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The current assortment of pot azalea (Rhododendron simsii hybrids) has been created from a relatively narrow basis of collectors material brought from the far east. R. simsii, the main ancestor, originates from hilly areas in China, Thailand, Laos and Burma. However several other species from the Tsutsusi subgenus, from South-Asia and Japan might have contributed e.g. R. indicum, R. mucronatum, and R. scabrum. From the Kunming Institute of Botany (China) 33 seed lots from natural populations in mountain area's with an altitude ranging from 250 to 3500 m were obtained. The majority of these Rhododendron species belong to the Tsutsusi subgenus; 8 are R. simsii. Per population 10 plants were analysed by AFLP using 3 primer combinations. They were compared to the breeders pot azalea genepool (70 plants, some with common pedigree and bud sports). AFLP was performed using the commercially available kit for fluorescent fragment detection on an ABI Prism 377 DNA Sequencer. The genetic diversity of the different gene pools was analysed by comparison of the marker frequencies, by calculating similarity indices, by multivariate analysis and AMOVA. Small differences within populations were observed. Large variation was observed within the R. simsii species and between the different species from the Tsutsusi subgenus. The pot azalea genepool was clearly distinguishable from the Chinese accessions. On dendrograms it was more closely clustered to R. simsii and R. mucronatum than to less related species.For matK sequencing a subset of plants from the Chinese accessions was selected and compared to examples from the breeders pot azalea genepool. For amplification and sequencing 4 primer couples were applied that covered in total a DNA sequence of 2529 bp. Multiple alignment from all sequences was used as template for a phylogenetic analysis. One outgroup was defined for rooted tree construction. The dataset was analysed in three ways: Neighbour Joining b ased clustering, parsimony and maximum likelihood analysis. The topology of the trees achieved by AFLP and matK analysis were compared. Several corresponding clusters could be identified, showing the complementarities of both approaches.

A genomic library was constructed from DNA of two azalea genotypes: a Belgian pot azalea R. simsii hybrid Mevr. Van Belle and a Chinese R. simsii from Daoxian. An enrichment of microsatellite containing sequences was performed as in Van de Wiel et al. (1999). Fragments were sequenced and primers were designed that allow the amplification of the microsatellite repeat. About 220 microsatellite containing clones were selected from the enrichment procedure. Mainly dinucleotide repeats and some trinucleotide repeats were found. The selected primers were tested in a small set of reference varieties to check their value (specificity and polymorphic rate) and to set up the PCR-conditions. Five primer pairs have been tested, two of them gave a specific and polymorphic pattern. They were further screened by radioactive PCR on a selection of 5 plants from the azalea breeders gene pool which included the two genotypes used library construction. These 2 STMS markers uniquely identified the 5 plants. 1.

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