PA profiles of a particular genotype were different from one another: a number of
PAs that were present in the leaf tissue at relatively high concentrations were
absent from the leaf surface.
Nevertheless, positive correlations were found for the concentration of all PAs,
that of the free bases, as well as that of a number of individual PAs between
the leaf surface and leaf tissue. Moreover, the total amount of PAs present on the
surface of the leaves was less than 0.01% of the total amount present in the leaf
tissue. This makes it clear that the relationship between the leaf-surface and leaftissue SMs can offer an important new angle to study the insect-plant interaction
mediated by plant SMs.
Keywords
Jacobaea vulgaris · Jacobaea aquatica · Secondary metabolites · Diversity
1
Introduction
At the end of the nineteenth century, Julius Sachs, one of the founders of
plant physiology, realized that plants contained metabolites with no obvious function. Plant physiologist Albrecht Kossel designated the term “secondary” for the
low-molecular-weight and seemingly nonfunctional metabolites occurring within
plants [1, 2]. Meanwhile, others, such as Anton Kerner von Marilaun, Ernst Stahl,
and Leo Errera, found that secondary metabolites protected plants from attack of
animals [1, 3]. These so-called secondary metabolites are usually regarded to include
compounds such as glucosides, saponins, tannins, alkaloids, essential oils, organic
acids, and others, which are different from primary chemicals (primary metabolites,
PMs) with respect to function and occurrence. SMs are not directly involved in the
growth, development, or reproduction of the plant. Very often they occur in specific
taxons [4].
Plants produce a high diversity of secondary metabolites (SMs). The number
of compounds which are identified exceeds 100,000 [5], and the structure of at
least 47,000 SMs has been described [6]. Within a particular species, or individual
plant, a number of major SMs are usually accompanied by several derivatives as
minor components [7]. For instance, 34 glucosinolates were found in Arabidopsis
thaliana [8], and more than 20 indole alkaloids were produced in hairy root culture
from Rauwolfia serpentina [9]. Besides the structural diversity, SMs often show
a large variation in concentration. A good example is the variation in the total
concentration of the Met-derived glucosinolates in leaves of the ecotypes of
A. thaliana, which varied nearly 20-fold in accumulation of glucosinolates [8].
Qualitative and quantitative variation of SM in plants is determined by genetics
[8, 10–13], the environment, and their interaction [14–16].
Besides SMs in leaf tissue, SMs and PMs on the leaf surface most likely play
an important role in accepting a host plant [17, 18]. This has been most well studied
for glucosinolates, a group of SMs present on leaf surface and in leaf tissue of
cruciferous plants and function as defense chemicals against generalist herbivores,
250
D. Cheng
PAs that were present in the leaf tissue at relatively high concentrations were
absent from the leaf surface.
Nevertheless, positive correlations were found for the concentration of all PAs,
that of the free bases, as well as that of a number of individual PAs between
the leaf surface and leaf tissue. Moreover, the total amount of PAs present on the
surface of the leaves was less than 0.01% of the total amount present in the leaf
tissue. This makes it clear that the relationship between the leaf-surface and leaftissue SMs can offer an important new angle to study the insect-plant interaction
mediated by plant SMs.
Keywords
Jacobaea vulgaris · Jacobaea aquatica · Secondary metabolites · Diversity
1
Introduction
At the end of the nineteenth century, Julius Sachs, one of the founders of
plant physiology, realized that plants contained metabolites with no obvious function. Plant physiologist Albrecht Kossel designated the term “secondary” for the
low-molecular-weight and seemingly nonfunctional metabolites occurring within
plants [1, 2]. Meanwhile, others, such as Anton Kerner von Marilaun, Ernst Stahl,
and Leo Errera, found that secondary metabolites protected plants from attack of
animals [1, 3]. These so-called secondary metabolites are usually regarded to include
compounds such as glucosides, saponins, tannins, alkaloids, essential oils, organic
acids, and others, which are different from primary chemicals (primary metabolites,
PMs) with respect to function and occurrence. SMs are not directly involved in the
growth, development, or reproduction of the plant. Very often they occur in specific
taxons [4].
Plants produce a high diversity of secondary metabolites (SMs). The number
of compounds which are identified exceeds 100,000 [5], and the structure of at
least 47,000 SMs has been described [6]. Within a particular species, or individual
plant, a number of major SMs are usually accompanied by several derivatives as
minor components [7]. For instance, 34 glucosinolates were found in Arabidopsis
thaliana [8], and more than 20 indole alkaloids were produced in hairy root culture
from Rauwolfia serpentina [9]. Besides the structural diversity, SMs often show
a large variation in concentration. A good example is the variation in the total
concentration of the Met-derived glucosinolates in leaves of the ecotypes of
A. thaliana, which varied nearly 20-fold in accumulation of glucosinolates [8].
Qualitative and quantitative variation of SM in plants is determined by genetics
[8, 10–13], the environment, and their interaction [14–16].
Besides SMs in leaf tissue, SMs and PMs on the leaf surface most likely play
an important role in accepting a host plant [17, 18]. This has been most well studied
for glucosinolates, a group of SMs present on leaf surface and in leaf tissue of
cruciferous plants and function as defense chemicals against generalist herbivores,
250
D. Cheng