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Title: Grain dormancy and light quality effects on germination in the model grass Brachypodium distachyon

Author
item BARRERO, JOSE - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item JACOBSEN, JOHN - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item TALBOT, MARK - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item WHITE, ROSEMARY - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item SWAIN, STEPHEN - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item Garvin, David
item GUBLER, FRANK - Commonwealth Scientific And Industrial Research Organisation (CSIRO)

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2011
Publication Date: 1/1/2012
Citation: Barrero, J.M., Jacobsen, J.V., Talbot, M.J., White, R.G., Swain, S.M., Garvin, D.F., Gubler, F. 2012. Grain dormancy and light quality effects on germination in the model grass Brachypodium distachyon. New Phytologist. 193(1):376-386.

Interpretive Summary: Seed germination is an important process in cereal crops including wheat and barley. In wheat, premature seed germination before crop harvest causes significant crop losses; while in barley, synchronized seed germination is critical for beer production. This study investigated the use of Brachypodium distachyon, a wild grass that is a relative of wheat and barley, as a model to study aspects of seed dormancy and a variety of events that occur during germination. Microscopic analysis revealed that Brachypodium seeds are nearly identical to those of both wheat and barley. After seed harvest, the length of time required before seeds readily germinated varied dramatically between different genotypes of Brachypodium. Further, germination rate was inhibited in the presence of light in all genotypes. Removal of the outer husk covering Brachypodium grains increased germination. Some genes that play an essential role in barley seed germination also appear to be involved in Brachypodium seed germination. A more detailed understanding of the seed germination process will lead to reduced preharvest sprouting losses in wheat and improved beer production efficiency from barley, thus increasing both farm and food industry profitability.

Technical Abstract: Lack of seed dormancy in cereal crops such as barley and wheat is a common problem affecting farming areas around the world, causing losses in yield and quality due to pre-harvest sprouting. Control of seed dormancy has been investigated extensively using various approaches in different species including Arabidopsis and cereals. However, the use of a monocot model plant like Brachypodium distachyon presents opportunities for the discovery of new genes related to seed dormancy that are not present in modern commercial crops. In this work we present an anatomical description of the Brachypodium caryopsis, and we describe the dormancy behavior of six common diploid Brachypodium inbred genotypes. We also study the effect of light quality (blue, red, and far-red) on germination, analyzing changes in ABA levels and in gene expression between a dormant and a non-dormant Brachypodium genotype. Our results indicate that different genotypes display high natural variability in seed dormancy and that the characteristics of dormancy and germination are similar to those found in other cereals. We propose that Brachypodium is an ideal model for studies of seed dormancy in grasses and that can be used to identify new strategies for increasing grain dormancy in crop species.