Scientists from the USDA Agricultural Research Service (ARS) developed a new
technique that could boost the search for soybeans with resistance to fungus
that causes Phomopsis seed decay (PSD). The pathogen degrades soybean seed
and decreased the quality of its protein and oil. Outbreaks of PSD in 2012
in 16 U.S. states led to losses of over 2 million bushels.

The researchers used the common soil bacterium Agrobacterium tumefaciens to
transfer genes for an antibiotic marker and green fluorescent protein (GFP)
into the nucleus of the fungus' cells. This led to new strains of the fungus
that produce the protein and exhibit a green glow when exposed to light in
the blue-to-ultraviolet range.

Soybean seedlings were inoculated with the modified strains to study how the
infection occurs in the tissues of both resistant and susceptible soybean
germplasm lines. The approach should also help in identifying sources of PSD
resistance that are undetected when using conventional disease screening
methods, such as those requiring field observation of symptoms.

The study was published in the Journal of Microbiological Methods.

[www.ars.usda.gov]