Meeting Reports

Let plant hydraulics catch the wave

Abstract

In September 2015, INRA-Aquitaine organized the second international meeting of the Xylem group in Bordeaux.This group gathers scientists interested on structural, functional and ecological aspects of the xylem tissue in plants. The group first organized French meetings between 1999 and 20131 but turned international in 2014. For this second international event, more than 100 scientists from 17 different countries attended the meeting for 3-days. While the majority of the attendees were from the field of plant hydraulics, it is noteworthy that many participants were from different disciplines such as molecular biology, genomics, physiology, physics and ecosystem biology. This is an illustration of the dynamism and of the attractiveness of plant hydraulics. Our objective here is to stress some points that we think are important to consider in order to promote further this discipline in the future and let xylem hydraulics catch the wave.

Let plant hydraulics catch the wave

The history of plant hydraulics goes back to the 15th-16th centuries with the pioneer works of plant physiologists like Grew (1672), Hales (1727) or Reichel (1758), but this field of science was founded by the masterful book of Dixon (1914) Transpiration and the Ascent of Sap in Plants. With the publication of the book of MH Zimmermann (1983) Xylem Structure and the Ascent of Sap the discipline entered into its modern era. Since then, the number of scientists involved in the field has increased exponentially, just as the number of publications (figure 1). Nowadays, plant hydraulics is recognized by several notation agencies as one of the hottest fields of research, as demonstrated by the publication of articles in journals with large audience (e.g. Choat et al. 2012, Rowland et al. 2016).

Since 2014, new ambitions have been formulated in the field of plant hydraulics to foster worldwide collaborations. First, and for the first time in its history, the community of plant hydraulicians is structuring itself into a specific scientific discipline. The success of this international meeting (not only due to the wine tasting evening) is a strong illustration of the emergence of this group. Another very significant step was the creation, in 2014, of a non-for-profit peer-reviewed journal specifically dedicated to this field of research, The Journal of Plant Hydraulics. We are convinced that these two new and perennial events will greatly benefit to the advance of the discipline by favoring exchanges between scientists in the group and by promoting interactions with other disciplines.

The hydraulic and acoustic methods developed during the last 3 decades are now used routinely in numerous labs around the world. This rapid development allowed us to characterize the resistance to embolism of thousands of species (Maherali et al. 2004, Choat et al. 2012, Bouche et al. 2014) but also introduced several methodological flaws as reported very recently by several research groups (Cochard et al. 2010, Choat et al. 2016, Ennajeh et al. 2011, Wheeler et al. 2013, Delzon and Cochard 2014, Torres-Ruiz et al. 2015). During the past few years, the use of breakthrough technologies, such as X-ray tomography, enabled for the first time the direct visualization of embolism formation in intact plants. The conclusions of these observations, repeated now on a large set of plants,change our perception of embolism:its formation and restoration is not as routine as previously thought, but rather forms only under intense water stress conditions (Brodersen et al. 2013, Cochard and Delzon 2013, Cochard et al. 2015, Knipfer et al. 2015, Choat et al. 2016, Bouche et al. 2016).

Figure 1. Number of publications published each year in the field of Plant Hydraulics according to the Web of Science database.

By entering into this new era, plant hydraulicians will have to focus their researches on important and unresolved issues. In this sense, the talks given during this meeting are illustrative of what will look like the research activity in the field of plant hydraulics in the coming years. They are still many uncertainties on the mechanism by which cavitation forms in plants and collaborations with physicists should be reinforced to make progresses into this understanding. Identifying the key anatomical structures implicated in this mechanism are also awaited to unravel these mechanisms, and, more challenging, their molecular basis. At the plant level more researches are needed to identify the functional implications of plant hydraulics on plant water relations in particular and whole plant physiology in general. The links between xylem hydraulics, stomatal function and leaf physiology need to be reevaluated on the light of the recent methodologies. Under more intense water stress, the mechanisms by which hydraulic failure causes plant mortality should deserve more attention. Finally, at a more global scale, researches should focus on the diversity of key hydraulics traits across biomes, species, populations and genotypes or phenotypes if we are to foresee and model the impact of climate change on the stability of plant ecosystems. The future meetings of the Xylem group will be an ideal place to exchange ideas are results and will this contribute to the advance of knowledge in this research field.


Acknowledgements : we thank P Bouche, R Burlett, T Caignard, G Capdeville, N Gonzalez-Munoz, Y Kouzmine, C Lemaire and M Larter, and for helping with the organization of the meeting. We are grateful to A Zanne for the live tweets during the meeting. We appreciated the visit at Chateau Couhinsand the wine tasting.We thank INRA-EFPA, ANR Acoufreezeand LabEx Cote for their financial support and INRA-Bordeaux for the infrastructures.

