Development of Microsatellite Markers for Caladium Genetic Studies

As DNA sequence-based molecular markers, microsatellite markers have become a very powerful tool for genetic studies.  No such tool is available in caladium, an ornamental aroid commonly grown as pot or landscape plants.  Previously, attempts were made to transfer microsatellite markers from taro to caladium, but few of taro microsatellite markers could amplify caladium genomic DNA.  In this study, microsatellite markers were developed from ‘Florida Sweetheart’, a popular cultivar resulted from a cross between a lance- and a fancy-leaved cultivars. Sequencing 480 clones led to the identification of 370 clones (77.1%) containing five or more simple sequence repeats. Of 114 pairs of primers designed, 102 pairs amplified fragments of expected sizes and 61.4% of these markers were transferrable to other Caladium species.  To demonstrate the usefulness of these markers, we analyzed the relationships among 10 commercial caladium cultivars (Caladium×hortulanum) and 38 species accessions, using 47 polymorphic markers. A dendrogram based on the binary matrix at 176 alleles grouped C. humboldtii, C. picturatum, C. bicolor, C. schomburgkii and 10 cultivars into one cluster. C. bicolor and C. schomburgkii accessions were most close to the commercial cultivars. Microsatellite data also supports the separation of C. bicolor var ‘rubicundum’ as a new species.  These results indicate a wide range of possible utility for these markers in caladium genetic research.