By Joanne Finlay
A new molecular tool developedby Australian and Japanese researchers
is expected to help farmers address what has become one of the major threats
to conventional agricultural practices - herbicide 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.


[www.checkbiotech.org]