Improving the whole genetic package to deliver environmentally-resilient oilseed rape performance is the focus of Dekalb’s variety development programme, which aims to provide growers with tailored solutions rather than just traits.
French breeding programme leader Julien Binet explains: “We have introduced even greater diversity at the heart of our oilseed rape breeding with a major expansion of our di-haploid laboratory which creates genetically pure lines from single pollen grains. “At the same time, we are employing the genome-wide selection approach that has revolutionised livestock breeding in recent years.”
High-capacity genetic mapping allows us to identify whole blocks of genes associated with our most successful hybrids in different environments and track these within our parent lines.
“We are then able to estimate the overall breeding value of hybrid parents for the outcomes we want. This enables us to tailor our variety development very much more precisely for different environments. Modelling tools and technologies from corn, canola, soybean, wheat and rice breeding are proving invaluable to us here. And we are thinking outside the traditional plant breeding box model by bringing animal breeding expertise into our team.”
Alongside marker-assisted selection to introduce and fix new traits involving relatively few genes into Dekalb lines, this whole genome approach is giving the company the ability to much more reliably develop hybrids with combinations of characters governed by many genes working together; characters involved in more complex traits such as early plant establishment, environmental stress tolerance and broad-spectrum disease resistance, that are far less responsive to traditional marker-assisted techniques.
Fundamental Completely untreated breeding and selection trials run across a range of stress situations in Europe are fundamental to these advances, says UK and Nordics breeding leader Matthew Clarke.
“It is easy to underestimate the value of these. But we continue testing all our emerging hybrids as well as parent lines without any crop protection support right through to their NL2 stage of development. And we deliberately do so in situations known to present particular disease, pest and other environmental challenges.”
“This allows us to only bring forward hybrids we are confident have the underlying genetic strength to perform consistently well for their particular environments. We do not consider many of the tolerances we know our varieties possess as major traits. Rather, we consider them to be essential backgrounds of environmental resilience growers can rely on.”
“At the same time this selection work allows us to identify the key genetic elements most associated with the resilience we identify in particular environments to feed back into our genome-wide selection programme. It is a circular process of continual all-round improvement.”
Unlike principal traits such as phoma resistance, light leaf spot resistance and pod shatter resistance which provide genetic insurance against losses, the two breeders regard the improvement in environmental resilience they are building into varieties as yield-additive, more than anything else.
“As a hugely complex trait, yield is not something we can reliably breed for directly,” says Mr Binet.
“And if we put too much general emphasis on breeding for yield, we can easily dilute important traits, the loss of which may prove catastrophic under the extremes of climate we are seeing these days.”
“By constantly adding to the platform of traits we have been able to fix in our parent lines and steadily building hybrids we know to be especially well-adapted to particular environments we can achieve the steady, low-risk, high-reliability performance progress growers are asking us for. We can also provide varieties purpose-built to perform under specific regimes, like early or later drilling, light or deep soils, or restrictive nitrogen regimes.”