Invited Review: Cryo-scanning electron microscopy (CSEM) in the advancement of functional plant biology. Morphological and anatomical applications

Abstract

Cryo-scanning electron microscopy (CSEM) is reviewed by exploring how the images obtained have changed paradigms of plant functions and interactions with their environment. Its power to arrest and stabilise plant parts in milliseconds, and to preserve them at full hydration for examination at micrometre resolution has changed many views of plant function. For example, it provides the only feasible way of accurately measuring stomatal aperture during active transpiration, and volume and shape changes in guard cells, or examining the contents of laticifers. It has revealed that many xylem conduits contain gas, not liquid, during the day, and that they can be refilled with sap and resume water transport. It has elucidated the management of ice to prevent cell damage in frost tolerant plants and has revealed for the first time inherent biological and physical features of root/soil interactions in the field. CSEM is increasingly used to reveal complementary structural information in studies of metabolism, fungal infection and symbiosis, molecular and genetic analysis.

Effect of drought and heat stresses on plant growth and yield: a review

“…This effect can be further increased due to a decrease in soil-root hydraulic conductance related to root shrinkage, which severely hampers water flow to roots (Carminati et al, 2009 and Willatt, 1983). Recent observations point to a rhizospheric effect onto the water relations of this soil-root interface, involving mucilages, root exudates and possibly solute accumulation (Carminati and Vetterlein, 2013;McCully et al, 2009;Read et al, 2003;Stirzaker and Passioura 1996), which would modulate soil-root contact and water uptake with variations in dry or moist soil (White and Kirkegaard, 2010).…”

“…This effect can be further increased due to a decrease in soil-root hydraulic conductance related to root shrinkage, which severely hampers water flow to roots (Carminati et al, 2009 and Willatt, 1983). Recent observations point to a rhizospheric effect onto the water relations of this soil-root interface, involving mucilages, root exudates and possibly solute accumulation (Carminati and Vetterlein, 2013;McCully et al, 2009;Read et al, 2003;Stirzaker and Passioura 1996), which would modulate soil-root contact and water uptake with variations in dry or moist soil (White and Kirkegaard, 2010).At longer time scales, not only plasticity in water relations but also in root growth will occur during water deficit, with a decrease in root length (reduced growth, increased mortality) in drier parts and an increase in wetter parts (Huang and Eissenstat, 2000;Sekhon et al, 2010). If an increase in root growth can be observed at the onset of water stress, the continuing drought will reduce the overall root growth, resulting from uncoupling between carbon production in leaves and use in root sinks (root apex) (Muller et al, 2011).…”

Vascular Function in Grape Berries across Development and Its Relevance to Apparent Hydraulic Isolation

“…Cryo-scanning electron microscopy (cryoSEM) can be used to determine whether xylem conduits are functional (water filled) or embolized (gas filled) at the time of freezing (McCully et al, 2009). In addition, it provides information on the distribution and concentrations of solutes in the sample.…”

Analysing photonic structures in plants

“…However, fixing techniques sometimes damage the cuticle of the petal surface. Thus, it can often be advantageous to use cryo-SEM [25] in order to image fully hydrated biological tissues in their chemically unmodified state. Here, fresh samples attached to a stage are fixed by cooling using nitrogen slush before being sputter-coated with gold in the antechamber of the Cryo-SEM, maintaining the required low temperatures and avoiding the formation of ice crystals.…”