Finding the balance between frost tolerance and flowering time in wheat

Project summary

Australian grain breeders now have new lines of wheat and barley with different versions of the major heading-date genes (the genes that control the length of time it takes for the crop to produce grain). Breeders can use these new lines to breed varieties that have a wider range of flowering dates and are potentially more frost tolerant.

Outcomes

• The research produced a set of wheat and barley lines with different versions of the heading-date genes, VRN1 and PPD1, introduced into the best wheat and barley lines available.
• By growing these lines at different field sites, with different sowing times, researchers can determine the optimal flowering time genotype for Australian growing regions. This information has the potential to increase yields through optimisation of flowering behaviour and improving frost tolerance.
• The new knowledge about the VRN1 and PPD1 genes is useful to researchers and pre-breeders, as it contributes to the development of future wheat and barley varieties for growers.

Background

The time of year that a cereal crop flowers and produces grain is known as the heading date. Flowering must coincide with favourable conditions to maximise yield and grain quality, so this is a key trait of cereal varieties.

Varieties that have a wide range of heading dates will suit a number of different agricultural environments around Australia and will benefit growers through increased yield and better grain quality. Improved frost tolerance will safeguard against the damage and yield losses caused by late frost events.

This project aimed to generate lines of wheat and barley that differ for flowering behaviour and potentially reproductive frost tolerance. Two major flowering-time genes VRN1 and PPD1 have been found to be linked to this behaviour.  VRN1 determines whether vernalization (prolonged cold during winter) is required for rapid flowering, whereas PPD1 controls day length sensitivity. The optimal combination of these genes and an appropriate sowing date is critical for maximal yield. Consequently, these genes are important determinants of where and when cultivars can be grown. Additionally, both genes influence the risk of frost damage by determining the likelihood that flowering (a frost sensitive growth stage) will occur at a time of year when frosts are likely. There is evidence that flowering time genes also influence frost tolerance, so that some genotypes can better withstand frosts at the flowering stage.

The new lines of wheat and barley with different versions of VRN1 and PPD1 developed by this project will be valuable tools for future research. The lines will allow pre-breeders to identify the optimal flowering behaviour for a particular region so that the corresponding genotype can then be targeted in breeding programs. The lines will also allow better modelling of how interactions between genotype and environmental factors influence heading date. These lines will also be a useful tool for future studies examining the relationship between phenology (the timing of different developmental events) and other traits of interest, such as reproductive frost tolerance.

Related projects

UA00063 – Breeding for frost tolerance in barley

UA00100 – Nationally coordinated frost trials – southern region

UA00114 – Frost tolerance in wheat