Association mapping in sunflower for Sclerotinia Head Rot resistance.
BACKGROUND
Sclerotinia Head Rot (SHR) is one of the most damaging diseases of sunflower in Europe, Argentina, and USA, causing average yield reductions of 10 to 20 %, but leading to total production loss under favorable environmental conditions for the pathogen. Association Mapping (AM) is a promising choice for Quantitative Trait Locus (QTL) mapping, as it detects relationships between phenotypic variation and gene polymorphisms in existing germplasm without development of mapping populations. This article reports the identification of QTL for resistance to SHR based on candidate gene AM.


RESULTS
A collection of 94 sunflower inbred lines were tested for SHR under field conditions using assisted inoculation with the fungal pathogen Sclerotinia sclerotiorum. Given that no biological mechanisms or biochemical pathways have been clearly identified for SHR, 43 candidate genes were selected based on previous transcript profiling studies in sunflower and Brassica napus infected with S. sclerotiorum. Associations among SHR incidence and haplotype polymorphisms in 16 candidate genes were tested using Mixed Linear Models (MLM) that account for population structure and kinship relationships. This approach allowed detection of a significant association between the candidate gene HaRIC_B and SHR incidence (P < 0.01), accounting for a SHR incidence reduction of about 20 %.


CONCLUSIONS
These results suggest that AM will be useful in dissecting other complex traits in sunflower, thus providing a valuable tool to assist in crop breeding.
Instituto de Biotecnología, Centro Investigación en Ciencias Veterinarias y Agronómicas (CICVyA), Instituto Nacional de Tecnología Agropecuaria (INTA), Hurlingham, Buenos Aires, Argentina.
Corina M
CM
Fusari
Julio A
JA
Di Rienzo
Carolina
C
Troglia
Verónica
V
Nishinakamasu
María Valeria
MV
Moreno
Carla
C
Maringolo
Facundo
F
Quiroz
Daniel
D
Alvarez
Alberto
A
Escande
Esteban
E
Hopp
Ruth
R
Heinz
Verónica V
VV
Lia
Norma B
NB
Paniego
D001203:Ascomycota / Q000472:pathogenicity*; D001483:Base Sequence; D029688:Brassica napus / Q000235:genetics; D002874:Chromosome Mapping / Q000379:methods*; D018556:Crops, Agricultural; D018744:DNA, Plant / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics; D005838:Genotype; D006368:Helianthus / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D007178:Inbreeding; D008969:Molecular Sequence Data; D010641:Phenotype; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D040641:Quantitative Trait Loci / Q000235:genetics*; D017422:Sequence Analysis, DNA
D018744:DNA, Plant