Oral Presentation Science Protecting Plant Health 2017

Alternative hosts, seed transmissibility and persistent-propagative replication of Soybean blotchy mosaic virus. (3941)

Elrea Strydom 1 2 , Gerhard Pietersen 1 2 3
  1. Microbiology and Plant Pathology, University of Pretoria, Pretoria, Gauteng, South Africa
  2. Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, Gauteng, South Africa
  3. Plant Protection Research Institute, Agricultural Research Council, Pretoria, Gauteng, South Africa

Soybean blotchy mosaic virus (SbBMV) infection of soybean results in an economically-important disease of soybean characterized by distinct blotchy mosaic symptoms. Soybean blotchy mosaic virus, a member of the genus Cytorhabdovirus, has only been reported in South Africa and re-emerges in the warmer, low-lying soybean production areas early in each new season. In this study, mechanisms by which the disease may persist between soybean growing seasons, such as the presence of alternative plant hosts, seed transmissibility and replication in its leafhopper vector Peragallia caboverdensis was investigated. Weeds, trees and crops in close proximity to soybean fields with high soybean blotchy mosaic disease incidences were collected and tested for the presence of the virus by RT-PCR. Three putative alternative hosts of SbBMV were identified, which included two herbaceous weeds, Lamium amplexicaule and Flaveria bidentis and a perennial tree species, Gymnosporia buxifolia, which may serve as over-wintering hosts for SbBMV. Seed transmissibility was assayed by collecting seed from PCR tested, infected soybean mother plants, and growing them in insect-free greenhouses. A total of 2, 829 seedlings representing four commercial cultivars were evaluated, and it was concluded that SbBMV was not seed transmissible at incidences detectable in the number of seedlings tested. Lastly, replication of SbBMV in its vector Peragallia caboverdensis was investigated using a positive strand-specific RT-PCR directed against the replicative intermediate of SbBMV. This was demonstrated through detection of the positive strand of SbBMV. Future control strategies of the virus should focus on management of alternative hosts and the insect vector, as these function as SbBMV reservoirs during the winter months.