LINDELL BEACH, B.C. — Pre-harvest sprouting can deal wheat farmers a major financial blow.
The problem is so big that the world’s farmers are estimated to lose as much as $1 billion a year because of it, according to numbers released by McGill University in Montreal.
It reduces yield and end-use quality and affects the viability of the seed for next year’s planting, according to a recent report that McGill University scientists published in the journal PLOS ONE.
That report also estimated that the Canadian wheat industry loses $100 million a year to pre-harvest sprouting.
Read Also
August rain welcome, but offered limited relief
Increased precipitation in August aids farmers prior to harvest in southern prairies of Canada.
The problem is caused when too much rain and humidity triggers certain wheat varieties to germinate before the crop is ready for harvest.
Now the McGill team has discovered that pre-harvest sprouting may be driven by more than genetics and could be influenced by a combination of genetic and epigenetic influences.
“Epigenetics is a personality of a gene,” said Jaswinder Singh, assistant professor in McGill’s plant science department and leader of the re-search team.
“To explain, my name is Jaswinder and I wear a turban. Sometimes I wear a blue turban and sometimes I wear a red turban. My turban may change with colour but I am still Jaswinder,” he said.
“It’s the same way when we are talking about genetics. A gene may be a red colour or a gene may be a blue colour, but the gene is still the same. In the case of epigenetics, the personality of the gene will change but the gene will not be different. That means that it may be expressed differently. It’s the same gene and same nucleotide, but it will behave differently.”
The team studied plants from 10 wheat varieties with varying degrees of seed dormancy:
- Snowbird, RL4137, AC Domain, AC Karma, SC8021-V2, Thatcher, and AC Vista are pre-harvest sprouting resistant or tolerant varieties.
- AC Andrew and Sadash are susceptible to pre-harvest sprouting.
- The CDC Teal variety is medium pre-harvest sprouting reactive.
- The Chinese Spring variety is used as a model for genetic mapping purposes.
The varieties were put in a growth chamber at 20 C under a 16 hour light-eight hour dark cycle.
Singh’s team discovered that a key gene acted like a control switch to govern how a plant would respond to rain and high humidity.
“In pre-harvest sprouting, we agree with other researchers that genes are involved … but something is controlling them, so we thought that this control is by epigenetics,” he said.
“There are genes which are actually changing the expression of those genes on the main switch which controls (pre-harvest sprouting). That’s why this discovery has become unique.”
The switch Singh is referring to is in a key gene known as ARGONAUTE4_9 in a complex pathway known as RNA dependent DNA Methylation. The pathway is made up of several proteins that influence growth, development and stress signals.
“This is a pathway by which, in the genome, genes are controlled,” said Singh. “That pathway has many different genes involved, which work together so that they can change the expression of other genes.”
Singh said the plant can sense an environment where there is high humidity or low humidity, which triggers a response to express or not express an action to environmental triggers.
“If it can change all the expressions of genes made in relation to the environment or the surrounding climate, then I can think of the pathway playing a role just like a brain,” said Singh.
Once the specific genes were identified, the researchers compared the way they were expressed in pre-harvest sprouting resistant wheat to susceptible wheat.
Singh is confident that, with the new understanding from the research, breeders will be able to select for greater pre-harvest sprouting resistant wheat varieties. The discovery has also proved important for other cereals, such as barley.
