Engineering Pathogen Resistance in Crop Plants: Current Trends and Future Prospects David B. Collinge, Hans J.L. Jørgensen, Ole S. Lund, and Michael F. Lyngkjær Department of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Copenhagen, Denmark; email: dbc@life.ku.dk, hjo@life.ku.dk, osl@life.ku.dk, mlyn@life.ku.dk Annu. Rev. Phytopathol. 2010. 48:269–91 First published online as a Review in Advance on May 5, 2010 The Annual Review of Phytopathology is online at phyto.annualreviews.org This article’s doi: 10.1146/annurev-phyto-073009-114430 Copyright c  2010 by Annual Reviews. All rights reserved 0066-4286/10/0908/0269$20.00 Key Words transgenic disease resistance, RNAi, signal transduction, antimicrobial proteins, plant biotechnology Abstract Transgenic crops are now grown commercially in 25 countries world- wide. Although pathogens represent major constraints for the growth of many crops, only a tiny proportion of these transgenic crops carry dis- ease resistance traits. Nevertheless, transgenic disease-resistant plants represent approximately 10% of the total number of approved field trials in North America, a proportion that has remained constant for 15 years. In this review, we explore the socioeconomic and biological reasons for the paradox that although technically useful solutions now exist for providing transgenic disease resistance, very few new crops have been introduced to the global market. For bacteria and fungi, the majority of transgenic crops in trials express antimicrobial proteins. For viruses, three-quarters of the transgenics express coat protein (CP) genes. There is a notable trend toward more biologically sophisticated solutions involving components of signal transduction pathways reg- ulating plant defenses. For viruses, RNA interference is increasingly being used. 269 Annu. Rev. Phytopathol. 2010.48:269-291. Downloaded from www.annualreviews.org by Universita degli Studi di Padova on 11/09/10. For personal use only.