Two well characterized Soybean mosaic virus strains and two Bean pod mottle virus strains were tested for their reaction when double inoculation (simultaneous or sequential) was performed on five differential Glycine genotypes. Results showed that the interaction between viruses depended on the host genotype and the timing of infection. Both synergistic and antagonistic responses were observed. A synergistic interaction gave rise to chimeric mosaic/necrosis symptoms in mosaic-responding plant genotypes simultaneously inoculated with BPMV and SMV. Also, PI 407019, an accession with resistance to SMV-G1 and G7 isolates, had significant SMV accumulation when infected with both BPMV and SMV. Moreover, when SMV was inoculated 1wk before BPMV, PI 407019 and ‘5002T' soybean exhibited severe necrosis and death. On the other hand, an antagonistic reaction was observed in the line V94-3971 when BPMV was inoculated before SMV-G7. In this case, a reduced percentage of plants expressed the expected stem tip necrosis to SMV. A similar pattern was observed in PI 96983 which showed a delay in necrotic symptom onset as well as a reduced necrosis rate when simultaneously inoculated with BPMV and SMV-G7. In conclusion, our results showed that the interaction between SMV and BPMV depended on the isolates of the viruses causing disease, the host genotype, and the timing of infection. Pre-infection with SMV triggered a response in certain genotypes that led to severe necrosis and death of the plant, and this reaction was phenotypically different from the stem tip necrosis manifested by some hosts to single inoculations with particular SMV or BPMV strains.
See more of Crops Posters/Reception
See more of The ASA Southern Regional Branch (June 19-21, 2005)