Rusts are one of the most severe threats to cereal crops because new pathogen races emerge regularly, resulting in infestations that lead to large yield losses. In 1999, a new race of stem rust, Puccinia graminis f. sp. tritici (Pgt TTKSK or Ug99), was discovered in Uganda. Most of the wheat and barley cultivars grown currently worldwide are susceptible to this new race. Pgt TTKSK has already spread northward into Iran and will likely spread eastward throughout the Indian subcontinent in the near future. This scenario is not unique to stem rust; new races of leaf rust (Puccinia triticina) and stripe rust (Puccinia striiformis) have also emerged recently. One strategy for countering the persistent adaptability of these pathogens is to stack complete- and partial-resistance genes, which requires significant breeding efforts in order to reduce deleterious effects of linkage drag. These varied resistance combinations are typically more difficult for the pathogen to defeat, since they would be predicted to apply lower selection pressure. Genetical genomics or expression Quantitative Trait Locus (eQTL) analysis enables the identification of regulatory loci that control the expression of many to hundreds of genes. Integrated deployment of these technologies coupled with efficient phenotyping offers significant potential to elucidate the regulatory nodes in genetic networks that orchestrate host defense responses. The focus of this review will be to present advances in genetical genomic experimental designs and analysis, particularly as they apply to the prospects for discovering partial disease resistance alleles in cereals.
Keywords: eQTL, parallel expression, wheat, barley, Puccinia, Triticeae, cereal rusts
Citation: Ballini E, Lauter N and Wise R (2013) Prospects for advancing defense to cereal rusts through genetical genomics. Front. Plant Sci. 4:117. doi: 10.3389/fpls.2013.00117
Received: 19 March 2013; Accepted: 15 April 2013;
Published online: 01 May 2013.
Edited by:Corné M. J. Pieterse, Utrecht University, Netherlands
Reviewed by:Nils Rostoks, University of Latvia, Latvia
Copyright © 2013 Ballini, Lauter and Wise. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.
*Correspondence: Roger Wise, Corn Insects and Crop Genetics Research, Department of Plant Pathology and Microbiology, US Department of Agriculture - Agricultural Research Service, Center for Plant Responses to Environmental Stresses, Iowa State University, 351 Bessey Hall, Ames, IA 50011-1020, USA. e-mail: email@example.com
†Present address: Elsa Ballini, UMR BGPI - TA A-54/K- Equipe riz, SupAgro Montpellier, Département Biologie et Ecologie, Campus International de Baillarguet, 34 398 Montpellier Cedex 5, France.