Biomedical Engineering Reference
In-Depth Information
low-temperature, and other adverse conditions, lignin synthesis is correlated with
synthesis of other phenylpropanoid substances. Chen et al. [
46
] reported that the
total phenolic content and the pisatin and phaseoline content in the flavonoids were
significantly higher than those in susceptible varieties. Zhou et al. [
47
] reported
that, under noninfective
Verticillium
wilt, PAL activity and the content of phenol
and lignin of the rootstock and grafted strains were obviously higher than those of
the control strains. After infection with
Verticillium
wilt, the increasing amplitude
of PAL activity, phenol content, and lignin content was higher than that of the
control group. PAL activity and phenol content have some relevance to disease
resistance to
Verticillium
spp. In buckwheat seedlings and different tissues, the
flavonoid content always varies with the PAL activity, and this relationship is also
reflected in the time sequence. As can be seen, in disease resistance and adversity
resistance, nonlignin metabolism has some relevance for lignin metabolism in the
phenylalanine metabolism. But, relatively little research currently is available on the
degree of relevance in the different plants and the degree of relevance under normal
circumstances.
2.5.5.4
Relationship Between Metabolism of Lignin and Plant Growth
and Development
The growth and differentiation of plants are closely related to the activities of the cell
wall, and lignin is one of the main components of plant cell walls. Since the 1970s,
there have been many reports on the relationship between lignin metabolism and
plant growth and development. Suzuki and Itoh [
48
] analyzed the lignifications of
bamboo terminal buds and 2- to 14-year-old stem nodes, results of which indicated
that the lignification of terminal buds was prior to the extension growth of stems;
the stem node growth was closely related to the degree of lignifications. Through the
study in the clones of the annual cutting alnus, they found that the sequence of the
PAL activity of different clones corresponded to the sequence of the high growth of
clones. Throughout the entire growth period, the PAL activity of alnus clones had a
significant positive correlation with the high growth.
Lignin, as a secondary metabolite in plant growth and development, has impor-
tant biological functions in the growth and development and disease resistance
of plants. In the cell wall lignification process, lignin penetrates into the cell
walls and fills in their framework, which increases the hardness of the cell wall,
enhancing the mechanical and the compressive strengths, promoting the formation
of mechanical tissues, and consolidating the plant body and water conduction.
Because of the chemical characteristics of the lignin, such as the insolubility and
complex phenolic polymer, lignin has hydrophobicity of the cell wall and higher
resistance to pests. Clarifying the physiological effects of lignin would contribute
to better understanding of many biological phenomena of the plant and provide
a scientific basis for industrial and agricultural production, but further studies are
needed in this field.
