Madison, Wisconsin
July 17, 2007
Across the southern United States,
an invisible, yet deadly parasite known as the root-knot
nematode is crippling soybean crops. While plant breeders are
racing to develop cultivars resistant to the root-knot nematode,
they are being slowed down by current time-consuming and
expensive methods of screening for resistant plants. Now,
researchers believe they have found a shortcut for screening
resistant soybean crops.
Researchers at the University of
Georgia report the discovery of several molecular markers
that will help soybean breeders to accurately screen for
root-knot resistant plants at a fraction of the time and cost of
current screening techniques in the July issue of
The Plant Genome.
While previous studies of soybean crops helped researchers to
locate genes associated with root-knot nematode resistance,
University of Georgia scientists recently identified single
nucleotide polymorphisms (SNPs), slight variations in the DNA,
nearby genetic regions that code root-knot nematode resistance.
After linking the identified SNPs to root-knot nematode
resistance, scientists developed a marker assisted screening
test that used SNPs to determine whether or not plants were
resistant to root-knot nematode.
“The basic objective of any breeding scheme is to identify elite
individuals that can pass on their desirable characteristics,”
explained Bo-Keun Ha, lead author of study. While Ha says most
conventional breeders rely on phenotypic evaluations of plants
to select the plant with most desirable traits, this process
takes time and money. For example, if a breeder wants to select
plants with resistance to root-knot nematode based upon a
phenotypic evaluation alone, he or she must grow a large
population of plants, inoculate plants with nematode eggs, wait
until the growth of the nematode and evaluate the damage before
selecting the most resistant plants.
Instead of relying on the time-consuming phenotypic screening to
determine whether or not the root-knot resistance genes are
present in soybean crops, “marker assisted selection can inform
breeders about the presence of the resistance gene in individual
plants,” said Ha. Also, because marker assisted selection
involves the screening of a few markers across thousands of
plants Ha pointed out that the marker assisted selection is
rather inexpensive and time efficient.
“Our results found SNPs linked to two root-knot nematode
resistance genes and developed the resources for a relatively
high throughput method of selection for the two genes,” said Ha.
“The SNP assays that we have reported will empower soybean
breeders to efficiently incorporate root-knot resistance genes
into new productive cultivars.”
The Plant Genome
is a peer-reviewed, international journal of applied plant
genomics research published four times a year by the Crop
Science Society of America.
The American Society of
Agronomy (ASA), the
Crop Science Society of America (CSSA) and
the Soil Science Society of
America (SSSA) are educational organizations helping their
10,000+ members advance the disciplines and practices of
agronomy, crop and soil sciences by supporting professional
growth and science policy initiatives, and by providing quality,
research-based publications and a variety of member services. |
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