What makes a weed a weed? How virus-mediated reverse genetics can help to explore the genetics of weediness

Reverse genetics investigates what a gene does by testing how the plant responds when the specific gene is changed. These techniques have been in use for decades to assess whether a given gene underpins interesting phenotypes and gain insight into the function of gene networks and families. Weed science has only recently entered the “genomic era” in which genomic and reverse genetics approaches are used to address hypotheses. This review focuses on two reverse genetic techniques used on a variety of plants including agricultural weeds, virus-induced gene silencing (VIGS) and virus-mediated overexpression (VOX), explaining the biology behind them and highlighting how these tools may be used for gene function validation in weed species for which no other transgenic approaches have been developed.