Analysis of the Time Course of the Establishment of Systemic Gene Silencing by Barley Stripe Mosaic Virus Virus-Induced Gene Silencing in Wheat

Wheat is one of the major sources of protein worldwide. Its hexaploidy significantly complicates the identification of genes that may be crucial for improving wheat production to meet the challenges of an increased world population and climate change. Virus-induced gene silencing (VIGS) using Barley stripe mosaic virus (BSMV)-based constructs has proven to be a very useful tool in the analysis of gene function in the hexaploid plant, wheat. However, most published applications of this technique focus on phenotypes that can be observed in the leaves of wheat. A few studies have reported successful VIGS in the spikes of wheat, but this has proven to be more difficult than the seedling leaf assays. This study reports a time course analysis of the movement of BSMV from the site of inoculation into the meristematic region of wheat. It also describes how the photobleaching phenotype resulting from silencing phytoene desaturase (PDS), which is often used as a reporter for VIGS, does not indicate the full extent of where VIGS occurs, and this can mislead scientists as they design silencing studies. These findings provide guidance for more effective VIGS studies to determine the function of genes expressed in the spikes of wheat and may be important for wheat improvement.