VIEW ARTICLE

Physiology and Biochemistry

Enhancement by Soybean Mosaic Virus of Bean Pod Mottle Virus Titer in Doubly Infected Soybean. L. A. Calvert, Graduate assistant, Department of Plant Pathology, University of Kentucky, Lexington 40546-0091, Present address of senior author: Institute of Food and Agricultural Science, Agricultural Research and Education Center, Lake Alfred, FL 33850; S. A. Ghabrial, associate professor, Department of Plant Pathology, University of Kentucky, Lexington 40546-0091. Phytopathology 73:992-997. Accepted for publication 28 January 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-992.

The concentration of bean pod mottle virus (BPMV) in soybean plants doubly infected with BPMV and soybean mosaic virus (SMV) was significantly higher than that in singly infected plants. The enhancement of BPMV titer in doubly infected plants was evident in both greenhouse and field-grown plants and was independent of the virus assay method used. The enhancement phenomenon was detected in doubly infected plants regardless of the timing, sequence, or means of inoculation with the two viruses. No significant differences in SMV concentration were detected between singly and doubly infected plants. The BPMV titer in singly infected plants, as determined by enzyme-linked immunosorbent assay (ELISA), varied with leaf position and could be correlated with symptom severity. In doubly infected plants, however, the variation in BPMV titer with leaf position was less pronounced. Although the BPMV titer, as determined by ELISA, remained relatively constant in the individual fully expanded trifoliolate leaves of singly and doubly infected plants, a decline in infectivity with age of infection was detected by local lesion assays. The yields of field-grown doubly infected plants of two soybean cultivars were significantly lower than that of plants singly inoculated with either SMV or BPMV.