Plasticity in plant dispersal traits can maximise the ability of a plant species to survive in stressful environments during colonization. Aethionema arabicum (Brassicaceae) is a dimorphic annual species that is hypothesized to survive stressful conditions during colonization due to adaptive plasticity in life-phase (vegetative vs sexual) and fruit morph (dehiscent [DEH] vs indehiscent fruits [IND]). We tested for adaptive plasticity in life-phase and fruit morphs along laboratory environmental stress gradients found in the natural habitats of Ae. arabicum. We considered optimal environmental conditions (750-2000 m above sea level) to be those that resulted in the following fitness parameters: higher biomass and a higher total number of fruits compared to stressful habitats. We found evidence of plasticity in life-phase and fruit-morph along a stressful environmental gradient. High hydrothermal stress proportionally increased the number of dehiscent morphs and non-dormant seeds germinating in autumn. This offsets natural phenology towards dry and cold winter (less hydrothermal stress), yielding fewer fruits that dehisce in the next generation. We conclude that the plastic responses of Ae. arabicum to natural stress gradients constitute a strategy of long-term adaptive benefits and favouring potential pathways of colonisation of the optimal habitat.

• MeSH
• Brassicaceae růst a vývoj   fyziologie   MeSH
• ekosystém MeSH
• fyziologická adaptace MeSH
• fyziologický stres MeSH
• klíčení MeSH
• ovoce růst a vývoj   MeSH
• semena rostlinná růst a vývoj   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Heteromorphic diaspores (fruits and seeds) are an adaptive bet-hedging strategy to cope with spatiotemporally variable environments, particularly fluctuations in favourable temperatures and unpredictable precipitation regimes in arid climates. We conducted comparative analyses of the biophysical and ecophysiological properties of the two distinct diaspores (mucilaginous seed (M+ ) vs indehiscent (IND) fruit) in the dimorphic annual Aethionema arabicum (Brassicaceae), linking fruit biomechanics, dispersal aerodynamics, pericarp-imposed dormancy, diaspore abscisic acid (ABA) concentration, and phenotypic plasticity of dimorphic diaspore production to its natural habitat and climate. Two very contrasting dispersal mechanisms of the A. arabicum dimorphic diaspores were revealed. Dehiscence of large fruits leads to the release of M+ seed diaspores, which adhere to substrata via seed coat mucilage, thereby preventing dispersal (antitelechory). IND fruit diaspores (containing nonmucilaginous seeds) disperse by wind or water currents, promoting dispersal (telechory) over a longer range. The pericarp properties confer enhanced dispersal ability and degree of dormancy on the IND fruit morph to support telechory, while the M+ seed morph supports antitelechory. Combined with the phenotypic plasticity to produce more IND fruit diaspores in colder temperatures, this constitutes a bet-hedging survival strategy to magnify the prevalence in response to selection pressures acting over hilly terrain.

• MeSH
• biofyzikální jevy * MeSH
• biomechanika MeSH
• Brassicaceae fyziologie   MeSH
• ekosystém MeSH
• fyziologická adaptace * MeSH
• klíčení fyziologie   MeSH
• ovoce fyziologie   MeSH
• půda MeSH
• semena rostlinná fyziologie   MeSH
• šíření semen fyziologie   MeSH
• vítr MeSH
• voda MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The timing of seed germination is crucial for seed plants and is coordinated by internal and external cues, reflecting adaptations to different habitats. Physiological and molecular studies with lettuce and Arabidopsis thaliana have documented a strict requirement for light to initiate germination and identified many receptors, signaling cascades, and hormonal control elements. In contrast, seed germination in several other plants is inhibited by light, but the molecular basis of this alternative response is unknown. We describe Aethionema arabicum (Brassicaceae) as a suitable model plant to investigate the mechanism of germination inhibition by light, as this species has accessions with natural variation between light-sensitive and light-neutral responses. Inhibition of germination occurs in red, blue, or far-red light and increases with light intensity and duration. Gibberellins and abscisic acid are involved in the control of germination, as in Arabidopsis, but transcriptome comparisons of light- and dark-exposed A. arabicum seeds revealed that, upon light exposure, the expression of genes for key regulators undergo converse changes, resulting in antipodal hormone regulation. These findings illustrate that similar modular components of a pathway in light-inhibited, light-neutral, and light-requiring germination among the Brassicaceae have been assembled in the course of evolution to produce divergent pathways, likely as adaptive traits.

• MeSH
• Brassicaceae fyziologie   účinky záření   MeSH
• exprese genu účinky záření   MeSH
• gibereliny metabolismus   MeSH
• klíčení účinky záření   MeSH
• kyselina abscisová metabolismus   MeSH
• rostlinné geny * MeSH
• sluneční záření * MeSH
• transkriptom účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH