Adelaide scientists have identified the major gene responsible for
boron toxicity tolerance in barley, allowing breeders to select with 100 per
cent accuracy barley varieties that are tolerant to boron. The findings were
published on 30 November 2007 in the journal Science.
The discovery was made by a research team led by Dr Tim Sutton of the
Australian Centre for Plant Functional Genomics at the University of
Adelaide's School of Agriculture, Food and Wine at the Waite Campus.

The gene, known as Bot1, was first discovered in a boron-tolerant
African barley known as Sahara.

Bot1 helps barley plants survive in soils containing high amounts of
boron, common to much of Southern Australia, Asia and Africa. The gene works
by preventing the entry and accumulation of boron in the plant, which causes
the damage and limits growth.

Since the early 1980s scientists have known about the toxic effects of
boron on cereal crops in southern Australia.

"Highly boron-tolerant barley landraces (crop varieties) had been
previously identified, but nothing was known about the molecular basis of
their tolerance," says Dr Sutton. `We used genomics, which is a combination
of modern molecular biology techniques, to identify the sequence of the
boron-tolerant gene from Sahara, and the underlying molecular mechanism that
provides the tolerance."

"Boron is an essential micronutrient for plants but they require just
the right amount, and boron toxicity and deficiency severely limit crop
production worldwide," says Professor Peter Langridge, CEO of the Australian
Centre for Plant Functional Genomics. "This discovery means that farmers
growing barley in high boron environments will be able to choose varieties
of barley more suited to their soils, therefore minimising crop loss to this
condition."

Scientists can now work towards transferring this gene into
commercially important barley varieties using either conventional breeding
or transformation techniques.

Boron toxicity appears in the tips of the older leaves first, turning
them yellow with characteristic brown spots. It then extends down the leaf
as toxicity increases until it causes tissue death and eventually plant
death.

Barley is a main ingredient in the production of beer and
confectionary. In Australian barley crops, yield has been estimated to be
reduced as much as 17 per cent as a result of boron toxicity.

Thirty per cent of South Australia's grain growing soils are affected
by high levels of boron.

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