Western Australia
August 22, 2007
Western Australian researchers are
providing solutions for greater control of necrotrophic fungal
pathogen resistance in legumes to help reduce chronically high
legume crop losses attributed to recalcitrant fungal diseases.
 As
part of a recent Grains
Research and Development Corporation (GRDC) Board visit to
Western Australia, GRDC supported
CSIRO post-doctoral fellows, Dr Jonathan Anderson and Dr
Judith Lichtenzveig, presented genetic legume research they hope
to use in plant breeding programs.
Dr Anderson (photo, right) has made an important breakthrough
into understanding how plants resist infection by Rhizoctonia
solani, the fungus causing root and crown rot in legumes and
bare patch in cereals.
“R. solani is widespread, infecting a broad range of crops, but
because there are no acute lesions on leaves, growers may not
immediately recognise it as a problem,” he said.
“However, the root disease continually drags down production and
can be particularly severe after drought when large amounts of
dead plant material remains in the soil and antagonistic soil
microbes decline.”
Breeding plants with complete R. solani resistance has not been
possible due to the complex genetics involved in the plant’s
response to the disease.
Dr Anderson identified partial resistance to R. solani in a line
of the model legume Medicago truncatula and has identified a
mutant highly susceptible to the disease.
“Subsequent work identified genes involved in the partial
resistance and increasing the activity of one of these genes
increased tolerance to the disease,” he said.
“Research into how best to use these genes to increase root and
crown rot resistance in a range of legumes is ongoing and this
approach to fighting disease could result in stable resistance
and long term benefits for growers,” Dr Anderson said.
 Dr
Lichtenzveig (photo, right) demonstrated the value of Medicago
as a model crop for legumes, identifying three genomic regions
involved in Medicago resistance to the devastating Fusarium wilt
disease, which affects a large number of legume crops, including
fababean, pea, lentil and chickpea.
“Isolating the genes underlying these regions is a precursor to
evaluating them in other legume crops,” she said.
“The genetic relationship between the model species and other
legumes assists molecular marker development and accelerated
crop development.”
GRDC Western Panel member and Director of the Australian Centre
for Necrotrophic Fungal Pathogens at Murdoch University,
Professor Richard Oliver said without Medicago only a small
fraction of genetic maps would be available in legumes.
“We can use Medicago genetic maps to develop genetic maps in
legume species due to the striking similarity between them,” he
said.
“Identifying the genetic basis for disease resistance in
Medicago by isolating susceptible and resistant Medicago
cultivars can improve disease resistance in related legumes and
restore grower confidence in legumes,” Professor Oliver said. |
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