Abstract Title
Soil Fungi Associated with Overwinter Seed Survival in Big Sagebrush (Artemisia tridentata)
Abstract
Seed banks are essential to the persistence of many plant populations, allowing germination timing to coincide with suitable climate or disturbance conditions in variable environments. Big sagebrush, a native Idaho plant species, is declining across its historic range due to climate change, changing fire frequencies, and invasive species. Sagebrush seeds develop in fall and overwinter at the soil or snow surface, before germinating the following spring. In a past experiment, we determined that soil microbes have a negative effect on overwinter sagebrush seed viability. Using amplicon sequencing and the results of our past germination study, we asked: 1) Which pathogens or agents of decomposition are associated with overwinter mortality of big sagebrush seeds in the soil seed bank? 2) Do sagebrush populations vary in their interactions with these soil microbes?
We extracted DNA from each soil sample used in our field experiment for amplicon sequencing, targeting the ITS region to identify relative abundances of fungal taxa. We fit binomial generalized linear mixed models to identify significant correlations between the rarefied relative abundances of fungal genera and the probability of seed survival in R. After correcting for multiple comparisons, our results indicated that the relative abundance of fungal genera Curvibasidium, Exophiala, Microdochium, Pseudolophiotrema, and Pyrenophora were associated with declines in the probability of overwinter seed survival, with significant variation in these correlations between sagebrush populations. This exploratory analysis identifies correlations between fungal taxa and seed survival, but cannot isolate whether genera cause seed mortality. Further, sequencing data captures relative abundances of fungi, and the taxa identified here may be correlated with soil inocula that contained greater absolute abundances of other fungi with negative impacts on seeds. Our results will inform follow-up experiments to identify the impacts of fungi cultured from infested seeds, using laboratory inoculations. Understanding the drivers of sagebrush seed viability is essential to improving seeding efforts that aim to restore sagebrush populations across the Great Basin.
Soil Fungi Associated with Overwinter Seed Survival in Big Sagebrush (Artemisia tridentata)
Seed banks are essential to the persistence of many plant populations, allowing germination timing to coincide with suitable climate or disturbance conditions in variable environments. Big sagebrush, a native Idaho plant species, is declining across its historic range due to climate change, changing fire frequencies, and invasive species. Sagebrush seeds develop in fall and overwinter at the soil or snow surface, before germinating the following spring. In a past experiment, we determined that soil microbes have a negative effect on overwinter sagebrush seed viability. Using amplicon sequencing and the results of our past germination study, we asked: 1) Which pathogens or agents of decomposition are associated with overwinter mortality of big sagebrush seeds in the soil seed bank? 2) Do sagebrush populations vary in their interactions with these soil microbes?
We extracted DNA from each soil sample used in our field experiment for amplicon sequencing, targeting the ITS region to identify relative abundances of fungal taxa. We fit binomial generalized linear mixed models to identify significant correlations between the rarefied relative abundances of fungal genera and the probability of seed survival in R. After correcting for multiple comparisons, our results indicated that the relative abundance of fungal genera Curvibasidium, Exophiala, Microdochium, Pseudolophiotrema, and Pyrenophora were associated with declines in the probability of overwinter seed survival, with significant variation in these correlations between sagebrush populations. This exploratory analysis identifies correlations between fungal taxa and seed survival, but cannot isolate whether genera cause seed mortality. Further, sequencing data captures relative abundances of fungi, and the taxa identified here may be correlated with soil inocula that contained greater absolute abundances of other fungi with negative impacts on seeds. Our results will inform follow-up experiments to identify the impacts of fungi cultured from infested seeds, using laboratory inoculations. Understanding the drivers of sagebrush seed viability is essential to improving seeding efforts that aim to restore sagebrush populations across the Great Basin.