitive to environmental stimuli and one neutral to them. In the sensitive accession, ABA is crucial for regulating dormancy release, as it accumulates in seeds subjected to darkness, while it decreases under other conditions. We observed a rise of reactive oxygen species (ROS) under conditions that stimulate germination and highlighted that their presence enhanced germination even in the absence of light. This study employed a long-read RNA-seq technology to examine the regulation of key genes associated with germination. We identified the essential nodes in this process: DfPIF1, which maintains the dormancy state in darkness at constant temperatures mainly by promoting ABA biosynthesis and signaling, and antioxidant enzymatic machinery, DfMSD1, DfCSD2, DfAPX, and DfPRX1, whose activity regulates ROS homeostasis, promoting or inhibiting germination. This study provides novel mechanisms that regulate seed germination in weeds, specifically involving ABA regulation and ROS in response to environmental stimuli.