Eco-tilling detects resistance

More than 305 types of weed in more than 50 countries have been reported to be resistant to at least one herbicide, and an increasing number of weeds owe their success to their genetic diversity.

Scientists say techniques are needed to detect mutations when they first occur, so farmers can test for herbicide resistance in the field and manage weeds accordingly.

NSW Department of Primary Industries (DPI) molecular biologist,Dr Mui-Keng Tan, together with a team of researchers from Japan, investigated a technique called ecotilling and found it offers a quick, cheap and reliable means of detecting early signs of herbicide resistance in weeds.

Unlike the traditional molecular approach, eco-tilling uses reverse genetics. Genes are not fully sequenced; instead, mutations in single molecules that make up genes are identified purely on the basis of their position in the genome.

Dr Tan said new mutations can be detected and known ones can be screened for a fraction of the cost of alternative genetic methods.

This makes it a powerful, low cost and high throughput alternative to full sequencing.

Dr Tan has been investigating the technique with Dr Guang-Xi Wang from Kyoto University, who was funded by the Grains Research and Development Corporation to collaborate with Dr Tan at DPI’s Elizabeth Macarthur Agricultural Institute at Camden.

She says the use of the eco-tilling technique to test for resistance could help farmers to manage herbicide use in crop rotations more economically and effectively.

Dr Tan’s research has focused on herbicide resistance in two oft he most significant weeds affecting Australian cropping systems -wild oats and rye grass – and to together with Dr Wang she also examined weeds in rice fields inJapan.

Dr Tan said the every weed-herbicide system is specific.

“The ecotilling technique can beapplied on any particular system, pending availability of molecular data on the target genes of theherbicides,” she said.

An article on the research in Japan was published recently in the international journal Pesticide Biochemistry and Physiology.

Contact Mui-Keng Tan, Camden, (02) 4640 6445 or mui-keng.tan@dpi.nsw.gov.au
– Joanne Finlay