The effects of atmospheric composition, climate, and herbivory on plant secondary metabolism and volatile organic carbon emissions

Quantifying the biosynthesis and emission of terpenes by plants is necessary to understand ecological interactions and improve global atmospheric models. Many studies have addressed the importance of individual factors influencing terpene production and release into the atmosphere, but few have investigated complex interactions between multiple variables and the resulting chemistry’s effects on interactions between organisms across multiple trophic levels. To address this gap in our knowledge, I conducted a series of experiments to examine abiotic and biotic controls over terpene synthesis and emission in Poplar x canescens and Pinus edulis, in which terpenes play prominent roles in plant physiological protection (isoprene) and defense (monoterpenes). Increases in atmospheric CO2 resulted in a smaller contribution of stored extra-chloroplastic carbon towards isoprene biosynthesis and a larger investment from recently assimilated carbon in poplar. In addition to climate change scenarios, it is also critical to understand how abiotic and biotic processes affect terpene concentrations and emissions in situ. Tiger moth herbivory increased pinyon pine monoterpene fluxes three to six fold during spring feeding, but summer drought decreased emissions while maintaining high levels of foliar concentrations. Following a release from drought stress, previously damaged pinyon pines exhibited significantly higher emission rates, potentially due to a drought delayed stimulation of induced monoterpene synthesis. I then performed a series of artificial diet experiments investigating how herbivore-induced monoterpenes observed in the field influences insect performance. While the synergistic effect of all monoterpenes present resulted in a trade-off between investment in immunity and growth, diets containing monoterpene levels mimicking herbivore damage encouraged further herbivory with no increase in growth but enhanced immunity to parasitoid infection. To further isolate temperature versus water status controls on monoterpene dynamics, I conducted a pinyon pine transplant experiment. Drought had little influence over the production of foliar monoterpenes, which is largely under genetic control. However, observed stomatal control over emission rates suggests that plant ecophysiology plays a much larger role in controlling monoterpene fluxes than previously thought. Together, my research provides novel insights into the underestimated contribution of ecophysiology in understanding the role of terpenes in higher trophic level interactions and coevolutionary processes

Mickie Bhatia: Embryonic stem cells come of age

Mickie Bhatia wants to tap into the therapeutic potential of human stem cells, and he's finding ways to overcome the obstacles that stand in his way

Tree defence and bark beetles in a drying world: carbon partitioning, functioning and modelling.

Drought has promoted large-scale, insect-induced tree mortality in recent years, with severe consequences for ecosystem function, atmospheric processes, sustainable resources and global biogeochemical cycles. However, the physiological linkages among drought, tree defences, and insect outbreaks are still uncertain, hindering our ability to accurately predict tree mortality under on-going climate change. Here we propose an interdisciplinary research agenda for addressing these crucial knowledge gaps. Our framework includes field manipulations, laboratory experiments, and modelling of insect and vegetation dynamics, and focuses on how drought affects interactions between conifer trees and bark beetles. We build upon existing theory and examine several key assumptions: (1) there is a trade-off in tree carbon investment between primary and secondary metabolites (e.g. growth vs defence); (2) secondary metabolites are one of the main component of tree defence against bark beetles and associated microbes; and (3) implementing conifer-bark beetle interactions in current models improves predictions of forest disturbance in a changing climate. Our framework provides guidance for addressing a major shortcoming in current implementations of large-scale vegetation models, the under-representation of insect-induced tree mortality

Drought supersedes warming in determining volatile and tissue defenses of piñon pine (Pinus edulis)

