At CCDM, this is the way we feel about our young barley plants, particularly when searching for genetic resistance to powdery mildew.
You see, when scientists traditionally screen plants for genetic resistance to a disease, they will often use seedlings, to save time and resources.
While this is still a very important method at CCDM, our barley team noticed powdery mildew infecting a seedling plant, but not the adult version of the same plant – and it got the team wondering about resistance in adult plants.
Lead researcher Simon Ellwood said after further tests with adult barley plants from over 1000 exotic lines and landraces, the team discovered not one, but three resistance genes with alternative mechanisms for fighting the barley powdery mildew pathogen, making them the best hope yet of achieving long term resistance to the disease.
“Focusing on later growth stages makes a lot of sense, as this is when yield is at stake,” Simon said.
“Using these resistance genes, breeders can now breed them into their elite barley lines, and in a few years’ time provide growers with cost-effective options for managing powdery mildew.”
Why this discovery is a big one
Resistance to powdery mildew has always been a tough one for breeders. When introducing a resistance gene into barley, it’s often not long before the pathogen mutates to overcome the resistance, and is able to infect the plant again.
Simon said the newly discovered resistance genes will be useful to breeders because of their atypical nature.
“They share features that suggest they operate by different mechanisms to conventional genes to resist powdery mildew, so integrating them into Australian barley cultivars should make for a strong defence that is difficult for the pathogen to overcome,” he said.
“They also appear to be broad-spectrum showing resistance to all powdery mildew pathotypes tested, and they are each single genes which makes them easier for breeders to work with.”
Simon said the new genes will allow breeders to reduce the reliance on the mlo gene, the only current alternative for genetic resistance to barley powdery mildew that was discovered some 40 years ago.
So what will this mean for barley growers?
In the next few years, barley growers will soon have access to varieties with much higher resistance to barley powdery mildew.
Simon said his team have already bulked up seed of lines containing the new resistance genes for breeding companies, to ensure the new genetic material is included in their up-and-coming barley lines.
It will also mean that growers can reduce their reliance on fungicides to manage powdery mildew.
“This is handy, especially as fungicide resistance to Group 3 DMI fungicides is now widespread in areas such as southern WA, where the disease has at times reached epidemic levels,” Simon said.
You see? Growing up is worth waiting for. If only we could tell our younger selves this.
For a copy of the paper, visit http://doi.org/10.1002/tpg2.20129.