Guiding deployment of resistance in cereals using evolutionary principles

Abstract

Genetically controlled resistance provides plant breeders with an efficient means of controlling plant disease, but this approach has been constrained by practical difficulties associated with combining many resistance genes together and strong evolutionary responses from pathogen populations leading to subsequent resistance breakdown. However, continuing advances in molecular marker technologies are revolutionizing the ability to rapidly and reliably manipulate resistances of all types – major gene, adult plant and quantitative resistance loci singly or multiply into individual host lines. Here, we argue that these advances provide major opportunities to deliberately design deployment strategies in cereals that can take advantage of the evolutionary pressures faced by target pathogens. Different combinations of genes deployed either within single host individuals or between different individuals within or among crops, can be used to reduce the size of pathogen populations and generate patterns of disruptive selection. This will simultaneously limit immediate epidemic development and reduce the probability of subsequent evolutionary change in the pathogen for broader infectivity or increased aggressiveness. The same general principles are relevant to the control of noncereal diseases, but the most efficacious controls will vary reflecting the range of genetic options available and their fit with specific ecology and life-history combinations.

Durable Resistance of Crops to Disease: A Darwinian Perspective

“…Other recent reviews have focused on diverse aspects of durable resistance, including molecular mechanisms (78,109), types of durable resistance used in plant breeding (126), biotechnological approaches (39,96), the relationship of pathogen population structure to durability (93), the biological and genetic bases of quantitative resistance (103,115), the role of pathogen fitness in durable resistance (85), and the deployment of resistance genes to maximize durability (101) and limit pathogen adaptation to cultivars (27). The landmark review by Johnson (68), who introduced the term durable resistance, remains useful for a rigorous understanding of what is meant by durability of resistance, including the diversity of durable resistance and how it can be selected by plant breeders.…”

“…An outstanding success of this strategy was in controlling stem rust of wheat (43,122). Gene pyramiding is expected to be most effective when none of the RES genes have previously been exposed to the pathogen population, and when the parasite is asexual so virulences cannot be reassorted by recombination (27,98,99,101).…”

“…Deployment of RES genes has been proposed as a means of achieving more durable disease control, including planning the regional use of different RES genes over a large area or rotating the use of different RES genes over years (17,27,101). It is highly desirable to avoid a situation in which very large areas of a crop might be overcome by one new, virulent pathogen genotype, but schemes of regional or temporal deployment are difficult to manage and evaluate.…”

Genetic resistance of local upland rice populations from East and North Kalimantan, Indonesia against some important diseases

“…The qualitative (vertical) resistance is a narrow-spectrum resistance mediated by a single or a few major genes that operate in a gene-for-gene fashion (Flor, 1971;Van der Biezen and Jones, 1998;Ohtsuki and Sasaki, 2006). The quantitative (horizontal) resistance is a broad-spectrum resistance refers to resistance against two or more types of pathogens, contributed by multiple genes or quantitative trait loci (QTLs) (Kou and Wang, 2010;Burdon et al 2014). In this study, the two type of resistance might present in the local upland rice population, represented by the resistant plant genotypes against particular disease (Table 5), and resistant plant genotypes against several diseases (Table 6), indicating the existence of vertical and horizontal resistance, respectively.…”

Spatio‐temporal connectivity and host resistance influence evolutionary and epidemiological dynamics of the canola pathogen Leptosphaeria maculans

“…Such ecological homogeneity facilitates the invasion, adaptation and proliferation of plant pathogens within agroecosystems. While a key development in terms of disease control has been the breeding and deployment of crop varieties with genetically controlled resistance to pathogens, resistance has often not proven durable because many of the pathogens that pose the greatest threats to crop yields have repeatedly evolved the ability to overcome resistance genes following their deployment (Burdon, Barrett, Rebetzke, & Thrall, 2014; Burdon, Zhan, Barrett, Papaïx, & Thrall, 2016). Newly adapted pathogen genotypes that result from random mutation or recombination can quickly increase in frequency and spread throughout the landscape.…”