Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2006
Publication Date: July 1, 2006
Citation: Li, S., Hartman, G.L. 2006. Pathogenic and Molecular Characterization of Phomoposis longicolla, the Fungus that Causes Soybean Seed Decay. Phytopathology. 96:S68. Technical Abstract: Phomopsis seed decay of soybean is a major cause of poor quality of soybean seeds in the United States, especially in the mid-southern USA. The disease is caused primarily by the fungal pathogen, Phomopsis longicolla. To compare differences among isolates, 30 isolates from soybean and other hosts were characterized using pathogenic and molecular approaches. Pathogenicity tests were performed in the greenhouse using a cut-stem method with culture-plug inoculation on 2-week old soybean seedlings of susceptible line Williams 82. All isolates caused stem lesions. There were significant differences among isolates based on stem lesion length as a percentage of the stem length (P less than or equal to 0.05). Isolate PL1 from Illinois was the most aggressive isolate among 18 soybean isolates. Cluster analysis indicated that there were three groups of isolates based on stem lesion length. The growth diameter of isolates on potato dextrose agar was not correlated with stem lesion length. In addition, 12 isolates from other hosts caused stem lesions on soybean, ranging from 14 to 85 percent of the total stem length. Preliminary Inter Simple Sequence Repeat(ISSR) analyses indicated that most of soybean isolates from the same geographic origin had similar banding patterns although polymorphic bands were found using the primer ISSR004.