Heads of wheat and wheat grain.

Heads of wheat and wheat grain.

Understanding flowering time in cereals

CSIRO Plant Industry scientists are unravelling the genetic mechanisms involved in flowering of cereals as part of a Grains Research and Development Corporation project.

  • 29 January 2009 | Updated 14 October 2011


The VERNALIZATION1 gene (VRN1) promotes flowering and inactivates frost tolerance in the temperate cereals, such as wheat, barley, oats and rye. 

Some temperate cereal varieties require prolonged cold (or vernalization) to flower, and in these varieties VRN1 is activated during winter to promote flowering and to inactivate frost tolerance in spring.  In other varieties, VRN1 is active without prolonged cold.  These varieties do not need to over-winter to flower and can be grown in warm climates, but typically have reduced frost tolerance.

The project

As part of the Grains Research and Development Corporation funded project “New resources for breeding for heading date and improved frost tolerance” CSIRO scientists screened large numbers of wheats and barleys from the Australian Winter Cereal Collection (AWCC) for diversity in the VRN1 gene. 

Researchers mainly screened for changes (deletions or insertions) in a specific part of the VRN1 gene sequence, the first intron. These changes had previously been associated with activation of VRN1 and the loss of the requirement for vernalization to trigger flowering. 

This approach has allowed scientists to identify several different versions (alleles) of VRN1 which have different effects on VRN1 activity and on flowering time.  These different alleles of VRN1 are described in an upcoming publication (Hemming et al. 2009, in preparation).

Genotype data

Although the primary focus of the study was to screen for novel alleles of VRN1, scientists also screened large numbers of wheats and barleys for VRN1 and also VRN2 in barley.  This information is provided below.

Barley Genotype data
Wheat Genotype data
DNA extraction protocol

These datasets allow different flowering behaviours to be identified amongst different barleys and wheats held at the AWCC.  For some lines, the data is preliminary as the seeds are not homogenous.

‘Landraces’ (different types of the same variety) were frequently found to carry different types of VRN1. The same is true for some modern varieties.  Additionally, technical and operator error may have reduced the accuracy of the genotyping data.  Finally, other genes (eg. VRN3), which have not been examined, might also influence flowering behaviour.

Despite these limitations, the genotype data does allow selection for particular flowering behaviour. For example, a large number of potential winter wheats can now be selected from amongst the AWCC collection.  Similarly, large numbers of winter, spring or facultative barleys (early flowering in long days) could be identified using these genotype data. 

More research is needed, such as subsequent flowering time tests or re-genotyping (multiple seeds per line, or single seed descent) to confirm the initial genotype scores.