Skip to main content
2023 ESA Annual Meeting Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Back

Contributed Talk

Session: : Communities: Traits And Functional Diversity 8

COS 301-6 - Influence of leaf-associated yeast diversity on poplar leaf rust disease severity outcomes

Thursday, August 10, 2023
4:45 PM – 5:00 PM PDT
Location: C120-121
Abstract: Plants host diverse communities of fungi that can influence their survival and growth. Many of these fungi grow on the surface or within plant tissues without causing disease, as epiphytes and endophytes, respectively. For instance, Populus trichocarpa hosts fungal endophytes and epiphytes that can reduce leaf rust disease severity caused by Melampsora x columbiana. Filamentous fungi such as Trichoderma and Cladosporium, and yeasts like Filobasidium and Pseudozyma are examples of natural biocontrol agents hosted by poplar plants. The benefit these fungi provide has been observed when they are inoculated onto plants. However, it is unclear how the level of disease protection is influenced by fungal community diversity and composition. We selected seven yeast isolates of Populus trichocarpa, and inoculated two-old-month poplar cuttings with individual solutions of the yeasts and 20 yeast communities of varying richness levels (two yeasts per community up to six yeasts). After two weeks, all plants were inoculated with the pathogen, Melampsora x columbiana rust. Disease was allowed to develop for two weeks before leaves were collected and disease severity was quantified using image analysis. Preliminary results from this experiment suggest that richness of poplar-leaf associated yeast communities was not correlated with lower disease severity, but community composition potentially could influence disease outcomes. To further explore the hypothesis that community composition influences disease severity we set up a second greenhouse experiment. Here, we selected ten yeast isolates of Populus trichocarpa, classified them as antagonistic or facilitators based on results from the first experiment, and inoculated two-old-month poplar cuttings with individual solutions of the yeasts and all the 45 unique pairwise combinations of all the yeasts. After two weeks, all plants were inoculated with the pathogen, Melampsora x columbiana rust. Disease was allowed to develop for two weeks before leaves were collected and disease severity was quantified using image analysis. Furthermore, we also quantified yeast abundances as a proxy of yeast interactions. Data processing is ongoing. Overall, our preliminary results suggest that disease protection is not determined by community diversity, but the presence of particular yeasts within the community that could be associated with the strength of disease modification.