New vector for simultaneous gene silencing and gene expression in maize
In functional genomic experiments to support maize breeding programs, it is difficult to understand the function of an individual gene due to that gene’s interaction with other molecular features. Furthermore, while it is possible to target multiple genes in genomic experiments, it is not frequently done because iterative, stable genomic transformation is a time-consuming process. Virus-induced gene silencing (VIGS) presents a solution to this problem because VIGS allows for silencing a gene of interest that does not require transformation of the germ line and can be tested in the same generation as transformation. However, there has been difficulty associated with development of VIGS resources for maize. Due to the nature of VIGS, the transformation process and proliferation of the virus in the host generally causes an immune response. This complicates interpretation of a gene-of-interest’s function because that immune response could mask a hypothetical phenotype when the gene is silenced. While stable VIGS plasmids that linger for substantial periods in the host and outlast the immune response represent a possible solution to this, there are insufficient resources in maize for this purpose. Furthermore, many phenotypes of interest in maize breeding occur as a function of multiple genes’ activity, and reducing the expression of a single gene may not provide useful information about the gene of interest. Therefore, a virus that can be used for VIGS in maize that elicits a small-to-no immune response that also allows for silencing multiple genes would have wide utility in functional genomics experiments.
Researchers at Ohio State led by Dr. Wenshuang Xie have characterized a new maize dwarf mosaic virus isolate MDMV-OH5 and used the isolate to construct an improved VIGS vector for functional genetic analysis. MDMV-OH5 elicits minimal immune response and no visible signs of disease compared to the wild-type virus and similar isolates. Importantly, this construct target sequences is able to silence the transcription of up to three host gene targeting sequences and also stably facilitate expression of a GFP reporter. Furthermore, the constructed vector was shown to be very stable, and was confirmed as functional 104 days after introduction. Since the vector is stable and there can be up to three targets, this MDMV-OH5 vector could facilitate high-throughput functional genomics experiments with substantially less labor required than editing the genome or stably transforming the germline. Therefore, MDMV-OH5 represents a significant advancement in the available resources for VIGS in maize.
- Advances virus-induced gene silencing (VIGS) resources in maize
- MDMV-OH5 causes minimal immune response in the host
- Up to three gene targets silenced and reporter expression is stable for more than three months