Assessment and deployment of a new dwarfing gene in red spring wheat
AWC contribution: $60,000
Start date: December 1, 2016
End date: November 1, 2019
Over the last decade an increasing portion of the Canada Western Red Spring (CWRS) wheat cultivars released have carried height-reducing genes (Rht) while the majority of Canada Prairie Spring (CPS) cultivars have been semi dwarf in stature since the class was created in 1985 with the release of the cultivar HY320. Semi dwarf cultivars have a higher harvest index and tend to respond more efficiently to increased soil fertility and are less prone to lodging. The reduced straw production allows for more rapid combine harvesting which reduces fuel costs and harvest delays that can result in down-grading and quality loss of the wheat crop from weathering. The two dwarfing genes deployed in western Canadian wheat cultivars, Rht-B1b (aka Rht1) and Rht-D1b (aka Rht2) are both semi-recessive and GA-insensitive. Both of these genes have a number of drawbacks. Both genes result in reduced coleoptile lengths (Rebetzke et al., 2007). Reduced coleoptile length can result in poor seedling emergence and thus reduced crop establishment. This is especially a concern when seeding depth is increased due to poor soil moisture conditions near the soil surface, a common occurrence in SK. Both genes have been associated with reduced levels of Type-1 resistance to Fusarium Head Blight (FHB) (Miedaner and Voss, 2008) but increased resistance to spread within the wheat spike (Type 2 resistance). Initial studies indicate that this is likely a pleiotropic effect associated with the GA-insensitivity mechanism (Saville et al., 2012). Originally, it was thought that Rht1 and Rht2 semi-dwarf lines were more prone to FHB infection because of the closer proximity of the spikes to the ground and hence the source of disease inoculum.
- Evaluate near-isogenic lines for potential linkage drag
- Develop a high through-put molecular marker for the Rht18 dwarfing gene
Benefits to producers:
Ultimately the deployment of the rht18 gene could have multiple benefits:
- Reduced costs to Pedigreed wheat seed growers due to reduced labour costs for roguing seed fields.
- Potentially reduced FHB infection levels (relative to currently deployed rht genes) and thus higher grain yields and better grades for the harvested crop.
- Shorter, stronger strawed cultivars that can be managed under higher input conditions (environmental and agronomic).
Pierre Hucl is currently Professor in the Crop Development Centre (Department of Plant Sciences, University of Saskatchewan). Hucl joined the CDC in 1990. Current duties encompass the breeding and genetics of spring wheat, alternative wheat and canary seed. Hucl is the developer or co-developer of over 65 varieties of wheat, canaryseed, dry bean, pea and peanut. He is the author or co-author of over 170 refereed papers and more than 100 conference abstracts and presentations.