Adelaide, South Autralia
November 30, 2007
 Adelaide
scientists have identified the major gene responsible for boron
toxicity tolerance in barley, allowing breeders to select with
100% accuracy barley varieties that are tolerant to boron. The
findings have today been published in the journal, Science.
The discovery was made by a research team led by Dr Tim Sutton
(photo) 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.
The paper, Boron toxicity tolerance in barley arising from
efflux transporter amplification (2007) by Tim Sutton, Ute
Baumann, Julie Hayes, Nicholas C. Collins, Bu-Jun Shi, Thorsten
Schnurbusch, Alison Hay, Gwenda Mayo, Margaret Pallotta, Mark
Tester and Peter Langridge, appears in the 30 November issue of
Science.
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% as a result of boron
toxicity.
Thirty per cent of South Australia's grain growing soils are
affected by high levels of boron.
|
|
