Germination and epiphytic seed fungi on Festuca roemeri and Danthonia californica

<p>Demographic studies measure drivers of plant fecundity such as seed production and survival, but few address environmental drivers of seed viability, such as germination and dormancy. Variation in climate and seed type may both directly and indirectly alter seed germination via altered fungal pathogen abundance.</p> <p>We examined seed germination and microbial communities of seeds of <i>Danthonia californica</i>, which are either chasmogamous (external, wind-pollinated) or cleistogamous (internal, self-fertilized) and <i>Festuca roemeri</i>, which are solely chasmogamous. Seed populations were sourced across environmental gradients. We tested germination and characterized seed fungal community structure, using high-throughput sequencing.</p> <p>For <i>F. roemeri</i>, maternal plant significantly influenced germination as did climate and pathogens; germination increased in wetter, cooler sites. For <i>D. californica</i>, the main drivers of germination were maternal plant, seed type and pathogens; on average, more chasmogamous seeds germinated. Fungal composition depended on seed type, with fewer fungi associated with cleistogamous seeds. Seed fungal composition varied with climate, plant density and mean proportion of seeds germinated.</p> <p>Putative pathogens that were negatively correlated with germination were more abundant for both <i>Danthonia</i> and <i>Festuca</i> chasmogamous seeds than <i>Danthonia</i> cleistogamous seeds. In <i>D. californica</i>, cleistogamous and chasmogamous<i> </i>seeds contain vastly different fungal communities.</p>