Impacts and movement of herbicide resistance genes across the Australian landscape

Weeds are one of the greatest constraints to world agriculture’s attempt to produce more food in a limited space.  Modern mechanized agricultural systems are essentially dependent on herbicides to effectively destroy weeds across large cultivated areas.  However, weeds have rapidly evolved resistance to synthetic herbicides.  Herbicide resistance has continued to appear and spread under global herbicide selection and it is a major limiting factor to food security in global agriculture.

It is mandatory to better understand the dynamics of herbicide resistance selection and the movement of resistance genes to delay the evolution of herbicide resistance in weeds.  It is generally considered that herbicide resistance is an issue to be managed on-farm, rather than at the broader landscape level.  However, a key management question is whether resistance alleles migrate into susceptible weed populations at a rate greater than they arise via de novo mutations.

Wild radish is a major weed in the Australian cropping system and yet there is no information on how and whether herbicide resistance can move in the agricultural landscape between field populations. As part of the Australian Herbicide Resistance Initiative (AHRI) Professor Busi has designed experiments to quantify pollen-mediated gene flow to monitor the spread of rare resistance traits (i.e. glyphosate resistance in wild radish).  They have also monitored the population demographics and fitness of transgenic canola volunteers growing in agricultural, semi-natural and natural environments to define dynamics and behaviour of transgenes once they escape.