Review: Functional status of xylem through time ($) (Annu Rev Plant Biol)

If you haven’t been paying attention, you may have missed the great advances that have been taking place in xylem research recently. This excellent review by Brodersen et al. is your chance to catch up. Like all aspects of plant science, new tools and techniques have provided tremendous new insights into how plants work. Key to these new insights are non-invasive methods for imaging xylem function, beautifully illustrated and described in this review. Microcomputed tomography (microCT) reveals whether xylem elements are filled with air or water, and has been used to observe the process of embolism removal in grapevine. Medical imaging tools such as NMR and PET are also being applied towards investigating xylem function, and improvements in heat sensors for measuring sap flow noninvasively are also discussed. The authors include a very useful and clear discussion of the difference between conductance and conductivity. Finally, the describe how these advances are being applied from the leaf to ecosystem level, and are becoming invaluable tools as we try to monitor and prevent drought-induced tree deaths as the climate changes. (Summary by Mary Williams) Annu Rev Plant Biol.  10.1146/annurev-arplant-050718-100455