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<p>Blackleg (Phoma, <i>Leptosphaeria maculans</i>) is one of the most important diseases affecting rapeseed (<i>Brassica napus</i>, 2n = AACC) worldwide. Although a number of major blackleg resistance genes have been identified in <i>B. napus</i>, finding novel sources of resistance is critical in dealing with this rapidly evolving fungal pathogen. Black mustard (<i>Brassica nigra</i>, 2n = BB) is a highly resistant wild relative species for which at least one blackleg resistance gene has been described (<i>Rlm10</i> on chromosome B4), but which has been rarely investigated as a source of blackleg resistance for introgression breeding (probably because it is self-incompatible, heterozygous, difficult to hybridize with <i>B. napus</i> and until recently lacked the genetic and genomic resources available for the <i>Brassica</i> A- and C-genome species). We produced allohexaploid hybrids (2n = AABBCC) between <i>B. napus</i> and <i>B. nigra</i> followed by two generations of backcrossing to develop a BC<sub>2</sub>F<sub>1</sub> population segregating for inheritance of specific B-genome chromosomes from <i>B. nigra</i>. This population was phenotyped for blackleg resistance using a cotyledon test with blackleg isolate “JN2” (<i>AvrLm4-7</i>,<i> 5–9</i>,<i> 6</i>,<i> 8</i>,<i> 10&#xa0;A-B</i>,<i> 11</i>,<i> S-Lep2</i>) and genotyped with B-genome chromosome-specific markers. Resistance segregated with the presence of chromosome B2 (<i>p</i> &lt; 0.0001). Future work will target the identification or production of introgression lines, and recovery of this genetic locus from the B genome in a rapeseed (2n = AACC) genomic background. Our work highlights the potential of <i>B. nigra</i> and <i>Brassica</i> wild relatives as sources of novel biotic stress resistances.</p>

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Segregating BC2F1 interspecific hybrids between Brassica napus and B. nigra reveal a major effect locus for blackleg resistance on chromosome B2

  • 期刊论文

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  • 发表日期：

    2026年7月4日

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  • Paula Vasquez-Teuber,
  • Roman Gaebelein,
  • Jessica L. Soyer,
  • Thierry Rouxel,
  • Jacqueline Batley,
  • Annaliese S. Mason

摘要

Blackleg (Phoma, Leptosphaeria maculans) is one of the most important diseases affecting rapeseed (Brassica napus, 2n = AACC) worldwide. Although a number of major blackleg resistance genes have been identified in B. napus, finding novel sources of resistance is critical in dealing with this rapidly evolving fungal pathogen. Black mustard (Brassica nigra, 2n = BB) is a highly resistant wild relative species for which at least one blackleg resistance gene has been described (Rlm10 on chromosome B4), but which has been rarely investigated as a source of blackleg resistance for introgression breeding (probably because it is self-incompatible, heterozygous, difficult to hybridize with B. napus and until recently lacked the genetic and genomic resources available for the Brassica A- and C-genome species). We produced allohexaploid hybrids (2n = AABBCC) between B. napus and B. nigra followed by two generations of backcrossing to develop a BC2F1 population segregating for inheritance of specific B-genome chromosomes from B. nigra. This population was phenotyped for blackleg resistance using a cotyledon test with blackleg isolate “JN2” (AvrLm4-7, 5–9, 6, 8, 10 A-B, 11, S-Lep2) and genotyped with B-genome chromosome-specific markers. Resistance segregated with the presence of chromosome B2 (p < 0.0001). Future work will target the identification or production of introgression lines, and recovery of this genetic locus from the B genome in a rapeseed (2n = AACC) genomic background. Our work highlights the potential of B. nigra and Brassica wild relatives as sources of novel biotic stress resistances.