Preforming floral primordia converge on a narrow range of stages at dormancy despite multiple effects of temperature on development

Phenological studies often focus on relationships between flowering date and temperature or other environmental variables. Yet in species that preform flowers, anthesis is one stage of a lengthy developmental process, and effects of temperature on flower development in the year(s) before flowering are largely unknown. We investigated the effects of temperature during preformation on flower development in Vaccinium vitis-idaea. Using scanning electron microscopy, we established scores for developing primordia and examined effects of air temperature, depth of soil thaw, time of year and previous stage on development. Onset of flower initiation depends on soil thaw, and developmental change is greatest at early stages and during the warmest months. Regardless of temperature and time during the season, all basal floral primordia pause development at the same stage before whole-plant dormancy. Once primordia are initiated, development does not appear to be influenced by air temperature differences within the range of variation among our sites. There may be strong endogenous flower-level controls over development, particularly the stage at which morphogenesis ceases before dormancy. However, the strength of such internal controls in the face of continuing temperature extremes under a changing climate is unclear.

Soil Metatranscriptomes Under Long-Term Experimental Warming and Drying: Fungi Allocate Resources to Cell Metabolic Maintenance Rather Than Decay

Earth’s temperature is rising, and with this increase, fungal communities are responding and affecting soil carbon processes. At a long-term soil-warming experiment in a boreal forest in interior Alaska, warming and warming-associated drying alters the function of microbes, and thus, decomposition of carbon. But what genetic mechanisms and resource allocation strategies are behind these community shifts and soil carbon changes? Here, we evaluate fungal resource allocation efforts under long-term experimental warming (including associated drying) using soil metatranscriptomics. We profiled resource allocation efforts toward decomposition and cell metabolic maintenance, and we characterized community composition. We found that under the warming treatment, fungi allocate resources to cell metabolic maintenance at the expense of allocating resources to decomposition. In addition, we found that fungal orders that house taxa with stress-tolerant traits were more abundant under the warmed treatment compared to control conditions. Our results suggest that the warming treatment elicits an ecological tradeoff in resource allocation in the fungal communities, with potential to change ecosystem-scale carbon dynamics. Fungi preferentially invest in mechanisms that will ensure survival under warming and drying, such as cell metabolic maintenance, rather than in decomposition. Through metatranscriptomes, we provide mechanistic insight behind the response of fungi to climate change and consequences to soil carbon processes.

Comparison of the chemistry and diversity of endophytes isolated from wild-harvested and greenhouse-cultivated yerba mansa (Anemopsis californica)

With this study, we explored the identity and chemistry of fungal endophytes from the roots of yerba mansa [Anemopsis californica (Nutt.) Hook. & Arn. (Saururaceae)], a botanical traditionally used to treat infection. We compared the diversity of fungal endophytes isolated from a wild-harvested A. californica population, and those from plants cultivated for one year in a greenhouse environment. The wild-harvested population yielded thirteen fungal strains (eleven unique genotypes). Of the extracts prepared from these fungi, four inhibited growth of Staphylococcus aureus by >25% at 20 µg/mL, and three inhibited growth of Pseudomonas aeruginosa by ≥20% at 200 µg/mL. By comparison, A. californica roots after one year of cultivation in the greenhouse produced only two unique genotypes, neither of which displayed significant antimicrobial activity. The fungus Chaetomium cupreum isolated from wild-harvested A. californica yielded a new antimicrobial spirolactone, chaetocuprum (1). An additional fourteen known compounds were identified using LC-MS dereplication of the various fungal endophytes. This study provides new insights into the identity and chemistry of A. californica fungal endophytes, and demonstrates the importance of considering growing conditions when pursuing natural product drug discovery from endophytic fungi.