Identification of new sources of quantitative resistance in oilseed rape against Leptosphaeria maculans: toward more sustainable management of collar necrosis?

https://bsppjournals.onlinelibrary.wiley.com/doi/10.1111/mpp.70224

Effectors are molecules secreted by the pathogen that facilitate infection of the host plant but can also be recognized by resistant plants, thereby halting or limiting infection. Leptosphaeria maculans has a complex life cycle that includes an early phase of colonization of rapeseed leaves and a late phase of colonization of the stem. Infection is primarily controlled through the use of rapeseed varieties resistant to infection, particularly those carrying specific resistance genes targeting genes encoding effectors expressed during the early stages of infection (“early” effectors, located in dynamic genomic regions rich in repetitive elements). Thus, these resistances can be rapidly bypassed by the pathogen via various molecular mechanisms (deletion, mutations, reduced expression of the gene encoding the recognized effector). To identify new sources of resistance, potentially more durable, the study authors focused on genes encoding effectors expressed during the late stages of infection, located in gene-rich regions. A previous study had thus identified a quantitative resistance that limits the development of collar necrosis, mediated by a gene-for-gene interaction with an effector expressed during the late stages of infection. Here, the authors first determined that genes encoding “late” effectors exhibited specific genomic characteristics and were better conserved in L. maculans populations than those encoding “early” effectors, suggesting that resistance induced by these effectors might be more durable. Subsequently, six genes encoding “late” effectors were selected to phenotype a broad panel of rapeseed genotypes and successfully identified new quantitative resistances to L. maculans, primarily in semi-winter genotypes, validating the value of this genetic group for identifying new sources of resistance.

Contact:  isabelle.fudal@inrae.fr

Affiliated graduate schools: Biosphera et LSH