Release of Arabidopsis seed dormancy by cold atmospheric plasma relies on cytoplasmic glass transition

Abstract

When mature Arabidopsis thaliana seeds are dormant, their germination is prevented in apparently favourable conditions. This primary dormancy can be released during seed dry storage through a process called after-ripening whose duration can last several months. To reduce this delay, cold atmospheric plasmas (CAP) can be used as sources of reactive oxygen species capable of inducing heterogeneous chemical reactions. While CAP are known to stimulate the germination of various seed species, the relationship between CAP treatments and the amorphous solid state of dry seeds remains unexplored. Here, we demonstrate that seed dormancy can be alleviated using a cold plasma of ambient air and that this alleviation can be amplified for seeds with high water-content (typically 30 %DW) or seeds heated at 60 °C during plasma treatment. Differential scanning micro-calorimetry shows that these characteristics control the glassy/rubbery state of the seed cytoplasm. This technique indicates also that a glass transition to the rubbery state strengthens the CAP effects to alleviate seed dormancy. We propose that lower cytoplasmic viscosity can promote the oxidative signaling induced by CAP which, in turn, improves the germination process.

Treatment of seeds by cold ambient air plasma: combining impedance measurements with water sorption modeling to understand the impact of seed hydration

“…In a prior study dedicated to Arabidopsis seeds, we have established that increasing WC make the seeds enter into an amorphous state, thereby reducing their cytoplasmic viscosity [10]. This so-called 'rubbery state' make the seeds more receptive to the effects of C2AP, especially to release their dormancy.…”

“…Thus, in the medical field, cold plasma at lower dose can induce cell stimulation/proliferation for wound healing while at higher dose it can drive to senescence and cell death for oncology applications [7]. In agriculture and more specifically in the seed sector, cold plasmas are processed to improve germination parameters (vigor, homogeneity, dormancy release, tolerance to water stress) as well as optimal development of seedlings at early stages [8][9][10]. Cold plasmas are also designed to protect seeds from potential fungi (e.g.…”

“…The volume of the gap (V gap ) is defined as the volume of gas (V gas ) with/without the volume of seeds (V seeds ), following equation (9). The gas volume (V gas ) corresponds to the volume of air in the gap, including the regions that are ionized (V pl,on ) and eventually non-ionized (V pl,off ), as suggested in equation (10). Therefore, when seeds are present in the gap, the fraction of non-ionized gas is given by equation (11).…”

Plasma Treatment Modifies Element Distribution in Seed Coating and Affects Further Germination and Plant Growth through Interaction with Soil Microbiome

“…This effect is attributed to the modulation of the amorphous state of the seed cytoplasm. The amorphous properties of seed tissues and the water content within the seeds play a crucial role in regulating cytoplasmic viscosity, which in turn affects oxygen diffusion and the generation of reactive oxygen species (ROS), ultimately leading to dormancy release . In addition, research conducted by Waskow et al demonstrated that plasma treatment can induce significant changes in A.…”

“…The amorphous properties of seed tissues and the water content within the seeds play a crucial role in regulating cytoplasmic viscosity, which in turn affects oxygen diffusion and the generation of reactive oxygen species (ROS), ultimately leading to dormancy release. 21 In addition, research conducted by Waskow et al demonstrated that plasma treatment can induce significant changes in A. thaliana seeds. These changes include seed coat erosion, increased surface roughness, altered chemical composition (e.g., oxidation of carbon), and enhanced hydrophilicity.…”