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Parental environment changes the dormancy state and karrikinolide response of Brassica tournefortii seeds

Gorecki, M. J., Long, R. L., Flematti, G. R., Stevens, J. C.
Annals of botany 2012 v.109 no.7 pp. 1369-1378
Brassica tournefortii, drought, environmental factors, genetics, seed development, seed dormancy, seed germination, seeds, water stress, weed control, weeds, Western Australia
BACKGROUND AND AIMS: The smoke-derived chemical karrikinolide (KAR1) shows potential as a tool to synchronize the germination of seeds for weed management and restoration. To assess its feasibility we need to understand why seeds from different populations of a species exhibit distinct responses to KAR1. Environmental conditions during seed development, known as the parental environment, influence seed dormancy so we predicted that parental environment would also drive the KAR1-responses of seeds. Specifically, we hypothesized that (a) a common environment will unify the KAR1-responses of different populations, (b) a single population grown under different environmental conditions will exhibit different KAR1-responses, and (c) drought stress, as a particular feature of the parental environment, will make seeds less dormant and more responsive to KAR1. METHODS: Seeds of the weed Brassica tournefortii were collected from four locations in Western Australia and were sown in common gardens at two field sites, to test whether their KAR1-responses could be unified by a common environment. To test the effects of drought on KAR1-response, plants were grown in a glasshouse and subjected to water stress. For each trial, the germination responses of the next generation of seeds were assessed. KEY RESULTS: The KAR1-responses of seeds differed among populations, but this variation was reduced when seeds developed in a common environment. The KAR1-responses of each population changed when seeds developed in different environments. Different parental environments affected germination responses of the populations differently, showing that parental environment interacts with genetics to determine KAR1-responses. Seeds from droughted plants were 5 % more responsive to KAR1 and 5 % less dormant than seeds from well-watered plants, but KAR1-responses and dormancy state were not intrinsically linked in all experiments. CONCLUSIONS: The parental environment in which seeds develop is one of the key drivers of the KAR1-responses of seeds.