Abstract
Seed dormancy determines the timing of seed germination and may be released by dry storage, also referred to as after-ripening. Studies on dormancy-release mechanisms are often hampered by the long after-ripening requirements of seeds. After-ripening is thought to be mainly caused by oxidative processes during seed dry storage. These processes are also the main cause of seed ageing. Increasing partial oxygen pressure through the elevated partial pressure of oxygen (EPPO) system has been shown to mimic and accelerate dry seed ageing. In this study, we investigated whether the EPPO system may also release primary seed dormancy in Arabidopsis thaliana. EPPO mimics dry after-ripening at the genetic level, as quantitative trait locus (QTL) analysis after EPPO treatment identified the DELAY OF GERMINATION loci DOG1, DOG2, and DOG6 that were first described in a study using dry after-ripening to release seed dormancy. QTL analysis also showed that dormancy release by cold stratification (another common method to break seed dormancy) partly overlaps with release by after-ripening and EPPO treatment. We conclude that EPPO is an appropriate method to mimic and accelerate dormancy release and, as such, may have applications in both research and industry.
Highlights
The seed is the unit for propagation, dispersal, and survival of seed plants
To investigate whether the effect of elevated partial pressure of oxygen (EPPO) was due to the elevated partial pressure of oxygen (pO2), a treatment with 8 MPa of pure nitrogen gas (N2) was performed (Fig. 1); similar to the EPPO air treatment, the pressure was increased to 20 MPa after 28 d of storage at 8 MPa
The EPPO treatments as performed in our experiments did not result in visually aged seeds, in that we did not observe morphologically aberrant seedlings, e.g. stunted root growth or discoloration of the cotyledons, which are the first signs of seed ageing in cruciferous species (ISTA, 2018)
Summary
Orthodox seeds can withstand drying and can survive over time and be dispersed over distance.The seed has to germinate and establish a seedling in order to grow and propagate. As plants in temperate regions often disperse their seeds in autumn, immediate germination of the seed would cause it to grow in winter, decreasing the chance of seedling survival and propagation. Arabidopsis thaliana displays coat-enhanced physiological dormancy in which the balance between the hormones abscisic acid (ABA; germination-inhibiting) and gibberellins (GAs; germination-promoting) is key in determining the germination status
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