When plants experience stress, they become more susceptible to disease, but mycophyllas -- endophytic fungi that live within plant leaves -- may ameliorate some of these negative effects. Stressors such as sea-level rise (SLR), and disturbances, such as storms, affect coastal plant communities; however, it is not known how these processes will affect coastal mycophylla community structure and composition. Determining the effects of SLR and storms may be important in understanding plant community dynamics within coastal systems. Therefore, we addressed the following questions: (1) Do mycophylla communities differ among sympatric wetland plant species? (2) Do coastal processes affect composition and community structure of mycophylla communities in wetland plants? We collected leaf tissue from two wetland plant species, Taxodium distichum and Sagittaria lancifolia, which were grown under different combinations of hydrology (flooded, mesic, or continuous water flow), water quality (0ppt salinity, 0ppt with nutrients, 3ppt, and 6ppt), and sediment. We surface-sterilized the leaf tissue and incubated small tissue fragments on 2% malt extract agar (MEA). Fungal colonies were isolated onto fresh MEA. We classified the fungi into distinct morphospecies and used molecular sequence data from the nuclear ribosomal internal transcribed spacer and large subunit (ca. 1000bp) to estimate species boundaries.
Results/Conclusions:
Taxodium distichum contained greater diversity of mycophyllas than Sagittaria lancifolia. Diversity of mycophyllas in T. distichum was not affected by the combination of water quality and sediment; however, diversity in S. lancifolia decreased in 0ppt with nutrients in the absence of additional sediment. Fungal diversity was unaffected by all other combinations of water quality and sediment addition. Fungal diversity decreased as salinity increased in S. lancifolia, but only in mesic soils, with highest diversity found in the combination of 0ppt with nutrients in mesic soil. In contrast, fungal diversity in T. distichum was the lowest in this treatment combination, though none of the other treatment combinations affected fungal diversity in T. distichum. Finally, the fungi found in this study were not host specific and composition was not different among treatment combinations. The results of this study suggest that, while the fungi found in T. distichum and S. lancifolia do not exhibit host affinity, host identity may influence mycophylla diversity under different stress and disturbance regimes. Coastal mycophyllous fungi may respond differently to SLR and storms, depending on the plant host they inhabit; therefore, evolutionary strategies used by these fungi may be influenced by rising sea levels and increased storm intensities.
