From	Gene Flow a Canola Headache By Kim Woods 22 March 2002

Canola growers may be in for some genetically modified headaches over outcrossing, or gene flow between plants. 

A study into the gene transfer between herbicide tolerant and susceptible canola crops by Co-operative Research Centre for Australian Weed Management has revealed canola will outcross, meaning genes will move from crop to crop. 

An Adelaide University senior lecturer in weed management, Dr Chris Preston, said the likelihood of gene flow was low and was a management issue for canola growers. "But it is going to happen, and we've got to expect it to happen," Dr Preston said. 

"Gene contamination can come from many sources -- seed contamination, animals or wind can blow canola across (paddocks)." 

CRC researchers evaluated the implications of a 1 per cent gene flow between canola crops. 

Material was used from herbicide-resistant canola crops grown in the Wimmera, Mallee and Riverina regions. 

A total of 48 million seedlings were screened for gene transfer frequency under the project. 

"One collection had frequencies of 0.05 per cent to 0.07 per cent. The bottom line in a field situation is that's pretty low," Dr Preston said. 

"If we are looking at a 1 per cent cut-off level, it means a farmer can grow a genetically engineered crop next door to another farmer growing a non-GE crop, and it won't affect the ability to market that crop." 

At the Victorian sites, outcrossing of resistant genes occurred up to 2km from the source. 

Dr Preston said no resistant genes were detected greater than 3km. 

"There were low levels of gene flow detected -- we've got to expect that to happen," he said. 

"There is not a simple decline with distance, it is influenced by a whole range of other things." 

Although no clear patterns were established between bee activity and gene transfer, researchers believe bees play a major role. 

"We believe most of the gene movement is bee mediated because even if the crops were grown right together, they showed little or no gene flow," Dr Preston said. 

"If it was wind, we would expect to see quite a significant level of gene flow. 

"Our work says you need a buffer of more than 3km but there can be zero (gene flow) for crops right next door." 

Dr Preston said the control of crop volunteers was important in managing herbicide tolerant crops. 

"Contamination of current crops with volunteers from a previous canola crop may become a major management headache," he said.

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