|VAN ECK, LEON - Colorado State University|
|SCHULTZ, THIA - University Of Pretoria|
|LEACH, JAN - Colorado State University|
|Scofield, Steven - Steve|
|PEAIRS, FRANK - Colorado State University|
|BOTHA, ANNA-MARIA - University Of Pretoria|
|LAPITAN, NORA L. - Colorado State University|
Submitted to: Plant Biotechnology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2010
Publication Date: 10/1/2010
Citation: Van Eck, L., Schultz, T., Leach, J.E., Scofield, S.R., Peairs, F.B., Botha, A., Lapitan, N.V. 2010. Virus-induced gene silencing of WRKY53 and an inducible phenylalanine ammonia-lyase in wheat reduces aphid resistance. Plant Biotechnology Journal. 9:1023-1032.
Interpretive Summary: Wheat production in the western United States can be significantly limited by damage from the Russian Wheat Aphid (RWA). Fortunately, genetic resistance to RWA has been identified, but little is known about its mechanism. Previous research has identified changes in gene expression that occur in wheat plants that are resistant to RWA. In this paper virus-induced gene silencing (VIGS) is used to show that induction of the expression of transcription factor WRKY53 and phenylalanine ammonia-lyase plays an essential function in resistance to RWA. These findings provide important new knowledge about the RWA resistance mechanism. This information will be of high significance to scientists working to understand the mechanisms that plants use to resist insect attack.
Technical Abstract: Although several wheat genes differentially expressed during the Russian wheat aphid resistance response have recently been identified, their requirement for and specific role in resistance remain unclear. Progress in wheat-aphid interaction research is hampered by inadequate collections of mutant germplasm and difficulty in transforming hexaploid wheat. Virus-induced gene silencing (VIGS) technology is emerging as a viable reverse genetics approach in cereal crops. However, the potential of VIGS for determining aphid resistance gene function in wheat has not been evaluated. We report on the use of recombinant barley stripe mosaic virus (BSMV) to target and silence a WRKY53 transcription factor and an inducible phenylalanine ammonia-lyase (PAL) gene, thought to contribute to aphid defence in a genetically resistant wheat line. After inoculating resistant wheat with the VIGS constructs, transcript abundance was knocked down to levels similar to that observed in susceptible wheat. Notably, the level of PAL expression was also suppressed by the WKRY53 construct, suggesting that these genes operate in the same resistance gene network. A susceptible phenotype was generated for both knockdowns upon aphid infestation, and aphids feeding on silenced plants exhibited a significant increase in fitness compared to aphids feeding on control plants. Altered plant phenotype and changes in aphid behaviour after silencing imply that WKRY53 and PAL play key roles in generating a successful resistance response. This study is the first report on the successful use of VIGS to investigate genes involved in wheat-insect interactions.