Print PageThe Pacific Northwest is home to three native Rhododendron species: R. macrophyllum, R. occidentale, and R. albiflorum. These Rhododendron spp. are known to be infected with fungal endophytes. However, the community structure of these endophytes in native and cultivated Rhododendron is poorly understood. We hypothesize that endophyte communities are more diverse in native Rhododendron and distinctly different than those in cultivated Rhododendron. Our study targeted the foliar fungal endophyte communities of two native Rhododendron spp. and two non-native commercially cultivated Rhododendron varieties. Leaves were sampled from wild populations of native Rhododendron and nursery grown specimens in commercial nurseries. A parallel culture-dependent (fungal isolation and identification via sequencing of the fungal ITS region) and culture-independent sequencing approach (metagenomic sequencing of the fungal ITS region via 454 technology) are employed. Here we report only on the culture dependent methods as metagenomic analysis is still ongoing. Diversity and community composition of foliar fungal endophytes were compared between (1) natives and commercial cultivars, (2) nurseries and wild populations, (3) host identity, and (4) sampling sites using nonmetric multidimensional scaling (NMS) and multiresponse permutation procedures (MRPP). Initial analysis utilized a morphospecies classification system whereby colony morphology characters are used to distinguish different presumed taxa.
Results/Conclusions
Preliminary results utilizing these morphospecies concepts provided evidence against both the hypotheses of a difference in diversity between endophyte communities in native vs non-native Rhododendron and of the existence of distinct endophyte communities in each group. However, we found that the collection site had the strongest effect on community structure; with a separate unique community assemblage associated with R. occidentale, the only deciduous species included in the study.
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