Cryo analytical microscopy: Multiple applications for plant structure and physiology

Abstract

Carleton University’s cyo-analytical SEM facility deals with a very wide range of specimens from all the sciences. One of its major specializations is the study of plant structure and function, as illustrated by reference to particular research programs, for example: Stabilization of structures that cannot be preserved by conventional fixation and embedding methods. Many plant tissues are constructed of extremely fragile cell walls containing large vacuoles with high turgor pressures within, interspersed with large volumes of air or fluid. Plants which grow under water are a conspicuous example, requiring large internal open channels for the transport of gases to and from the roots. Other fragile tissues and those having cell walls that are impermeable to solvents and resins have been preserved in roots of desert monocotyledons, and in tree roots. Fluids in spaces between cells. We have pioneered the discovery that many intercellular spaces in plant tissues, always believed to contain air, are in fact filled with fluid. These spaces in sugarcane stems (Figs. 1 & 2) have been shown to contain both strong sugar solution, and an endophyte that lives on this sugar and fixes atmospheric nitrogen. The large air spaces (aerenchyma) in some roots, always considered an aeration system, have been shown to contain water some of the time, and to enhance diffusion of solutes in roots. We have also discovered that roots, always considered to be organs for collecting water from soil, also excrete water to the soil at night. Distribution of nutrient ions in plant tissues. Quantitative analysis of nutrient ions (especially potassium) in individual cells of roots, stems and leaves are opening up new perspectives on the acquisition, use and transport of ions in plants. Bubbles of air and water.