title: Haplotype structure around Bru1 reveals a narrow genetic basis for brown rust resistance in modern sugarcane cultivars.
abstract: Modern sugarcane cultivars (Saccharum spp., 2n = 100-130) are high polyploid, aneuploid and of interspecific origin. A major gene (Bru1) conferring resistance to brown rust, caused by the fungus Puccinia melanocephala, has been identified in cultivar R570. We analyzed 380 modern cultivars and breeding materials covering the worldwide diversity with 22 molecular markers genetically linked to Bru1 in R570 within a 8.2 cM segment. Our results revealed a strong LD in the Bru1 region and strong associations between most of the markers and rust resistance. Two PCR markers, that flank the Bru1-bearing segment, were found completely associated with one another and only in resistant clones representing efficient molecular diagnostic for Bru1. On this basis, Bru1 was inferred in 86 % of the 194 resistant sugarcane accessions, revealing that it constitutes the main source of brown rust resistance in modern cultivars. Bru1 PCR diagnostic markers should be particularly useful to identify cultivars with potentially alternative sources of resistance to diversify the basis of brown rust resistance in breeding programs.
authors.affiliation: Cirad, UMR PVBMT, Saint-Pierre, 97410, La Réunion, France.
authors.forename: L
authors.initials: L
authors.lastname: Costet
authors.forename: L
authors.initials: L
authors.lastname: Le Cunff
authors.forename: S
authors.initials: S
authors.lastname: Royaert
authors.forename: L-M
authors.initials: LM
authors.lastname: Raboin
authors.forename: C
authors.initials: C
authors.lastname: Hervouet
authors.forename: L
authors.initials: L
authors.lastname: Toubi
authors.forename: H
authors.initials: H
authors.lastname: Telismart
authors.forename: O
authors.initials: O
authors.lastname: Garsmeur
authors.forename: Y
authors.initials: Y
authors.lastname: Rousselle
authors.forename: J
authors.initials: J
authors.lastname: Pauquet
authors.forename: S
authors.initials: S
authors.lastname: Nibouche
authors.forename: J-C
authors.initials: JC
authors.lastname: Glaszmann
authors.forename: J-Y
authors.initials: JY
authors.lastname: Hoarau
authors.forename: A
authors.initials: A
authors.lastname: D'Hont
mesh_terms: D001487:Basidiomycota / Q000235:genetics* / Q000276:immunology; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics*; D005819:Genetic Markers; D006239:Haplotypes / Q000235:genetics*; D007113:Immunity, Innate / Q000235:genetics*; D015810:Linkage Disequilibrium; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D031786:Saccharum / Q000235:genetics / Q000382:microbiology*
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers