Plant Genome IV Conference Plant Genome IV Conference
The objective of our mapping studies is to develop a saturated core linkage map for Prunus consisting of molecular markers linked to genes of economic interest that are valuable for improvement of scion and rootstock cultivars. One hundred seven markers have been placed into 9 linkage groups covering about 800 cM of map distance in a Prunus genetic linkage map constructed using an F2 population of peach x almond hybrid. This map is based on RFLP markers coming primarily from a peach mesocarp-specific cDNA library and includes several isozyme loci and other RFLP and RAPD polymorphisms. Using Bulked Segregant Analysis, we have identified RAPD markers linked to several expressed genes [i.e., Y (flesh color); F (flesh adhesion)] in other segregating populations. Using common RAPD markers segregating in both the core mapping populations and the unrelated populations, we were able to combine the data into an expanded map using "JOIN MAP". Additional RFLP markers have been mapped to saturate and consolidate the eight linkage groups. These markers are being screened for linkage to the gene for resistance to rootknot nematode and those controlling shoot growth and habit in a peach intra-specific F2 population. Other topics including map construction, segregation distortion, and the extent of genome coverage will be discussed.