THE ROOT MICROBIOME: COMMUNITY DRIVERS OF THE ENDANGERED VIROLA SURINAMENSIS TROPICAL TREE SPECIES
Open Access
- Author:
- Decker, Alyssa
- Area of Honors:
- Biology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. James Harold Marden, Thesis Supervisor
Dr. Michael Axtell, Thesis Honors Advisor - Keywords:
- microbiome
Virola surinamensis
tropical trees
Fungal ITS
Bacterial 16S
model - Abstract:
- Tropical trees in Panama have shown to be negatively affected by soil from conspecific trees, apparently because of shared susceptibility to pathogens. Interactions in the soil between fungi and plant roots drive community dynamics and diversity. Here, we test the hypothesis that root microbiomes that establish in Virola surinamensis seedlings vary depending on relatedness to the soil inoculum source and affect seedling growth performance. In a greenhouse experiment, seedlings were grown in mother, male, other female (conspecific) and heterospecific inocula. Data were gathered on the fungal and bacterial microbiome using the isolated, sequenced ITS2 region of 158 V. surinamensis seedlings and isolated, sequenced 16S region of 114 seedlings. A custom pipeline, which included the use of QIIME, Mothur, and other bioinformatics tools, was used to assign taxonomy and relative abundance values of fungal and bacterial species present in the soil microbiome. Abundances of some possibly pathogenic fungi (e.g., Sympoventuriaceae, Fusarium sp.,) were positively associated with maternal soil and hence candidates for negative effects of growing near a parent tree. Multiple fungal species were identified as being transmitted in a species-specific and/or sex-specific fashion, where multiple bacterial species were identified as solely sex-specific. Abundance of certain fungal and bacterial taxa was positively associated with the microbiome diversity and seedling growth performance (as was microbiome diversity itself). Data also suggests an interaction between a resistance gene haplotype and the fungal strain that inhabits the seedling, which may have strong effects on the microbiome composition and plant growth. The mechanisms of haplotype strain transmission are currently being revealed in genera of fungi and bacteria, and their impacts on the community dynamics of tropical trees are being defined through practical and theoretical applications.