|Hein, Gary - UNIVERSITY OF NEBRASKA|
|Morris, T. - UNIVERSITY OF NEBRASKA|
Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2001
Publication Date: July 21, 2001
Citation: Hall, J.S., French, R.C., Hein, G.L., Morris, T.J., Stenger, D.C. 2001. Cross-protection, subdivision within plant tissues, and vector transmission bottlenecks as mechanisms of genetic isolation in wheat streak mosaic virus. American Society For Virology Meeting.(Not published by meeting) Technical Abstract: Field populations of wheat streak mosaic virus (WSMV) contain a complex array of closely related genotypes, yet mixed infections are uncommon. Cross-protection and vector transmission bottlenecks have been proposed as genetic isolating mechanisms. Molecular markers were used to monitor establishment and resolution of mixed infections with strains of WSMV. Two closely related strains from the US (Type and Sidney 81) exhibited reciprocal cross-protection, confirming this classic phenomenon as a mechanism of genetic isolation. In contrast, cross-protection between the US strains and the divergent El Batan 3 strain from Mexico was unilateral, erratic, and only partially effective. Distribution of WSMV strains within individual leaves of plants supporting mixed infections of Type and Sidney 81 was spatially non-uniform. Strain distribution among individual tillers of coinfected plants also was heterogeneous, with some containing either Type or Sidney 81 alone and some containing both strains. No subdivision was observed within tissues of plants coinfected with Sidney 81 and brome mosaic virus. These results suggest that spatial subdivision of closely related viruses within a coinfected plant operates via cross-protection at the cellular level. Transmission by individual wheat curl mites, acquiring virus from coinfected source plants, often resulted in test plants bearing only a single WSMV strain. Spatial subdivision of virus strains within coinfected source plants likely contributed to vector transmission bottlenecks during acquisition. Collectively, these three distinct mechanisms enhance genetic isolation of individual viral lineages, and together with stochastic processes, may explain generation and maintenance of diversity in WSMV field populations.