Molecular Interactions BetweenLeptosphaeria maculansandBrassicaSpecies

Abstract

Canola is an important oilseed crop, providing food, feed, and fuel around the world. However, blackleg disease, caused by the ascomycete Leptosphaeria maculans, causes significant yield losses annually. With the recent advances in genomic technologies, the understanding of the Brassica napus–L. maculans interaction has rapidly increased, with numerous Avr and R genes cloned, setting this system up as a model organism for studying plant–pathogen associations. Although the B. napus–L. maculans interaction follows Flor's gene-for-gene hypothesis for qualitative resistance, it also puts some unique spins on the interaction. This review discusses the current status of the host–pathogen interaction and highlights some of the future gaps that need addressing moving forward. Expected final online publication date for the Annual Review of Phytopathology, Volume 60 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Large‐scale population survey of Leptosphaeria maculans in France highlights both on‐going breakdowns and potentially effective resistance genes in oilseed rape

“…Leptosphaeria maculans (also named Plenodomus lingam 5 ) is an ascomycete that causes the stem canker (or blackleg disease) of oilseed rape (Brassica napus) which is a concern in all oilseed rape growing regions except China. 6 The fungus has a complex infectious cycle since the main damaging symptom, stem canker, is the result of penetration into leaf tissues, which takes place many months before the stem canker develops, followed by the systemic colonization of the petiole and stems toward the crown tissues in which the fungus remains quiescent for many months. Resistance of B. napus to L. maculans, typically evaluated in the field at the end of the growing season, was initially thought to be of quantitative nature only, i.e.…”

“…10,11 Subsequent steps were made possible by sequencing facilities and reference genomes of the fungus and the plant, 12,13 leading to the cloning of an increasing number of avirulence genes (11 genes cloned to date) and a few plant resistance genes (five genes corresponding to two loci). 6 While many QTLs (quantitative trait loci) contributing to quantitative resistance to L. maculans have been described, 14 breeding efforts have also been devoted to discovering and using major genes for resistance obeying the gene-for-gene concept. However, L. maculans, as do a few other aerial pathogens of crops (e.g.…”

A new set of international Leptosphaeria maculans isolates as a resource for elucidation of the basis and evolution of blackleg disease on Brassica napus

“…To date, 16 major resistance genes have been characterized for the L . maculans–Brassica interaction, with five of these genes cloned (for a review see Borhan et al, 2022). Of the corresponding avirulence genes, 12 have been cloned and characterized, setting up the L .…”

“…Major gene resistance follows the concept of Flor's gene-for-gene interaction, wherein cultivars with particular resistance genes are resistant to disease if the fungal population carries the corresponding avirulence gene (Balesdent et al, 2005;Flor, 1955). To date, 16 major resistance genes have been characterized for the L. maculans-Brassica interaction, with five of these genes cloned (for a review see Borhan et al, 2022). Of the corresponding avirulence genes, 12 have been cloned and characterized, setting up the L. maculans-Brassica system as a model system for understanding host-pathogen interactions.…”

MPSeqM, a tool combining multiplex PCR and high-throughput sequencing to study the polymorphism of eightLeptosphaeria maculansavirulence genes and its application to field surveys in France

“…Monitoring virulent isolates is particularly important for the fungal ascomycete Leptosphaeria maculans , responsible for the stem canker disease of oilseed rape ( Brassica napus ), for the following reasons; (i) the main control measure deployed to limit the impact of the disease is genetic control, including the use of specific resistance ( Rlm ) genes; (ii) L. maculans populations have the potential to rapidly evolve toward virulence, and this has been reported in many instances (Rouxel et al, 2003; Sprague et al, 2006, Zhang et al, 2016); (iii) potentially effective resistance sources are scarce in oilseed rape and the few currently available Rlm genes must be carefully managed to avoid new breakdowns (Borhan et al, 2022; Rouxel and Balesdent, 2017). Until recently, the monitoring of L. maculans populations consisted of large-scale isolate samplings from diseased B. napus plants, followed by inoculation of each isolate on a plant differential set (for instance, Alnajar et al, 2022; Balesdent et al, 2006, 2023; Stachowiak et al, 2006; Zhang et al, 2016).…”