1 The proceedings of the Xylem group are available here: http://herve.cochard.free.fr/Groupe_Xylem.htm

References

  • Bouche PS, Larter M, Domec J-C, Burlett R, Gasson P, Jansen S, Delzon S. 2014 A broad survey of xylem hydraulic safety and efficiency in conifers. Journal of Experimental Botany 65: 4419-4431. doi:10.1093/jxb/eru218
  • Bouche PS, Delzon S, Choat B, Badel E, Brodribb T, Burlett R, Cochard H, Charra-Vaskou K, Lavigne B, Li S, Mayr S, Morris H, Torres-Ruiz J, Zufferey V, Jansen S. 2016. Are needles of Pinuspinaster more vulnerable to xylem embolism than branches? New insights from X-ray computed tomography. Plant, Cell & Environmentdoi: 10.1111/pce.12680
  • Brodersen CR, McElrone AJ, Choat B, Lee EF, Shackel KA, Matthews MA. 2013. In vivo visualizations of drought-induced embolism spread in Vitisvinifera. Plant Physiology 161: 1820-1829. doi:10.1104/pp.112.212712
  • Choat B, Jansen S, Brodribb TJ, Cochard H, Delzon S et al. 2012. Global convergence in the vulnerability of forests to drought.Nature 491: 752-755. doi:10.1038/nature11688
  • Choat B, Badel E, Burlett R, Delzon S, Cochard H, Jansen S. 2016. Non-invasive measurement of vulnerability to drought induced embolism by X-ray microtomography. Plant Physiologydoi:10.1104/pp.15.00732
  • Cochard H, Herbette S, Barigah T, Badel E, Ennajeh M, Vilagrosa A. 2010. Does sample length influence the shape of xylem embolism vulnerability curves? A test with the Cavitron spinning technique.Plant Cell and Environment 33: 1543-1552. doi:10.1111/j.1365-3040.2010.02163.x
  • Cochard H, Delzon S 2013. Hydraulic failure and repair are not routine in trees. Annals of Forest Science 70: 659-661. doi:10.1007/s13595-013-0317-5
  • Cochard H, Delzon S, 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. doi:10.1111/pce.12391
  • Delzon S, Cochard H. 2014. Recent advances in tree hydraulics highlight the ecological significance of the hydraulic safety margin. New Phytologist 203: 355-358. doi:10.1111/nph.12798
  • Dixon HH. 1914. Transpiration and the ascent of sap in plants. Macmillan, London. doi:10.5962/bhl.title.1943
  • Ennajeh M, Simões F, Khemira H, Cochard H. 2011. How reliable is the double-ended pressure sleeve technique for assessing xylem vulnerability to cavitation in woody Angiosperms? PhysiologiaPlantarum 142: 205-210. doi:10.1111/j.1399-3054.2011.01470.x
  • Grew N. 1672. The anatomy of vegetables.Royal Society, London.
  • Hales S. 1727. Vegetable staticks. W and J Innys and T Woodward, London.
  • Knipfer T, Brodersen CR, Zedan A, Kluepfel DA, McElrone AJ. 2015. Patterns of drought-induced embolism formation and spread in living walnut saplings visualized using X-ray microtomography. Tree physiology 35:744-755. doi:10.1093/treephys/tpv040
  • Maherali H, Pockman WT, Jackson RB. 2004. Adaptive variation in the vulnerability of woody plants to xylem cavitation. Ecology 85: 2184-2199. doi:10.1890/02-0538
  • Reichel GC. 1758. De vasisplantarumspiralibus. Lipsiz.
  • Rowland L et al. 2016. Death from drought in tropical forests is triggered by hydraulics not carbon starvation. Naturedoi: 10.1038/nature15539. doi:10.1038/nature15539
  • Torres-Ruiz JM, Jansen S, Choat B, McElrone A, Cochard H, Brodribb TJ, Badel E, Burlett R, Bouche PS, Brodersen C, Li S, Morris H, Delzon S. 2015. Direct X-ray microtomography observation confirms the induction of embolism upon xylem cutting under tension. Plant Physiology 167: 40-43. doi:10.1104/pp.114.249706
  • Wheeler JK, Huggett BA, Tofte AN, Rockwell FE, Holbrook NM. 2013. Cutting xylem under tension or supersaturated with gas can generate PLC and the appearance of rapid recovery from embolism. Plant, Cell & Environment 36: 1938-1949. doi:10.1111/pce.12139
  • Zimmermann MH. 1983. Xylem structure and the ascent of sap. Springer, Berlin Heidelberg, New York. doi:10.1007/978-3-662-22627-8

Authors


Hervé Cochard

Affiliation : PIAF, INRA, Univ. Clermont-Auvergne, 63000 Clermont-Ferrand,
Country : France

herve.cochard@clermont.inra.fr

José M. Torres-Ruiz

Affiliation : INRA, UMR 1202 BIOGECO, F-33610 Cestas, France; University of Bordeaux, UMR 1202 BIOGECO, F-33600 Pessac, France


Sylvain Delzon

Affiliation : INRA, UMR 1202 BIOGECO, F-33610 Cestas, France; University of Bordeaux, UMR 1202 BIOGECO, F-33600 Pessac, France

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