Debate on the Exploitation of Natural Plant Diversity to Create Late Blight Resistance in Potato

Abstract

This paper reports on a debate on intriguing propositions relating to the scientific, agronomic, societal and economic impact of the BIOEXPLOIT project, focusing on late blight resistance in potato. It discusses (i) whether identifying pathogen effectors will facilitate selecting durable R genes, (ii) whether breeding for durable late blight resistance requires deploying Rpi (for Resistance to Phytophthora infestans) genes, (iii) whether breeding strategies and cultural practices determine the durability of new resistance genes, (iv) whether marker-assisted breeding for Phytophthora infestans resistance is already in the stage of adoption, (v) to what extent genetically-modified organism technology can advance realizing late-blight resistant potato cultivars, and (vi) whether modifying R genes will result in novel broad spectrum resistance.

Distribution and Characterization of Podosphaera macularis Virulent on Hop Cultivars Possessing R6-Based Resistance to Powdery Mildew

“…Measuring pathogenic fitness often is inferred from measurements of fecundity or disease severity, calculation of demographic parameters, or directly through competition studies (Leach et al 2001;Nelson 2012). Fitness penalties associated with enhanced virulence may be relatively small or nonexistent in some instances due to the specific function of the effector, the number of other effectors released by the pathogen, and their functional redundancy (Goverse and Struik 2009;Kwon et al 2008;Michelmore et al 2013;Stirnweis et al 2014), and compensatory mutations in other loci (Gabriel 1999;Laine and Barrès 2013;Wolfe 1984). In the hop powdery mildew pathosystem, it is unknown if the virulence gained by P. macularis in overcoming R6 imposed a fitness penalty on the fungus, and whether there is some residual value in this defeated R gene as a QTL.…”

Plant Breeding: Past, Present and Future

“…Yoshida et al (2013) compared the genomes of 11 herbarium and 15 modern strains and concluded that the original nineteenth century pandemic was caused by a single P. infestans lineage, but that this lineage was not the direct ancestor of the one (US-1) that came to dominate the global P. infestans population during much of the twentieth century. Currently, there is much interest and debate over whether or not these R-genes will be more durable per se or can be deployed in a more durable way (Goverse and Struik 2009). The first lineage to spread from there was HERB-1, which persisted globally for at least half a century.…”

“…S. demissum and S. stoloniferum had provided resistances to late blight and viruses, S. chacoense and S. acaule resistances to viruses, and S. vernei and S. spegazzinii resistances to potato cyst nematodes. Currently there is much debate over whether or not the R-genes for late blight resistance being found in other wild species such as S. bulbocastanum will be more durable per se or can be deployed in a more durable way (Goverse and Struik 2009). The resistances to viruses and cyst nematodes proved valuable in crop production, whereas the S. demissum-derived R-genes failed to provide durable resistance to late blight either singly or in combination due to the evolution of new races of P. infestans (Malcolmson 1969).…”

Root and Tuber Crops

“…Results have been mixed and the most widely grown cultivars today are still usually susceptible to late blight (Forbes et al, 2009). Currently there is much debate over whether or not the R genes for blight resistance being found in other wild species will be more durable per se or can be deployed in a more durable way (Goverse and Struik, 2009). …”