ARS | Publication request: Evaluation of Soybean Cultivars for Resistance to Phomopsis longicolla

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 4, 2009
Publication Date: August 1, 2009
Citation: Li, S., Boykin, D.L., Sciumbato, G., Wrather, A., Shannon, G., Sleper, D. 2009. Evaluation of Soybean Cultivars for Resistance to Phomopsis longicolla. Phytopathology. 99(5):S72

Technical Abstract: Phomopsis longicolla is the primarily cause of soybean Phomopsis seed decay (PSD). To identify soybean lines resistant to this pathogen, 50 soybean cultivars were selected based on the recommendation by Mississippi State University (MSU) Variety Test Program in 2007. Two lines that were previously reported to be resistant in Missouri also were included. Susceptible cultivars, Hill and Williams 82 were used as checks. A field experiment was conducted using a randomized complete block design with four replications at Stoneville, Mississippi in May 2007. Plants were inoculated at the R5 stage with a spore suspension prepared from a combination of 10 isolates of P. longicolla collected from Mississippi. The seeds of soybean lines obtained from MSU without inoculation were generally healthy. Of 50 lines tested, six lines had 100% germination, 30 lines had germination rates with range from 80% to 97%, and 12 lines ranged from 63 to 77%. Only two lines had germination rates of 50% and 53%, respectively. In the seed plating assay, 37 lines had no P. longicolla infected seed, 10 and three lines had P. longicolla incidence of 3% and 7%, respectively. However, incidence of P. longicolla in seeds from inoculated field plots differed significantly (P = 0.05) ranging from 6% to 50% among soybean lines. Several lines with low disease incidence were identified. These lines will be confirmed for resistance in 2009 field trials. Collaborative research between USDA and university scientists on germplasm screening is underway to identify resistance sources to soybean PSD.