Home' Partners : Partners February 2010 Contents since resistance traits often allow wheat merely
to survive drought. Instead CSIRO looks to
improve 'water productivity', an approach
developed by Dr John Passioura, CSIRO's
renowned plant drought physiologist.
"One of the main factors limiting progress
when it comes to breeding for dry conditions
is inadequate 'phenotyping'---by which we
mean the ability to characterise plant traits with
the potential to improve water-limited yield,"
Dr Passioura says. "Almost all such phenotyping
in the laboratory relies on screening plants for
their ability to survive severe water stress, yet
better survival rarely means better production."
By focusing instead on lifting production,
over the years Dr Richards and his CSIRO
colleagues have developed phenotyping
technology that has resulted in the commercial
release of new wheat varieties capable of
remaining productive under a wide range of
"The emphasis on water productivity is
PARTNERS NOVEMBER 2009 FEBRUARY 2010
By allowing breeding programs to bypass complex and time-consuming
field trials at multiple sites and in different seasons, DNA markers
are an attractive upcoming technology and ACIAR is promoting their
development for traits that can help some of the world's poorest farmers.
Of particular interest is a trait that evolved in Africa that is likely to
relate to an extremely efficient use of water, as well as differences in
rooting. The trait was discovered in sorghum, a staple food for about 400
million people in 30 countries. Sorghum grain and straw (or stover) are
also valuable as livestock feed in dry or marginal areas, such as parts of
northern Australia and in the post-rainy season (Rabi) in India.
Dr Paul Fox, ACIAR's crop improvement and management research
program manager, says that Ethiopian sorghum lines that can fill grains
and mature even through terminal drought are of particular interest. The
tolerance is due to a trait called 'Stay Green', in which a few leaves stay
green long enough to provide the starch needed to fill grain.
"Stay Green was identified in several sorghum lines, including one
called 'pineapple t o p ', a low-yielding plant type that is not suited to
commercial cultivation," Dr Fox says. "So we have a project to use the DNA
markers of Stay Green and insert them into varieties that farmers are
commonly growing. This will allow breeders all over the world to move
Stay Green into more productive sorghum varieties."
The project is being undertaken in a partnership between India
and Australia headed by Dr Vincent Vadez and Dr Tom Hash from the
International Crops Research Institute for the Semi-Arid Tropics, in
India. Participating from Australia are the University of Queensland and
Queensland Primary Industries and Fisheries, which are working with
India's National Research Centre for Sorghum and the International
Livestock Research Institute.
Field activities started in India during the 2008--09 Rabi and will
continue through to 2012, involving the Queensland researchers who are
working on predicting the possible effects of Stay Green on yield across
environments using crop simulation modelling.
The researchers know that Stay Green is a complex trait involving
many genes, gene interactions and gene-by-environment effects.
Cracking the molecular and physiological basis of a major drought-
tolerance trait stands to deliver potentially enormous benefits in the long
run, and not just for sorghum breeders.
"If we understand a drought-tolerant trait like Stay Green in sorghum,
then the potential exists to use those genes and markers, and their
related mechanisms, in other major food crops such as rice, wheat or
maize, and that could have huge impacts on food security," Dr Fox says.
'Stay Green' on the mark
PROJECT: CIM/2007/120: Improving post-rainy
sorghum varieties to meet growing grain and
fodder demand in India
CONTACT: Dr Paul Fox, email@example.com
PROJECT: CIM/2006/071: Indo--Australian project
on root and establishment traits for greater
water-use efficiency in wheat
CONTACT: Dr Michelle Watt, firstname.lastname@example.org
(Opposite page) Visiting a CSIRO field site to look at wheat establishment and root vigour are Dr Satish Misra (left) of the Agharkar Research Institute and Dr G.P. Singh (right) of the
Indian Agricultural Research Institute. They were shown around by CSIRO's Michelle Watt (second from left) and Dr Richard Richards (second from right).
important because it opens three avenues for
pre-breeders to identify better-performing
wheat germplasm," Dr Richards says. "We can
look for traits that improve the amount of water
the crop captures, or the efficiency with which
the crop uses the water, or the partitioning of
growth into grain (the harvest index). If you can
improve any one of those three then you will
improve yield under drought."
To date, phenotyping technology developed
at CSIRO Plant Industry has primarily targeted
above-ground plant features. However,
researchers know that root traits also stand to
drive water-productivity gains, and the project
finally shifts water productivity phenotyping
Impressive gains are thought to be possible
by selecting for deeper roots at around the time
of flowering and seed-setting. Dr Watt says that
any water taken up about this time is directly
used for grain production. "We have calculated
that the uptake of an extra 10 millimetres can
contribute to an extra half a tonne of grain per
hectare," she says. "So the deep-root trait has
very high water productivity: a high conversion
of water into yield."
Root length in mature plants, however, is
extremely difficult to measure, especially when
comparing water productivity in hundreds of
wheat lines. It requires field plantings in real
cropping zones and coring of the soil to a
depth of two metres to physically measure the
root system. Yet that is precisely what the Indian
researchers are doing: coring at the ideal trial
sites to find out how deep the roots penetrate
in a wide range of elite wheat varieties, Indian
Dr Paul Fox, ACIAR's
research program manager
for crop improvement.
PHOTO: EVAN COLLIS
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