MOLECULAR TAGGING OF THE DWARF BREIZH (BZH) GENE IN BRASSICA-NAPUS

We mapped the dwarf Bzh gene in B. napus with RAPD and RFLP markers. R esearch of the linked markers proceeded in two ways: a random approach through the construction of a detailed genetic map and targeting of t he dwarf gene using both near-isogenic lines (NILs) and the bulked seg regant analysis (BSA) method. The BSA approach was the most efficient in finding DNA markers linked to Bzh, whereas the efficiency of the NI Ls approach was limited by a too great similarity of the genetic backg round between the dwarf donor parent and the recurrent lines. Eight RA PD markers were identified as linked to Bzh, the closest being at 0.8 +/- 0.7 cM. The random genetic mapping approach added markers and exte nded the linkage group containing Bzh. This work represents the first step towards a better understanding of the dwarf mutation, the develop ment of marker-assisted selection, and the cloning of the underlying g ene responsible for dwarfing.