The impact of lipid distribution, composition and mobility on xylem water refilling of the resurrection plantMyrothamnus flabellifolia

Abstract

Summary• Lipids play a crucial role in the maintenance of the structural and functional integrity of the water-conducting elements and cells of the resurrection plant Myrothamnus flabellifolia during complete dehydration.• Lipid composition, mobility and distribution within the internodal and nodal xylem regions (including short shoots and leaves) were investigated in the presence and absence of water by using various nuclear magnetic resonance (NMR) spectroscopy and imaging techniques differing greatly in the level of spatial resolution and acquisition of lipid parameters.• Significant findings include: a discontinuity in the branch xylem between an inner zone where no water moves and an outer zone where the water moves; the blocking of water movement in the inner zone by lipids that are not dispersed by water, and the facilitation of water advance in the xylem elements and pits of the outer zone by water-dispersed lipids; the relative impermeability of leaf trace xylem to the rehydrating water and, hence, the relative hydraulic isolation of the leaves.• These results elucidated part of the strategy used by the resurrection plant to cope with extreme drought and to minimize transpirational water loss upon hydration.

Water Uptake and Distribution in Germinating Tobacco Seeds Investigated in Vivo by Nuclear Magnetic Resonance Imaging

“…In dry seeds (Fig. 3A) the proton signal strength is given by the content of water plus lipids in the sample (Schneider et al, 2003;Leubner-Metzger, 2005). The water signal at 4.8 ppm in the 1 H-MAS NMR spectra was the only signal that increased during water uptake (Fig.…”

“…de/) using a Bruker Avance 400 NMR spectrometer (Bruker, Rheinstetten, Germany) with a vertical 9.4 T magnet and a proton resonance frequency of 400 MHz Schneider et al, 2003). For MAS NMR spectroscopy, the intact seeds were placed inside a standard 4-mm o.d.…”

“…1 H-NMR imaging (MRI) is a noninvasive in vivo technique that allows the acquisition of sequential cross-sectional two-dimensional (2D) and threedimensional (3D) images of the spatial distribution of 1 H nuclei (protons; Mansfield and Morris, 1982;Callaghan, 1991;MacFall and van As, 1996;Ratcliffe, 1996;Fountain et al, 1998;Manz et al, 1999Manz et al, , 2003Kamenetsky et al, 2003;Schneider et al, 2003). MRI relies on the principle that 1 H nuclei carry a nonzero spin and therefore a magnetic moment.…”

“…However, some results of water content reported in the literature turned out to be wrong, because hydrogen nuclei of molecules in the seed possess the same mobility as water with a kind of restricted motion (Volke et al, 1996). Therefore, a spectral-resolution enhancement using magic angle spinning (MAS)-1 H-NMR and -13 C NMR spectroscopy, which have only recently emerged as useful tools in plant biology (Bardet et al, 2001;Bardet and Foray, 2003;Schneider et al, 2003), yields much more accurate results. During MAS NMR spectroscopy the intact seeds are rotated at high speed around an axis inclined by 54.7°in relation to the magnetic field, which results in higher spectral resolution and sharper signals (peaks).…”

Leaf surface structures enable the endemic Namib desert grass Stipagrostis sabulicola to irrigate itself with fog water

“…Principally, a moving water front inside a groove is described by the kinetics of the Washburn law [33,34]. The detailed kinetics is dependent on the orientation of the groove and on the direction of the water flow with respect to gravity [35].…”