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ARS Home » Midwest Area » Urbana, Illinois » Soybean/maize Germplasm, Pathology, and Genetics Research » Research » Publications at this Location » Publication #77872
Title: THE EFFECT OF RBS2 ON YIELD OF SOYBEAN

Author
item BACHMAN, MICHAEL - UNIV OF ILLINOIS
item NICKELL, CECIL - UNIV OF ILLINOIS
item STEPHENS, P - PIONEER HI-BRED INT./IL
item NICKELL, A - ASGROW SEED CO/WISCONSIN
item Gray, Lynn

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Brown stem rot is an important soybean disease in the north central United States. This soybean disease is caused by the fungus called Phialophora gregata. A plant gene called Rbs2 has been found in a soybean plant that makes the plants with this gene resistant to the fungal pathogen. The objective of the present study was to determine if different plants containing the Rbs2 gene yielded more than plants without this gene. In 1994, 5 different plant types containing the Rbs2 gene were compared to plants without this gene for yield and amount of disease at six locations in Illinois and in 1995 the same plant types were compared at nine different locations in Illinois. Based on the results from this two year study, it was found that where there was more than 13 percent of the susceptible plants showing the disease, the plants with the Rbs2 gene yielded 10 percent more than the susceptible plants. This study has supplied new information about the yield advantage of plants with a known gene for resistance to soybean brown stem rot. This information should be useful to soybean plant pathologists and soybean geneticists. Both public and private soybean seed producers can use the different soybean plants containing the Rbs2 gene as a source to develop new resistant plants.

Technical Abstract: Brown stem rot, caused by Phialophora gregata, is a vascular/foliar soybean disease of the north central United States. Although yield comparisons have been made between susceptible and resistant lines, no study has evaluated yield differences between near-isogenic lines differing in brown stem rot reaction. The objective of this study was to compare brown stem rot resistance and brown stem rot susceptible near-isogenic lines for yield and other agronomic traits. In this study, five pairs of near-isogenic lines for the Rbs2 resistance gene were grown at six locations in Illinois in 1994 and nine locations in Illinois in 1995, relying on natural infection with P. gregata. Near-isogenic lines were evaluated for disease incidence (percentage of plants exhibiting brown stem rot foliar symptoms) and disease severity (degree of foliar chlorosis/necrosis) in late August and harvested in September and October. At seven locations with 13% or greater incidence of brown stem rot, a yield advantage was associated with the resistance gene, Rbs2. At eight locations with less than 3% incidence of brown stem rot there was no yield difference between resistant and susceptible near-isogenic lines. These results indicate that Rbs2 prevents yield loss in the presence of brown stem rot.