Virus-Induced Gene Silencing as a Powerful Tool for Functional Analysis of Nodulation In Soybean.

Virus-induced gene silencing (VIGS) is an attractive reverse genetics tool for gene silencing in difficult to transform plants. Although a few VIGS vectors have been developed for soybean, they were never utilised for functional analysis of nodulation, a critical process for improving sustainable soybean cultivation. This is unfortunate, because several genes regulating this process are expressed in the upper parts of the plant, hence remain understudied due to limitations of the commonly used fast Agrobacterium rhizogenes-mediated hairy root transformation and stable transformation approaches. An instance involves components of the autoregulation of nodulation (AON) pathway controlling the optimal number of nodules through systemic long-distance root-shoot-root signalling pathway. We developed a fast and reliable VIGS protocol based on cowpea severe mosaic virus and used it to examine the roles a selected set of known AON genes in nodulation. We demonstrate the effectiveness of cowpea severe mosaic virus-based VIGS in silencing genes in below- and aboveground tissues and establish VIGS as a valuable tool to study nodulation in soybean.