Seed dormancy breaking treatments for Cynara cardunculus using reactive oxygen species and alternating temperatures

Overview

Cynara cardunculus L. is a versatile perennial crop with three interfertile varieties (artichoke, leafy cardoon, and wild cardoon) used for food, biomass, and bioactive compounds. A major barrier to its full agricultural exploitation is irregular and inconsistent seed germination caused by physiological dormancy. This research program develops targeted seed treatments to break dormancy and significantly improve germination rates, with initial work on wild cardoon intended for transfer to artichoke hybrids.

Technical specifications

Core approach:

• Application of alternating temperatures (ATs) as an environmental cue to terminate dormancy
• Use of reactive oxygen species (ROS) donors in germination media to stimulate germination
• Combination of molecular and hormonal analyses to understand and optimize treatments

Key findings and mechanisms:

• ROS donors in germination medium significantly increase germination rates (p < 0.05)
• ROS synthesis and signaling inhibitors reduce germination (p < 0.001), confirming the central role of ROS in dormancy regulation
• Alternating temperatures activate key pathways in ROS homeostasis, including upregulation of RBOH and CAT genes
• ATs promote ethylene metabolism and balanced ROS synthesis and degradation
• Cell wall weakening genes (EXPs) are expressed during AT treatment
• ATs help maintain the oxidative window, preventing tissue damage
• Temperature contributes to achene dormancy alleviation through dry afterripening

Planned validation activities:

• Testing different ROS donor compounds to identify the most effective pretreatment for wild cardoon
• Extending the best-performing treatment to dormant seeds of artichoke and leafy cardoon
• Anatomical localization of ROS compound concentration within achenes
• Analysis of GA/ABA hormone ratio during ROS treatments
• Gene expression profiling of achenes exposed to ROS treatments

Technology readiness level

The project is at an advanced research stage with strong preliminary validation. Laboratory evidence confirms that both alternating temperatures and ROS-based treatments effectively reduce seed dormancy in C. cardunculus, supported by statistically significant germination data and molecular pathway analyses. The research team has established mechanistic understanding of the hormonal and genetic regulation involved. Next steps focus on optimizing ROS donor selection, extending the approach across all three Cynara varieties, and completing detailed molecular characterization before potential transfer to commercial seed treatment applications.