Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2000
Publication Date: N/A
Technical Abstract: Barley Yellow Dwarf (BYD), the most economically important virus disease of cereal crops, is caused by 6 related luteoviruses that share a common circulative transmission pathway through aphid vectors. An understanding of the vectoring process may lead to effective disease control strategies. We are taking advantage of the genetic diversity, reproductive strategy, and the differential ability of Schizaphis graminum biotypes to transmit the BYD viruses to unravel the molecular and cellular mechanisms of circulative plant virus-insect vector interactions. Five of 9 biotypes of S. graminum efficiently transmit multiple BYD viruses, but differ in which viruses they transmit. Four biotypes transmit the viruses inefficiently or not at all. Plant host adaptation is correlated with virus transmission efficiency in 7 of 9 biotypes; however, it is not a factor that regulates virus transmission. The barriers to transmission are related to the uptake eor release of virus from the salivary glands. In all virus-aphid combinations examined, virus was acquired by the insect and moved from the gut into the hemocoel. Interestingly, the vector competence is developmentally regulated for some but not all viruses. Virus that is acquired by 1st and 2nd instar vectors is efficiently retained and transmitted throughout the life of the insect. Virus acquired by older instars or adults is retained in the hemocoel, but not released via the salivary system. Aphid populations differing in vector competence have been induced to produce sexual forms and mated. The inheritance and underlying molecular genetics of circulative transmission can now be examined in progeny maintained as clonal lines via parthenogenetic reproduction.