Posted June 22, 2005, ARS
News Service: The first soybean line with genetic resistance
to charcoal rot has been released by Agricultural Research Service
scientists in Mississippi.
Charcoal rot, caused by the soilborne fungus Macrophomina phaseolina,
is a major yield-limiting disease of the Mid-South and other soybean-producing
regions throughout the world.
The new line, DT97-4290, developed by scientists in the ARS Crop
Genetics and Production Research Unit at Stoneville, is a potentially
valuable source of resistance to charcoal rot for soybean breeders
and producers in areas experiencing yield losses due to the disease.
Charcoal rot symptoms usually appear when weather conditions are
hot and dry, causing the soybean plant to lose vigor. In more advanced
stages, petioles and leaves may turn yellow and wilt, while remaining
attached to the plant. No chemical controls currently exist for
charcoal rot, and resistance has been hard to identify.
Field studies were conducted at Stoneville to find charcoal rot
resistance among 24 selected soybean genotypes. The researchers
identified three breeding lines with genetic resistance, according
to Bob Paris, the research geneticist who developed the line with
Alemu Mengistu, a soybean pathologist.
The new line was selected for its adaptation to the clay soils
of the lower Mississippi River valley, and for its field resistance
to charcoal rot, soybean mosaic virus and stem canker, and moderate
resistance to frogeye leafspot.
Genetic material of this release will be deposited in the National
Plant Germplasm System, where it will be available for soybean researchers