Integration of trinucleotide microsatellites into a linkage map of Citrus

We report the successful assignment of the first seven microsatellite markers to the Citrus RFLP and isozyme map. A total of 14 microsatellite primer pairs were developed and tested for amplification and product-length polymorphism within a population of plants previously used for linkage-map construction. In each case, the successfully assigned microsatellite mapped to the termini of a different linkage group indicating a widespread distribution throughout the genome. Analysis of allele segregation revealed that two of nine microsatellites displayed a significant deviation from expected ratios (P > 0.5). This was compared with other marker types within Citrus and a similar proportion of skewed loci was also found to be present. The analysis of two markers was complicated by the non-amplification of an inherited null allele within the mapping population. The successful integration of microsatellites into the genetic map of Citrus demonstrates the utility of this marker type for genetic analysis within wide intergeneric plant crosses.