|BRODERSON, CRAIG - University Of California|
|ALSINA, MIMAR - Institute De Recerca I Tecnologia Agroalimentaries (IRTA)|
|DRAYTON, WILL - University Of California|
|MATTHEWS, MARK - University Of California|
|SHACKEL, KEN - University Of California|
|WADA, HIROSHI - University Of California|
|ZUFFEREY, VIVIAN - Agroscope|
|CHOAT, BRENDAN - Western Sydney University|
Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2012
Publication Date: 11/1/2012
Citation: Mcelrone, A.J., Broderson, C., Alsina, M., Drayton, W., Matthews, M., Shackel, K., Wada, H., Zufferey, V., Choat, B. 2012. Centrifuge technique consistently overestimates vulnerability to water-stress induced cavitation in grapevines as confirmed with high resolution computed tomography. New Phytologist. 196(3):661-665.
Interpretive Summary: Drought can induce air bubble formation in plant vasculature, which in extreme cases can result in plant death. We used an advanced visualization technique to observe air bubble formation in plants subjected to actual and simulated drought experiments. Our data confirmed our previous work that showed that Chardonnay grapevines are less susceptible to air bubble formation than previously thought based on other commonly used techniques.
Technical Abstract: Vulnerability to cavitation is a key variable defining the limits to drought resistance in woody plants (e.g. Kursar et al., 2009). This trait is typically assessed by a vulnerability curve, which can be generated by a range of methods including dehydration (Sperry et al., 1988) air injection (Cochard et al., 1992) and centrifugation (Alder et al. 1997). Results from two recent papers suggest that one of the most widely used methods, the centrifuge technique, overestimates vulnerability to cavitation in species with very long vessels (Choat et al., 2010; Cochard et al., 2010). Both research groups proposed that open vessels contained in the centrifuged samples were responsible for this artifact. Grapevine (Vitis vinifera L.), a liana species known to have unusually long and wide vessels appears to be particularly susceptible to artifacts with the centrifuge method (Choat et al., 2010), but the conclusions of this paper have been challenged by Jacobsen and Pratt (2012). They contend the dehydration technique actually underestimates vulnerability to cavitation in grapevine because the production of gels and/or tyloses causes a decline in maximum specific hydraulic conductivity (Ks max) over time. On the basis of their results and previously published hydraulic data they concluded that the centrifuge technique is the most appropriate technique to estimate vulnerability to embolism (see details in Jacobsen and Pratt 2012). Here we demonstrate that declining Ks max did not influence the results of Choat et al. (2010) and present new evidence from high resolution computed tomography (HRCT) to support our original conclusions and refute those of Jacobsen and Pratt (2012). We also contend that the analysis of previous literature presented in Jacobsen and Pratt (2012) was over simplified and obscured the specific comparison of cavitation resistance in current year shoots of grapevine. Overall, the findings presented in Jacobsen and Pratt (2012) for V. vinifera cv. Glenora are in direct contrast to published and unpublished results generated by our research groups for other V. vinifera varieties.