De Baerdemaeker, Niels

Steppe, Kathy

Van Camp, Janne

Vergeynst, Lidewei

English

Ghent University Academic Bibliography

2nd UGCT seminar 10 September 2015  Micro-CT: a technology for direct visualisation and quantification in plant ecophysiology  Kathy Steppe1, Lidewei L. Vergeynst1, Niels De Baerdemaeker1 and Janne Van Camp1 1Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Gent, Belgium  [email: kathy.steppe@UGent.be]  Keywords: cavitation, hydraulic functioning, pinning, plants, stem growth, vulnerability curves, xylem embolism ABSTRACT  Drought in trees has gained increasing interest because of the recent coupling between forest decline and global change associated droughts (Allen et al. 2010, Anderegg et al. 2012). Drought leads to important changes in the hydraulic functioning of trees, and also has an important impact on radial stem growth (Steppe et al. 2015). To better understand how forests will cope with future droughts, a quantitative analysis of the physiological mechanisms governing drought stress at individual tree level is crucial. To this end, we use micro-CT for direct visualisation and quantification of cavitation, a phase change from liquid water to vapour when the xylem water potential becomes too negative. The resultant air emboli block the xylem conduits and reduce the tree’s ability to move water from soil to leaves. With micro-CT, the content of intact xylem conduits (i.e., water- or air-filled) can be visualised and vulnerability curves (Fig. 1) can be developed (Cochard et al. 2015, Vergeynst et al. 2015). These direct observations assist us to better understand vulnerable of tree species to drought-induced embolism.  Drought-induced changes in the water status of trees have also an important impact on radial stem growth, and wood formation (Steppe et al. 2015). Cambial wounding and pinning is an established method used to assess wood formation in a specific period of time (Gricar et al. 2007). We used micro-CT to enhance our knowledge on anatomical responses to cambial wounding, and to assess stem growth responses in well-watered and drought-stressed trees.     2nd UGCT seminar 10 September 2015   Figure 1: (a) Cumulative acoustic emissions (cum AE, grey symbols, left y-axis) detected by the four sensors (1–4) showed a pattern similar to the number of cavitated vessels (black symbols, right y-axis) counted on micro-CT images when plotted against relative radial diameter shrinkage (∆d/d). The micro-CT cross-sections of the grapevine branch are shown for the beginning (d) and end (b) of the dehydration experiment and at the breakpoint (c). (Vergeynst et al., 2015) REFERENCES Allen, C.D., Macalady, A.K. et al. (2010). "A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests." Forest Ecology and Management 259: 660-684.  Anderegg, W.R.L, Berry, J.A. et al. (2012). "The roles of hydraulic and carbon stress in a widespread climate- induced forest die-off. " Proceedings of the National Academy of Sciences, USA 109: 233-237.  Cochard, H., Delzon, S., and Badel, E. (2015). "X-ray microtomography (micro-CT): a reference technology for high-resolution quantification of xylem embolism in trees." Plant, Cell and Environment 38: 201-206.  Gricar, J., Zupancic, M. et al. (2007). "Wood formation in Norway spruce (Picea abies) studied by pinning and intact tissue sampling method". Wood Research 52:1-9.  Steppe, K., Sterck, F., and Deslauriers, A (2015) "Diel growth dynamics in tree stems: linking anatomy and ecophysiology. " Trends in Plant Science 20: 335-343.  Vergeynst, L.L., Dierick, M., et al. (2015) "Cavitation: a blessing in disguise? New method to establish vulnerability curves and assess hydraulic capacitance of woody tissue." Tree Physiology 35: 400-409. 

Micro-CT: a technology for direct visualisation and quantification in plant ecophysiology

https://biblio.ugent.be/publication/6929681/file/6929685

Micro-CT: a technology for direct visualisation and quantification in plant ecophysiology

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