Yan, Muqing (2017-12). PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF PARTIAL RESISTANCE TO BLACK SPOT DISEASE OF DIPLOID ROSA SPP.. Doctoral Dissertation. Thesis uri icon

abstract

  • Black spot disease (Diplocarpon rosae (Lib.) Wolf) of rose is the most important leaf disease of garden roses worldwide. Although partial (horizontal) resistance to black spot has been shown to be moderately heritable, the responsible quantitative trait loci (QTL) remain unidentified. The objective of this study was to generate thousands of informative single nucleotide polymorphism (SNP) markers for genetic linkage and QTL mapping. Five highly black spot resistant breeding lines derived from R. wichuriana 'Basye's Thornless', a moderately susceptible cultivar, and four highly susceptible cultivars with excellent ornamental characteristics were used to generate fifteen diploid populations (2n=2x=14) for this study. The disease severity of 812 field-grown seedlings was assessed on the percentage of foliage covered with lesions (PFS) and the size of the lesions (BLS) rating in June, September, October and November of 2016. Lesion size rating was moderately correlated with the amount of foliage with lesions (r = 0.59). The estimated narrow and broad sense heritability of partial resistance was 0.12-0.54 and 0.53, respectively for PFS, and 0.07-0.42 and 0.58, respectively for BLS indicating that partial resistance to black spot is a moderately heritable trait. By utilizing genotyping by sequencing (GBS) technology, we created a high-density integrated consensus map for diploid roses (ICD) with thousands of informative single nucleotide polymorphism (SNP) markers and known bridge single sequence repeat (SSR) markers. 824 SNPs and 13 SSR bridge markers shared among three individual maps of populations were used to link the three maps to generate the consensus map. As a result, the ICD is composed of 3527 molecular markers covering a total length of 892.2 cM with an average distance between markers of 0.25 cM. The high synteny between the strawberry and diploid rose genome was also clearly demonstrated. One major black spot QTL on LG3 at interval 34-44 cM explaining ~20% of the total phenotypic variance was consistently present in the June, September, October, November and combined analyses. This approach serves as a model study for performing pedigree-based analysis (PBA) on materials with a diverse genetic background. The results will support downstream marker assisted breeding (MAB).
  • Black spot disease (Diplocarpon rosae (Lib.) Wolf) of rose is the most important
    leaf disease of garden roses worldwide. Although partial (horizontal) resistance to black
    spot has been shown to be moderately heritable, the responsible quantitative trait loci
    (QTL) remain unidentified. The objective of this study was to generate thousands of
    informative single nucleotide polymorphism (SNP) markers for genetic linkage and QTL
    mapping.

    Five highly black spot resistant breeding lines derived from R. wichuriana
    'Basye's Thornless', a moderately susceptible cultivar, and four highly susceptible
    cultivars with excellent ornamental characteristics were used to generate fifteen diploid
    populations (2n=2x=14) for this study. The disease severity of 812 field-grown seedlings
    was assessed on the percentage of foliage covered with lesions (PFS) and the size of the
    lesions (BLS) rating in June, September, October and November of 2016. Lesion size
    rating was moderately correlated with the amount of foliage with lesions (r = 0.59). The
    estimated narrow and broad sense heritability of partial resistance was 0.12-0.54 and
    0.53, respectively for PFS, and 0.07-0.42 and 0.58, respectively for BLS indicating that
    partial resistance to black spot is a moderately heritable trait.

    By utilizing genotyping by sequencing (GBS) technology, we created a high-density
    integrated consensus map for diploid roses (ICD) with thousands of informative
    single nucleotide polymorphism (SNP) markers and known bridge single sequence
    repeat (SSR) markers. 824 SNPs and 13 SSR bridge markers shared among three
    individual maps of populations were used to link the three maps to generate the consensus map. As a result, the ICD is composed of 3527 molecular markers covering a
    total length of 892.2 cM with an average distance between markers of 0.25 cM. The high
    synteny between the strawberry and diploid rose genome was also clearly demonstrated.
    One major black spot QTL on LG3 at interval 34-44 cM explaining ~20% of the total
    phenotypic variance was consistently present in the June, September, October,
    November and combined analyses. This approach serves as a model study for
    performing pedigree-based analysis (PBA) on materials with a diverse genetic
    background. The results will support downstream marker assisted breeding (MAB).

publication date

  • December 2017