Crop diseases can have serious effects on economies and human health. Dr Fiona Doohan is looking at new ways to protect crops from disease-causing bugs, and maybe even use some of those bugs to our advantage. Claire O’Connell found out more.
What did you eat for your most recent meal? That fare likely contained ingredients from a crop plant, or an animal that ate crop plants along the way. And while we might not need the thermostat on full blast at the moment, come winter many of us will be warmed courtesy of plant-based fuels. So what happens when the plants we rely on get hit by disease?
Dr Fiona Doohan, a senior lecturer at University College Dublin (UCD)’s School of Biology and Environmental Science and associate director of UCD’s Earth Institute, is looking for new ways to help protect agricultural plants against the microbial pathogens (disease-causing organisms) that prey on them.
“Plants are very important for food, fuel and amenities, and diseases caused by micro-organisms can mean billions of dollars in losses of yield,” she explains. “That in turn can threaten food security and increase the cost of food, and in some cases the food may be contaminated with toxins, so there could be health implications, too.”
Traditional chemicals losing their punch
Chemicals offer some options to keep agricultural pests at bay, but increasingly we need other approaches, explains Doohan. “The whole landscape of controlling plant diseases is about to change,” she says. “We now have diseases we have no control for – some new diseases and some that have been around for a long time – where the traditional chemicals don’t work.”
Some plant pathogens are becoming more resistant to chemicals, and environmental regulations and constraints are also dissuading industry from developing many new chemicals to control plant diseases, according to Doohan. “The upshot is that there are fewer chemicals that can be used, and we have to look at more sustainable and environmentally friendly (alternatives),” she says.
Informed breeding to tackle disease
So she and her colleagues at UCD are exploring a more ‘internal’ approach. They are looking at how plants respond to pathogens at a molecular level and working out the key genes involved in plant defences.
“We look at the genes that react to a pathogen and find those that can enhance resistance to the disease,” she explains. “Then that gene can be incorporated into varieties using a genetic modification or non-GM approach, where you have a tag for that gene and you follow [it] through a breeding programme.”
The strategy has already turned up several genes of interest, including a sequence in wheat that seems to be linked to cold tolerance and disease resistance. “We have been characterising the [biochemical] pathway that links with the gene, so we know what other proteins interact with it,” says Doohan. “And we now have markers where we could say to a breeding company that this is a good gene to select for.”
Putting bugs to good use
As well as beefing up the genetic armoury of a plant against disease, Doohan is also looking at how bacteria themselves could help a crop fight off a potentially dangerous invader. “We are using bugs – Pseudomonas bacteria that aren’t harmful – to spray onto crops to control diseases,” she says, adding that field testing is to start this year on wheat and barley.
Doohan also wants to harness micro-organisms so we can get even more out of crops – and she’s particularly interested in their plant-busting talents.
“We know that some pathogens are very good at breaking down plants – they burst their way in so they must be good at breaking down material,” she says. “So we were wondering if you could apply a pathogen to straw and get it to break the plant material down and produce bioethanol. And when we tried it, we found we could.”
She is now looking at how bacteria could also produce valuable ingredients for foods from the waste plant material, such as anti-oxidants, and how crops could be bred to be more readily broken down by these useful bugs.
“What we really want to move towards is more multi-functional crops,” says Doohan, who receives funding from several sources, including Science Foundation Ireland, the Department of Agriculture, Food and the Marine, Enterprise Ireland, and the EU Framework 7 Programme. “That means when you grow wheat you get grain from head, but then you can also extract value from the other plant parts by harnessing these pathogens for good.”
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