Genetic mapping of a major gene delaying blooming time in almond

The objective of this study was to determine the genetic basis of late bloo ming in almond. Molecular markers were used to study the Late bloom gene (L b), responsible for a delay of blooming time, in an Fl segregating populati on of 134 plants. Using a qualitative approach, the Lh gene was located on linkage group 4 of the almond map, flanked by markers AG6 and FG3. The quan titative analysis confirmed the presence of a major gene on linkage group 4 , which explained at least 79% of the phenotypic variation. On average, the plants with the Lh allele bloomed 15 days later and the Lb allele showed d ominant gene action. In addition. three RAPD markers associated with the Lb gene were identified by bulked segregant analysis. One was placed at 5.4 c M from Lb and could be used as a diagnostic marker for flowering time.