Azalea (Rhododendron simsii hybrids) germplasm from China assessed by means of fluorescent AFLP

The current assortment of pot azalea (Rhododendron simsii hybrids) has been created from a relatively narrow basis of collectors material (botanical gardens, private collections) brought from the far east. R. simsii, the main ancestor, originates from hilly areas in China (Chang Jiang valley), 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 In 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 (ABI-Perkin-Elmer) 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 X. mucronatum than to less related species.