Submitted to: Soybean Research World Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: April 4, 2009
Publication Date: August 10, 2009
Citation: Li, S., Chen, P., Hartman, G.L., Smith, J.R., Nelson, R.L. 2009. Research Highlights on Soybean Phomopsis Seed Decay in the U.S: Pathogen Characterization, Germplasm Screening, and Genetic Resistance. Soybean Research World Conference Proceedings. P199:91-92 Technical Abstract: Soybean Phomopsis seed decay (PSD), caused by Phomopsis longicolla, is the major cause of poor seed quality in the United States. Forty-seven isolates were characterized using pathogenic and molecular approaches. There were significant differences among isolates based on stem lesion length as a percentage of the stem length. Preliminary inter simple sequence repeat (ISSR) analyses indicated that most isolates from the same geographic origin had similar banding patterns although polymorphic bands were found. To identify soybean accessions with resistance to PSD, 208 maturity group V plant introductions not previously tested for resistance to PSD were selected and grown in Mississippi in 2007. Fourteen accessions with low incidence of P. longicolla and high germination rate were selected based on the seed plating assay. A replicated field experiment was conducted in 2008. Plants were inoculated at the R5 stage with P. longicolla spore suspension. Several lines were identified with low disease incidence and good seed quality. Genetic resistance to PSD has been reported in over 25 plant introductions, among which PI 417479, PI 360841, and PI 80837 were studied for inheritance. MO/PSD-0259 carries a single dominant gene for PSD resistance derived from PI 417479 whereas resistance in PI 80837 is conferred by a different gene. Recent studies showed that PI 360841 carries two complementary dominant genes for PSD resistance; both are different from the gene in MO/PSD-0259 but one of them is the same as the gene in PI 80837. Molecular markers were identified for the genes in PI 80837 and MO/PSD-0259.