Gene pyramiding enhances durable blast disease resistance in rice

Abstract

Effective control of blast, a devastating fungal disease of rice, would increase and stabilize worldwide food production. Resistance mediated by quantitative trait loci (QTLs), which usually have smaller individual effects than R-genes but confer broad-spectrum or non-race-specific resistance, is a promising alternative to less durable race-specific resistance for crop improvement, yet evidence that validates the impact of QTL combinations (pyramids) on the durability of plant disease resistance has been lacking. Here, we developed near-isogenic experimental lines representing all possible combinations of four QTL alleles from a durably resistant cultivar. These lines enabled us to evaluate the QTLs singly and in combination in a homogeneous genetic background. We present evidence that pyramiding QTL alleles, each controlling a different response to M. oryzae, confers strong, non-race-specific, environmentally stable resistance to blast disease. Our results suggest that this robust defence system provides durable resistance, thus avoiding an evolutionary “arms race” between a crop and its pathogen.

Genomes of 13 domesticated and wild rice relatives highlight genetic conservation, turnover and innovation across the genus Oryza

“…Yet, natural resistance is fragile owing to the rapid evolution of new pathovars that evade host recognition. Stacking of traits from the large array of resistance genes and haplotypes in existing rice germplasm is a realistic approach to build durable resistance 101 . Our sequencing of seven wild relatives of crop species opens a treasure trove of novel resistance haplotypes and loci to sustain this strategy.…”

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

“…On the one hand, diversifying selection has been proposed as a way of exploiting pathogens, for example, via disruptive evolutionary dynamics (Zhan et al., 2015). Alternatively, stacking genes or QTLs in pyramids is also advocated (Djian‐Caporalino et al., 2014; Fukuoka et al., 2015). It is worth noting that while stacking might be of interest when the corresponding infectivity profiles are absent from pathogen populations (Lof et al., 2017), this strategy does not allow the possibility of leveraging decreases in unnecessary infectivity as documented in our study.…”

Genetic Engineering and Sustainable Crop Disease Management: Opportunities for Case-by-Case Decision-Making

“…Creating in planta diversity by gene stacking would be expected to increase the durability of resistance traits, since the target pathogen must overcome all genes in the stack to be fully virulent [37,43,52,58,62,66,[120][121][122]. Stacking conventional R genes with diverse biological effects on the pathogen has been shown to increase resistance durability [58].…”

“…Resistance conferred by individual R genes is often not durable, because widespread deployment of an R genes selects for pathogen strains capable of overcoming it [42, [58][59][60]. The ability to "mine" R genes from plants outside of a crop's breeding pool may be especially important for sustainability, in that it opens a vast pool of R genes potentially useful for breeding.…”