|FOFANOV, YURIY - UNIVERSITY OF HOUSTON|
Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2012
Publication Date: 8/15/2012
Citation: Mc Cue, K.F., Ponciano, G.P., Rockhold, D.R., Whitworth, J.L., Gray, S.M., Fofanov, Y., Belknap, W.R. 2012. Generation of PVY coat protein siRNAs in transgenic potatoes resistant to PVY. American Journal of Potato Research. 89(5):374-383. DOI: 10.1007/s12230-012-9257-0.
Interpretive Summary: Global climate change has the potential to quickly alter the crop pest and pathogen distribution and profiles. Ready tools for mobilization of resistance into elite crops will be part of an integrated strategy to maintain and increase agricultural productivity. Virus resistance through generation of viral coat proteins in plant cells has been demonstrated in several crops. The mechanisms of resistance are thought to be due to the production of small RNAs (sRNAs) complimentary to the introduced viral coat protein gene. The mechanisms for generation of sRNA and their suppression of viral replication have only more recently been revealed. This continues to be a rapidly evolving field seeking to understand the role of sRNAs in gene regulation and development. Utilizing deep sequencing of RNAs in potato plants containing the potato virus Y (PVY) coat protein gene we have identified sRNAs produced from the viral coat protein generated in plants exhibiting resistance to PVY in glass house and field studies. These studies help explain the mechanisms of resistance and allow the development of tools for introducing disease resistance and may reduce the need for chemical applications to control insects that spread the disease. Reduction of disease is an important component of increasing agricultural production needed to respond to the demand for an increased food supply for a growing world population.
Technical Abstract: Transgenic potatoes expressing the potato virus Y coat protein (PVY-CP) inverted hairpin RNA (ihRNA) construct driven by the Solanum bulbocastanum ubiquitin 409s promoter exhibited resistance to PVY in glass house studies using PVYNTN and PVYO as inocula and in field studies using naturally occurring PVYNTN and PVYO. Deep sequencing of the small RNA population of transgenic plants indicated high levels of siRNA production from the transgenic hairpin construct. As many as 47 of the top 200 most frequent sRNA reads were attributable to the PVY-CP transgenic construct in Ranger Russet line #5. The S. bulbocastanum 409 control elements are capable of driving high RNA production and combined with the PVY-CP ihRNA construct using the GBSS6 intron as a spacer resulted in efficient hairpin formation and processing for the production of siRNAs that are capable of conferring resistance to infection by PVY in transgenic potato plants. This combination of transgene and transcription strength is suitable for constructing efficient resistance cassettes for crop protection. Putative miRNA in the transgenic plants with homology to resistance gene analogs may be indicative of additional or complimentary resistance mechanisms that may be produced in concert with the PVY siRNAs as a result of PVY-CP RNA being transcribed in the cell.