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In many cultivated crops, sources of resistance to diseases are sparse and rely on introgression from wild relatives. Agricultural crops often are allopolyploids resulting from interspecific crosses between related species, which are sources of diversity for resistance genes. This is the case for Brassica napus (oilseed rape, canola), an interspecific hybrid between Brassica rapa (turnip) and Brassica oleracea (cabbage). B. napus has a narrow genetic basis and few effective resistance genes against stem canker (blackleg) disease, caused by the fungus Leptosphaeria maculans, are currently available. B. rapa diversity has proven to be a valuable source of resistance (Rlm, LepR) genes, while B. oleracea genotypes were mostly considered susceptible. Here we identified a new resistance source in B. oleracea genotypes from America, potentially effective against French L. maculans isolates under both controlled and field conditions. Genetic analysis of fungal avirulence and subsequent cloning and validation identified a new avirulence gene termed AvrLm14 and suggested a typical gene‐for‐gene interaction between AvrLm14 and the postulated Rlm14 gene. AvrLm14 shares all the usual characteristics of L. maculans avirulence genes: it is hosted in a genomic region enriched in transposable elements and heterochromatin marks H3K9me3, its expression is repressed during vegetative growth but shows a strong overexpression 5–9 days following cotyledon infection, and it encodes a small secreted protein enriched in cysteine residues with few matches in databases. Similar to the previously cloned AvrLm10‐A, AvrLm14 contributes to reduce lesion size on susceptible cotyledons, pointing to a complex interplay between effectors promoting or reducing lesion development. [ABSTRACT FROM AUTHOR]

With 3 figures and 4 tables At the field scale, pollen flow between adjacent fields limits the potential of coexistence of different farming production systems, especially for allogamous crops like oilseed rape whose pollen is disseminated by insects or wind. In this article, we examine the efficiency of cleistogamy in an oilseed rape line which showed between 90% and 99% of flowers closed at flowering, in limiting deposition of allo‐pollen. Five trials were established, consisting of two adjacent blocks, the one sown with the cleistogamous low‐erucic acid line and the other with a classically flowering high‐erucic acid line, used as source of contaminating pollen, itself artificially contaminated with a 1% mix of cleistogamous plants. Analyses showed that cross‐fertilization rates of cleistogamous plants, estimated through erucic acid contents of seeds collected from them, were lower than those generally observed in oilseed rape: it averaged 10.1% on isolated plants within the erucic blocks, reached to the maximum 14% immediately adjacent to the erucic block, then decreased exponentially at higher distances. Cleistogamy appeared therefore as one imperfect means of gene bio‐containment. [ABSTRACT FROM AUTHOR]