Biogenic emissions in Bamboo: How do physiological constraints influence patterns of emission?

Background/Question/Methods

Biogenic emissions of volatile organic compounds (BVOCs) from plant leaves are a fundamental aspect of biosphere-atmosphere interactions and a key regulator of atmospheric chemistry and physical processing. BVOC emissions from plant leaves can increase levels of tropospheric ozone and seed secondary aerosol formation (SOA), negatively impacting air quality. Understanding the physiological and ecological factors influencing BVOC emission is key to making informed predictions about global change impacts on biosphere-atmosphere interactions.  Patterns of BVOC emission have been shown to vary widely across plant taxa and the specific compounds emitted may differentially impact atmospheric processes.  Although much is known about the atmospheric implications of leaf-level BVOC emissions, less is known about the physiological or ecological factors influencing the evolution of diverse BVOC emission patterns within related species. We have identified the Bamboos as a novel model system for exploring the physiological and ecological factors influencing BVOC emission in plant leaves. 

Results/Conclusions

BVOC emissions were found to be highly variable and species dependent in a survey of 12 species of Bamboo from six genera phylogenetically dispersed throughout the subfamily Bambusoideae. Isoprene, a key BVOC, was the dominant compound emitted by five species with emission rates ranging from 6 to 16 nmol gDW^-1 s^-1. Isoprene-emitting species were found to emit significantly fewer additional BVOCs when analyzed by GCxGC-TOFMS, while non-isoprene emitting species emitted a diverse range of 80 to 200 compounds when leaf-level emissions were analyzed. Results from our studies suggest a functional trade-off between leaf isoprene emission and the emission of other BVOCs compounds in the Bamboo system. In addition, we have examined key physiological parameters thought to impact BVOC emission, including photosynthetic rate and terpenoid precursor DMAPP content, within the same twelve species of Bamboo. We will discuss the physiological and anatomical covariates associated with the diverse BVOC emission pattern we have observed within Bamboo. Results from this work suggest that there may be significant evolutionary and physiological constraints on the patterns of BVOC emission within plant leaves, and potential ecological implications of these physiological trade-offs will be discussed.