After crashing from 500,000 to 300,000 hectares in the past two years, Western Australia’s canola industry is moving forward again as new, locally developed varieties, which promise black leg resistance and drought tolerance, enter the commercial testing phase.

Local growers would flock to locally adapted varieties able to withstand yield punishing drought and crippling blackleg constraints to capitalise on booming prices, which this year comfortably passed $400 per tonne.

"Limited genetic diversity has made canola a real challenge for plant breeders, because it restricts the potential to build resistance against diseases such as blackleg, or improve adaptation to new environments such as Western Australia," Canola Breeders Western Australia (CBWA) Principal Research Scientist, Wallace Cowling, said.

However, research backed by the Council of Grain Grower Organisations (COGGO) in association with the Australian Research Council at the University of Western Australia (UWA) has improved canola’s genetic variability to provide new hope.

"Canola was bred from Brassica napus, or oilseed rape, which originally occurred after a rare natural hybridization between the turnip and cabbage families, to produce a specific and relatively isolated genotype," Associate Professor Cowling said.

"Like an only child, B.napus developed as an ‘agricultural orphan’ in Europe in the past 500 years, with few close natural donors to receive disease resistances from."

To compound its genetic loneliness, B.napus was refined through a narrow selection process 30-40 years ago to produce canola quality oil. Future canola breeding progress has depended on overcoming the crop’s ‘agricultural orphan’ status.

However, canola was so different from its nearest relatives that crosses generally transferred many unwanted genes from undomesticated varieties.

"B.juncea (Indian mustard), with excellent blackleg resistance and heartiness in dry conditions, offered the greatest promise to canola breeders. But to return canola oil quality to a B.napus/B.juncea cross plant, further backcrossing back to the B.napus plant were needed. This diluted out the B. juncea qualities sought for improving canola," Associate Professor Cowling explained.

"As a result, little use has been made of the valuable Indian mustard species in improving B. napus canola."

In a recent development, B.juncea was bred for canola quality oil and so the COGGO supported project revisited the B.juncea/B.napus cross using the newly developed B.juncea as the pollen donor.

UWA researcher, Dr Janet Wroth, and PhD student, Chris Schelfhout, have monitored these crosses and selected for better seed qualities. In field trials at Merredin and Shenton Park Research Station, they tested for oil quality, drought tolerance and pod shatter and blackleg resistance.

These crosses have unleashed huge genetic variation for blackleg resistance and adaptation to drought, while some of the descendants have larger seeds and higher seed oil and protein content than current commercial canola varieties. Significantly, most of the progeny were canola-quality, which goes a long way towards overcoming the agricultural orphan status of today’s canola.