Trees are suffering mortality across the globe as a result of drought, warming, and biotic attacks. The combined effects of warming and drought on in situ tree chemical defenses against herbivory have not been studied to date. To address this, we transplanted mature pinon pine trees-a well-studied species that has undergone extensive drought and herbivore-related mortality-within their native woodland habitat and also to a hotter-drier habitat and measured monoterpene emissions and concentrations across the growing season. We hypothesized that greater needle temperatures in the hotter-drier site would increase monoterpene emission rates and consequently lower needle monoterpene concentrations, and that this temperature effect would dominate the seasonal pattern of monoterpene concentrations regardless of drought. In support of our hypothesis, needle monoterpene concentrations were lower across all seasons in trees transplanted to the hotter-drier site. Contrary to our hypothesis, basal emission rates (emission rates normalized to 30 degrees C and a radiative flux of 1000 mu mol m(-2) s(-1)) did not differ between sites. This is because an increase in emissions at the hotter-drier site from a 1.5 degrees C average temperature increase was offset by decreased emissions from greater plant water stress. High emission rates were frequently observed during June, which were not related to plant physiological or environmental factors but did not occur below pre-dawn leaf water potentials of -2 MPa, the approximate zero carbon assimilation point in pinon pine. Emission rates were also not under environmental or plant physiological control when pre-dawn leaf water potential was less than -2 MPa. Our results suggest that drought may override the effects of temperature on monoterpene emissions and tissue concentrations, and that the influence of drought may occur through metabolic processes sensitive to the overall needle carbon balance.National Science Foundation, Division of Atmospheric and Geospace Sciences [0919189]; USDA National Institute of Food and Agriculture Hatch project [MONB00389, 228396]; National Science Foundation, Division of Integrative Organismal Systems [1755346]; National Science Foundation Division of Environmental Biology [1552976]; Department of the Energy National Institute for Climate Change Research (Western Region) [DE-FCO2-O6ER64159]; National Science Foundation Macrosystems Biology [EF-1340624, EF-1550756]; Critical Zone Observatories [EAR-1331408]; DIRENet [DEB-0443526]; Biosphere 2 through the Philecology Foundation (Fort Worth, TX); US Environmental Protection Agency (STAR Fellowship Assistance Agreement) [FP-91717801-0]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

BII-Implementation: The causes and consequences of plant biodiversity across scales in a rapidly changing world

The proposed Biology Integration Institute will bring together two major research institutions in the Upper Midwest—the University of Minnesota (UMN) and University of Wisconsin-Madison (UW)—to investigate the causes and consequences of plant biodiversity across scales in a rapidly changing world—from genes and molecules within cells and tissues to communities, ecosystems, landscapes and the biosphere. The Institute focuses on plant biodiversity, defined broadly to encompass the heterogeneity within life that occurs from the smallest to the largest biological scales. A premise of the Institute is that life is envisioned as occurring at different scales nested within several contrasting conceptions of biological hierarchies, defined by the separate but related fields of physiology, evolutionary biology and ecology. The Institute will emphasize the use of ‘spectral biology’—detection of biological properties based on the interaction of light energy with matter—and process-oriented predictive models to investigate the processes by which biological components at one scale give rise to emergent properties at higher scales. Through an iterative process that harnesses cutting edge technologies to observe a suite of carefully designed empirical systems—including the National Ecological Observatory Network (NEON) and some of the world’s longest running and state-of-the-art global change experiments—the Institute will advance biological understanding and theory of the causes and consequences of changes in biodiversity and at the interface of plant physiology, ecology and evolution. INTELLECTUAL MERIT The Institute brings together a diverse, gender-balanced and highly productive team with significant leadership experience that spans biological disciplines and career stages and is poised to integrate biology in new ways. Together, the team will harness the potential of spectral biology, experiments, observations and synthetic modeling in a manner never before possible to transform understanding of how variation within and among biological scales drives plant and ecosystem responses to global change over diurnal, seasonal and millennial time scales. In doing so, it will use and advance state-of-the-art theory. The institute team posits that the designed projects will unearth transformative understanding and biological rules at each of the various scales that will enable an unprecedented capacity to discern the linkages between physiological, ecological and evolutionary processes in relation to the multi-dimensional nature of biodiversity in this time of massive planetary change. A strength of the proposed Institute is that it leverages prior federal investments in research and formalizes partnerships with foreign institutions heavily invested in related biodiversity research. Most of the planned projects leverage existing research initiatives, infrastructure, working groups, experiments, training programs, and public outreach infrastructure, all of which are already highly synergistic and collaborative, and will bring together members of the overall research and training team. BROADER IMPACTS A central goal of the proposed Institute is to train the next generation of diverse integrative biologists. Post-doctoral, graduate student and undergraduate trainees, recruited from non-traditional and underrepresented groups, including through formal engagement with Native American communities, will receive a range of mentoring and training opportunities. Annual summer training workshops will be offered at UMN and UW as well as training experiences with the Global Change and Biodiversity Research Priority Program (URPP-GCB) at the University of Zurich (UZH) and through the Canadian Airborne Biodiversity Observatory (CABO). The Institute will engage diverse K-12 audiences, the general public and Native American communities through Market Science modules, Minute Earth videos, a museum exhibit and public engagement and educational activities through the Bell Museum of Natural History, the Cedar Creek Ecosystem Science Reserve (CCESR) and the Wisconsin Tribal Conservation Association

