Investigations of barley stripe mosaic virus as a gene silencing vector in barley roots and in Brachypodium distachyon and oat
1 Department of Genetics and Biotechnology, Faculty of Agricultural Sciences, Aarhus University, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
2 Department of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Copenhagen, Denmark
3 Biosystems Division, Risø National Laboratory for Sustainable Energy, Technical University of Denmark, PO Box 49, DK-4000 Roskilde, Denmark
4 Current Address: Department of Gene Expression, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
5 Current Address: Department of Agriculture and Ecology, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
6 Current Address: Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S901-83 Umeå, Sweden
7 Current Address: Section for Sustainable Biotechnology, Department of Biotechnology, Chemistry and Environmental Engineering, Copenhagen Institute of Technology, Aalborg University, Ballerup, Denmark
Plant Methods 2010, 6:26 doi:10.1186/1746-4811-6-26Published: 30 November 2010
Gene silencing vectors based on Barley stripe mosaic virus (BSMV) are used extensively in cereals to study gene function, but nearly all studies have been limited to genes expressed in leaves of barley and wheat. However since many important aspects of plant biology are based on root-expressed genes we wanted to explore the potential of BSMV for silencing genes in root tissues. Furthermore, the newly completed genome sequence of the emerging cereal model species Brachypodium distachyon as well as the increasing amount of EST sequence information available for oat (Avena species) have created a need for tools to study gene function in these species.
Here we demonstrate the successful BSMV-mediated virus induced gene silencing (VIGS) of three different genes in barley roots, i.e. the barley homologues of the IPS1, PHR1, and PHO2 genes known to participate in Pi uptake and reallocation in Arabidopsis. Attempts to silence two other genes, the Pi transporter gene HvPht1;1 and the endo-β-1,4-glucanase gene HvCel1, in barley roots were unsuccessful, probably due to instability of the plant gene inserts in the viral vector. In B. distachyon leaves, significant silencing of the PHYTOENE DESATURASE (BdPDS) gene was obtained as shown by photobleaching as well as quantitative RT-PCR analysis. On the other hand, only very limited silencing of the oat AsPDS gene was observed in both hexaploid (A. sativa) and diploid (A. strigosa) oat. Finally, two modifications of the BSMV vector are presented, allowing ligation-free cloning of DNA fragments into the BSMV-γ component.
Our results show that BSMV can be used as a vector for gene silencing in barley roots and in B. distachyon leaves and possibly roots, opening up possibilities for using VIGS to study cereal root biology and to exploit the wealth of genome information in the new cereal model plant B. distachyon. On the other hand, the silencing induced by BSMV in oat seemed too weak to be of practical use. The new BSMV vectors modified for ligation-free cloning will allow rapid insertion of plant gene fragments for future experiments.