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Plant function and evolutionary biology
REVIEW

The central role of the VERNALIZATION1 gene in the vernalization response of cereals

Ben Trevaskis
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A CSIRO Division of Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia. Email: ben.trevaskis@csiro.au

This paper originates from the Peter Goldacre Award 2009 of the Australian Society of Plant Scientists that was received by the author.

Functional Plant Biology 37(6) 479-487 https://doi.org/10.1071/FP10056
Submitted: 12 March 2010  Accepted: 18 April 2010   Published: 20 May 2010

Abstract

Many varieties of wheat (Triticum spp.) and barley (Hordeum vulgare L.) require prolonged exposure to cold during winter in order to flower (vernalization). In these cereals, vernalization-induced flowering is controlled by the VERNALIZATION1 (VRN1) gene. VRN1 is a promoter of flowering that is activated by low temperatures. VRN1 transcript levels increase gradually during vernalization, with longer cold treatments inducing higher expression levels. Elevated VRN1 expression is maintained in the shoot apex and leaves after vernalization, and the level of VRN1 expression in these organs determines how rapidly vernalized plants flower. Some alleles of VRN1 are expressed without vernalization due to deletions or insertions within the promoter or first intron of the VRN1 gene. Varieties of wheat and barley with these alleles flower without vernalization and are grown where vernalization does not occur. The first intron of the VRN1 locus has histone modifications typically associated with the maintenance of an inactive chromatin state, suggesting this region is targeted by epigenetic mechanisms that contribute to repression of VRN1 before winter. Other mechanisms are likely to act elsewhere in the VRN1 gene to mediate low-temperature induction. This review examines how understanding the mechanisms that regulate VRN1 provides insights into the biology of vernalization-induced flowering in cereals and how this will contribute to future cereal breeding strategies.

Additional keywords: barley, flowering, wheat.


Acknowledgements

I thank my friends and colleagues Steve Swain, Aaron Greenup, Sarah Fieg, Sandra Oliver and Megan Hemming for reading drafts of this manuscript and providing constructive suggestions. I also gratefully acknowledge both the Commonwealth Scientific and Industrial Research Organisation, and the Grains Research and development Corporation for long-term support of this research.


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