Fig. 1.

Phenotypic characterization of late-flowering plants identified from introgressing A. montbretiana genomic segments into A. alpina pep1. (A) Plants grown for 10 wk after germination. Days to flowering (DTF) after gemination are indicated on the Bottom. IL31 was later flowering than A. montbretiana (Am) and A. alpina pep-1-1. (B) Schematic representation of the genotypes of the IL used for association analysis. Different lines segregating for different fragments of chromosome 2 were chosen. Only chromosomes with introgressions from A. montbretiana are represented. (C) DTF for the ILs represented in B. n = 10 in parental lines, 70 in ILs. Only IL41 segregated for the flowering-time phenotype. The total phenotypic variation and P value are indicated for IL41. Individual plants are represented and color coded by the genotype of the most-associated molecular marker. (D) Physical map of the candidate region, showing markers (faint font) and flowering-time genes (bold font), as well as their physical positions on A. montbretiana chromosome 2 in megabases. The genotype of informative recombinants on chromosome 2 and the flowering time of each line is indicated on the Right. The candidate region that confers late flowering is located between markers E252 and E255, comprising ∼196 kb. (E) DTF of transgenic plants containing the genomic locus of each candidate gene in pep1-1. Only plants containing AmMAR1 showed a late-flowering phenotype. n = 10 to 12 plants. NF, non flowering plants at the end of the experiment. Flowering phenotype is measured in days from germination to the first open flower. Letters indicate statistically significant differences determined by multiple pairwise comparisons using Tukey’s least significant difference (LSD) test (P ≤ 0.05). In all panels, alleles from the recurrent parent (A. alpina pep1-1) are colored green, alleles from the donor (A. montbretiana) are in blue, and heterozygous regions are marked in red.