RELAÇÃO ENTRE A TURBULÊNCIA DO DOSSEL E DISTRIBUIÇÃO VERTICAL DE GASES REATIVOS NA FLORESTA TROPICAL DA AMAZÔNIA CENTRAL

Ozone plays a crucial role in the chemistry of the tropical atmospheric boundary layer. In the rainforest, ozone sources and sinks are complex due to numerous chemical reactions and surface deposition. Turbulent transport controls the vertical distribution of ozone. A field study in the Amazonia, near Manaus, Brazil during 2014 shows different shapes of ozone profiles as a response to changes in air turbulence during night-to-day and day-to-night transitions. During the night-to-day transition following sunrise ozone levels increase within the canopy due to photochemical production and increased vertical mixing. The vertical transport of ozone to the lower layers of the canopy is enhanced after the thermal inversion in the canopy disappears. At night, the ozone deposition to the ground and the foliage in the lower canopy is strong. After midnight, the lower canopy is devoid of ozone. Relatively high gradients of ozone levels within the forest during the nighttime also result from the decoupling between the in- and above-canopy environment that limits the forest-atmosphere ozone exchange. Processes responsible for the vertical distribution ozone are necessary to estimate the oxidation of the plant-emitted gases whose reaction products are aerosol precursors.O ozônio desempenha um papel fundamental na química da camada-limite atmosférica tropical. Sobre uma floresta tropical, as fontes e sumidouros de ozônio são complexas, devido a numerosas reações químicas e à deposição seca e úmida na superfície. O transporte turbulento controla a distribuição vertical de ozônio. Um estudo de campo na Amazônia, nas proximidades de Manaus, Brasil, durante 2014, revelou diferentes formas para o perfil de ozônio dependendo da turbulência atmosférica durante as transições noite-dia e dia-noite.  Após o nascer do sol, os resultados mostram que durante a transição noite-dia os níveis de ozônio aumentam no dossel devido à produção fotoquímica. O transporte vertical de ozônio para os níveis mais baixos do dossel é intensificado depois que a inversão térmica dentro do dossel desaparece.  Durante a noite, o sumidouro de ozônio no solo é forte, em comparação com a deposição nas folhas. Após a meia-noite, a parte mais baixa do dossel não contém mais ozônio, e como resultado os perfis de ozônio deixam de se modificar durante várias horas.  Gradientes relativamente fortes de ozônio dentro da floresta durante o período noturno também aparecem como resultado do desacoplamento entre o dossel e a atmosfera acima da copa. Isso limita as trocas de ozônio entre a floresta e a atmosfera acima. Dado que o ozônio reage com compostos orgânicos emitidos pela vegetação, e que os produtos dessas reações podem se condensar, o resultado final é a produção de aerossóis: desta forma, a distribuição vertical de ozônio é um indicador importante de quais reações são possíveis, e em particular do potencial de produção de aerossóis