Specific effects of soybean mosaic virus on total nitrogen ureide nitrogen and symbiotic nitrogen fixation activity in glycine max and glycine soja
Orellana, R.G.; Reynolds, S.L.; Sloger, C.; Van Berkum, P.
Phytopathology 73(8): 1156-1160
ISSN/ISBN: 0031-949X Accession: 006456403
Plants of cultivated soybeans (G. max 'Hill' and 'Essex') and 2 introductions of wild annual soybean, G. soja PI [plant introduction] 424-005 and PI 378-693-B, were studied in the greenhouse for their response to soybean mosaic virus. Significant decreases in top and nodule weights had occurred after 53 days in plants inoculated in the primary leaf stage with the Beltsville isolate of soybean mosaic virus (SMV-B). Plants of G. soja infected with SMV-B had significantly higher total N and ureide-N contents than the controls. Plants of G. max 'Hill' showed no significant differences for these 2 parameters, while total N increased significantly in infected plants of 'Essex'. N2 fixation activity, measured by the acetylene reduction assay, decreased significantly in all genotypes except 'Hill'. Measurements of nodule-specific nitrogenase activity indicated that nodules from plants infected with SMV-B of 'Hill' and PI 378-693-B fixed N2 at rates exceeding those of the uninoculated controls. The presence of SMV-B was detected by ELISA [enzyme-linked immunosorbent assay] in inoculated plants at harvest. Leaves developed higher virus concentrations than did nodules, and there was no correlation between foliar virus titer and symptom severity ratings. Symptoms were most severe on G. soja PI 424-005, less severe on G. max 'Essex' and G. soja PI 378-693-B, and least severe on G. max 'Hill'.