In the June issue of New Phytologist, U. Zimmermann et al. published a Tansley review that criticizes the work of many scientists involved in the study of long-distance water transport in plants. Specifically, the review attempts to ‘show that the arguments of the proponents of the Cohesion Theory are completely misleading’. We, the undersigned, believe that this review is misleading in its discussion of the many recent papers which demonstrate that the fundamentals of the Cohesion-Tension theory remain valid (Cochard 2002; Cochard et al. 2001a; Cochard et al. 2000; Cochard et al. 2001b; Comstock 1999; Holbrook et al. 1995; Melcher et al. 1998; Milburn 1996; Pockman et al. 1995; Richter 2001; Sperry et al. 1996; Steudle 1995; Steudle 2001; Stiller and Sperry 1999; Tyree 1997; Tyree 1999; Tyree 2003; Tyree and Cochard 2003; Tyree et al. 2003; Tyree and Zimmermann 2002; Wei et al. 1999a; Wei et al. 1999b). We wish the readers of New Phytologist to know that the Cohesion/Tension theory is widely supported as the only theory consistent with the preponderance of data on water transport in plants.
1.
Guillermo Angeles. Instituto de Ecologia, A.C. Mexico
2.
Barbara Bond,
3.
John S. Boyer,
4.
Tim Brodribb,
5.
J. Renée Brooks*,
6.
Michael J. Burns, formerly
7.
Jeannine Cavender-Bares,
8.
Mike Clearwater,
9.
Hervé Cochard, INRA,
10. Jonathan Comstock,
11. Stephen D. Davis,
12. Jean-Christophe Domec,
13. Lisa Donovan,
14. Frank Ewers,
15.
Barbara
Gartner, Oregon State University, USA
16. Uwe Hacke,
17. Tom Hinckley,
18. N. Michelle Holbrook,
19. Hamlyn G. Jones,
20. Kathleen Kavanagh,
21. Bev Law,
22.
Jorge López-Portillo, Instituto de Ecología, A.C., Mexico
23. Claudio Lovisolo,
24. Tim Martin,
25. Jordi Martínez-Vilalta,
26. Stefan Mayr, University
27. Fredrick C. Meinzer,
28. Peter Melcher,
29. Maurizio Mencuccini,
30. Stephen Mulkey,
31. Andrea Nardini,
32. Howard S. Neufeld,
Appalachian
33. John Passioura,
CSIRO Plant
34.
R. Brandon Pratt, Pepperdine University, USA
35. Serge Rambal, CNRS,
36. Hanno Richter,
Institute of
37. Lawren Sack,
38. Sebastiano Salleo,
39. Andrea Schubert,
40. Paul Schulte,
41. Jed P. Sparks,
42. John Sperry,
43. Robert Teskey,
44. Melvin
* Author for correspondence (tel +1 (541) 754-4684 ; fax +1 (541) 754-4799; email Brooks.ReneeJ@epa.gov)
Cochard, H. 2002. A technique for measuring xylem hydraulic conductance under high negative pressures. Plant, Cell and Environment. 25:815-819.
Cochard, H., T. Ameglio and P. Cruiziat 2001a. The cohesion theory debate continues. Trends in Plant Science. 6:456.
Cochard, H., C. Bodet, T. Ameglio and P. Cruiziat 2000. Cryo-scanning electron microscopy observations of vessel content during transpiration in walnut petioles. Facts or artifacts? Plant Physiology. 124:1191-1202.
Cochard, H., S. Forestier and T. Ameglio 2001b. A new validation of Scholander pressure chamber technique based on stem diameter variations. Journal of Experimental Botany. 52:1361-1365.
Comstock, J.P. 1999. Why Canny's theory doesn't hold water. American Journal of Botany. 86:1077-1081.
Holbrook, N.M., M.J. Burns and C.B. Field 1995. Negative xylem pressures in plants a test of the balancing pressure
technique. Science.
270:1193-1194.
Melcher, P.J., F.C. Meinzer, D.E. Yount, G.H. Goldstein and U. Zimmermann 1998. Comparative measurements of xylem pressure in transpiring and non-transpiring leaves by means of the pressure chamber and the xylem pressure probe. Journal of Experimental Botany. 49:1757-1760.
Milburn, J.A. 1996. Sap ascent in vascular plants: Challengers to the Cohesion Theory ignore the significance of immature xylem and the recycling of Munch water. Annals of Botany. 78:399-407.
Pockman, W.T., J. S. Sperry and J.W. O'Leary 1995. Sustained and significant negative water pressure in xylem. Nature. 378:715-716.
Richter, H. 2001. The cohesion theory debate continues: the pitfalls of cryobiology. Trends in Plant Science. 6:456-457.
Sperry, J.S., N.Z. Saliendra, W.T. Pockman, H. Cochard, P. Cruiziat, S.D. Davis, F.W. Ewers and M.T. Tyree 1996. New evidence for large negative xylem pressures and their measurement by the pressure chamber method. Plant, Cell and Environment. 19:427-436.
Steudle, E. 1995. Trees under tension. Nature. 378:663-664.
Steudle, E. 2001. The cohesion-tension mechanism and the acquisition of water by plant roots. Annual Review of Plant Physiology and Molecular Biology. 52:847-875.
Stiller, V. and J.S. Sperry 1999. Canny's Compensating Pressure Theory fails a test. American Journal of Botany. 86:1082-1086.
Tyree, M.T. 1997. The Cohesion-Tension theory of sap ascent: current controversies. Journal of Experimental Botany. 48:1753-1765.
Tyree, M.T. 1999. The forgotten component of plant water potential: a reply Tissue pressures are not additive in the way M.J. Canny suggests. Plant Biology. 1:598-601.
Tyree, M.T. 2003. The ascent of water. Nature. 423:923.
Tyree, M.T. and H. Cochard 2003. Vessel content of leaves after excision: a test of the Scholander assumption. Journal of Experimental Botany. 54:2133-2139.
Tyree, M.T., H. Cochard and P. Cruiziat 2003. The water-filled versus air-filled status of vessels cut open in air: The 'Scholander assumption' revisited. Plant, Cell and Environment. 26:613-621.
Tyree, M.T. and M.H. Zimmermann 2002. Xylem Structure and the Ascent of Sap. Springer Verlag, Berlin, New York.
Wei, C., E. Steudle and M.T. Tyree 1999a. Water ascent in plants: do ongoing controversies have a sound basis? Trends in Plant Science. 4::372-375.
Wei, C., M.T. Tyree and E. Steudle 1999b. Direct measurement of xylem pressure in leaves of intact maize plants. A test of the Cohesion-Tension theory taking hydraulic architecture into consideration. Plant Physiology. 121:1191-1205.