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Western Illinois University (2016)

Seasonal variation and potential roles of dark septate fungi in an arid grassland

Ndinga Muniania, Cedric

Titre : Seasonal variation and potential roles of dark septate fungi in an arid grassland

Auteur : Ndinga Muniania, Cedric.,

Université de soutenance : Western Illinois University

Grade : Master of Science (MS) 2016

Résumé
High temperatures and extended drought periods in arid ecosystems promote the colonization of diverse microenvironments by dominant communities of dark septate fungi (DSF). These fungi contribute to soil nutrient cycling, soil stabilization, and plant survival but the roles of individual DSF, their distribution and diversity are still poorly understood. We collected biocrust (lichen, moss, and cyanobacteria-dominated biocrusts) and rhizhosphere soils from the exotic invasive Bromus tectorum and the native Pleuraphis jamesii in an arid grassland near Moab, UT. Seasonal variation of DSF was evaluated using culture-based approaches and compared with fungal community profiles from Illumina sequencing. Our imaging analysis revealed that DSF were 15% more abundant in biocrusts compared to the plant rhizosphere and showed differences in colonization rates by season for the belowground samples (rhizosphere and below biocrust), with an increase in abundance during the summer months. Pleosporales was the dominant order (38%) in both biocrust and rhizosphere soil out of 816 isolated fungi. The most dominant DSF genera included Alternaria, Preussia, Cladosporium, Phoma, and unknown Pleosporales. Similar results were observed in the Illumina sequencing. Seed germination experiments using dominant taxa were conducted on corn to determine their potential roles on plant growth. Cladosporium and Alternaria, showed growth promoting ability with the stimulation of root production and stem elongation. The variation in abundance and colonization of DSF likely reflects adaptations to summer environmental conditions, changes in the abundance of organic matter, as well as a potential increase in plant demand of these taxa when heat and drought conditions are high.

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Page publiée le 29 octobre 2017, mise à jour le 28 mars 2019