Magnetic resonance imaging (MRI) is a non-invasive
method widely applied in the study of molecules. The MRI
approach is frequently employed not only in medicine but
also in biological, biochemical, and chemical research. Most
of the papers describing the use of MRI to investigate plant
physiology have emphasized certain aspects of anatomy or
functional morphology [1]. In plant biology, MRI supports
several major activities, namely, the research of the water
and mineral compounds transported within a plant [2], [3],
the determination of plant metabolites [4], [5], the
investigation of cellular processes [6], and the examination
of the growth and development of plants [7]. MRI is also
instrumental towards monitoring water changes in early
somatic embryos (ESEs). Šupálková et al. [8] examine the
influence of the ESEs of spruce treated with cadmium
and/or lead ions for twelve days using multi-instrumental
analytical procedures; these authors employ image analysis
to estimate the growth, a fluorimetric sensor to detect the
viability of enzyme-treated ESEs, and the MRI technique to
facilitate non-destructive measurement of the volume of the
ESEs.
The interaction between the cells plays a fundamental role
in the growth and development of multicellular organisms.
In this context, let us note that
the structural integrity of
plants was described by, for example, Šebánek et al. [9]; it
may also be mentioned that the extracellular matrix (ECM)
issue pertains to Dostál’s [10] topic of the structural
integrity of plant organism [11].
At the early stage of their development, the ESEs are
covered with a special extracellular cell wall layer referred
to as the extracellular matrix surface network (ECMSN),
[12]. Neděla et al. [13], [14], [15] utilized an environmental
scanning electron microscope (ESEM) to describe the ECM
and/or ECMSN in conifers (spruce, pine, and fir) at the
native stage. Arabinogalactan-proteins (AGPs) are
progressively accumulated within the ECMSN, a well known
marker covering the embryogenic cells during the
embryo development. Specific AGPs are essential in
somatic embryogenesis and exhibit the capability of
directing the development of the cells [16]. It is possible that
AGPs may be present as adhesives in the middle lamella to
cement the cell-to-cell contact and they may also be
involved in the adhesion of the callus cell clumps [17]. Two
homogeneous AGPs were purified from the Norway spruce callus cells via ion-exchange and gel-permeation
chromatography followed by enzymatic treatment [18]. The
function of AGPs was recently summarized in a review by
Seifert and Roberts [19].
Our article further extends a related, previously published
paper [20], where the authors conducted 4 experiments:
1) the designing of methods to assess the water amount in
relevant somatic embryos; 2) a comparison of the SNR in
images acquired at different magnetic flux density values of
the basic magnetic field; 3) monitoring the tissue growth via
various techniques; and 4) the segmentation of two
subjectively distinguishable regions in the tissue, with each
of these exhibiting a specific T2 relaxation time. Our
research report develops the work carried out by Mikulka et
al., especially as regards the image processing methodology.
In the given context, the aim of the present article is to
utilize MRI relaxometry in order to visualize the relaxation
times of the early embryogenic tissue (callus) of the Norway
spruce.
No comments:
Post a Comment