Annika Huber


Annika Huber, PhD candidate

Since I was an undergrad at the University of Bayreuth, Germany, I am highly interested in exploring how plants react to changes in their environment. For my bachelor thesis I explored the influence of flooding on stem growth in oak trees. Dendrological as well as gas exchange measurements before, during and after a flooding event helped me evaluate the flooding tolerance of different oak species.

In my Master’s in Forest and Wood Science at the University of Munich, Germany, I specialized on woody plants and was particularly interested in tree species interactions under various conditions over the growing season. Gas exchange measurements and isotope analysis were the techniques of my choice to evaluate tree performance.

Main research questions:

My current research projects are all focused around plant reaction upon drought stress and are guided by the following questions: Why do plants react differently to drought stress? Which plant organ senses drought stress first, the leaves or the roots? Which kind of long distance signal is signaling drought stress through the plant and where does this signal originate?

Current research projects: 

Root to shoot signaling during drought stress: Stomatal conductance (gs) is mainly determined by the plant water status. Despite a thorough understanding of the role of short-distance signals in guard cell regulation, the relationship between long-distance signals and stomatal regulation is, by contrast, extremely nascent. Likewise, the significance of embolism events for the onset of stomatal closure has yet to be determined. In this project, I simultaneously and continuously monitor changes in hydraulic and electrical long-distance signals noninvasively using acoustic emission measurements and surface electrodes, throughout intact sunflowers prior to and upon imposing two different levels of drought stress. We hypothesize that 1) Long-distance signals leading to stomatal closure originate in plant organs (petioles and roots), most prone to cavitation events; and 2) The interaction between hydraulic and electrical long-distance signals in plants lead to changes in stomatal aperture during drought stress. Initial results provide insights to the intricate connections that exist across plant organ systems in response to drought stress.

Differences in xylem anatomical traits on drought resistance of woody plants: The breakage of the water column (cavitation events) in the xylem tissue during drought stress determines the drought stress tolerance of woody plants. The threshold of these cavitation events varies among tree species. Current research hypothesizes that the degree of xylem vessel connectivity is positively correlated with the risk of embolism occurrence and spreading and therefore highly affects plant drought resistance. We construct 3D models of xylem vessels based on cross-sectional images taken by laser ablation tomography to evaluate the connection between xylem vessel connectivity and cavitation resistance.