[75]. On the same pattern, soil microorganisms like bacteria and fungi affect growth
and health of plants in several ways. These beneficial microbes may provide broadspectrum resistance to insect herbivores. These beneficial microbes adapt plant
defenses against insect herbivores. Beneficial soil microorganisms can regulate
hormone signaling including the jasmonic acid, ethylene, and salicylic acid pathways, consequently changing gene expression, biosynthesis of secondary metabolites, plant defensive proteins and different enzymes, and volatile compounds that
may induce defenses against leaf-chewing as well as phloem-feeding insects [12].
Synthesis of secondary metabolites is unique feature of plants. Secondary metabolites deter herbivores but on the same time protect herbivores from parasitic
infection. However, little is known about the impact of secondary metabolites of
nectar on pollinators. Recently, Richardson and colleagues [13] showed that alkaloids, terpenoids, and iridoid glycosides present in secondary metabolites (~61–81%
of total secondary metabolites) reduced the parasitic load of bumble bee. Besides,
secondary metabolites of plants have other beneficial effects on herbivores such as
enhancing memory and foraging efficiency [48, 76], reducing parasite infection [77],
and controlling pathogenic fungi [78]. Therefore, there are evidences and possibility
that secondary metabolites can play tritrophic interactions among plants, pollinators,
and parasites. However, how this affects bee’s survival and reproduction in respect
of the pros and cons of chemical consumption is yet to be known [13]. Thus there are
strong evidences that host plant and its herbivores/pollinators are in continuous
process to adapt and evolve to match the counter defense. This process of
co-evolution is described in the chapters of this book.
6
Conclusion
Biological processes like pollination, symbiosis, plant damage by herbivore insects,
and volatiles released in atmosphere are complex and produce very small amount of
metabolites. With the development of new tools of chemical analysis like GLC,
HPLC and high-throughput screening along with gene expression using transcriptome analysis paved the way for analyzing, detecting, and identifying these
molecules, small or large, in quantities unnoticeable with old prevailing technology.
These techniques enable us to detect small changes in cell sap, environment, and
even microorganisms and insects. Sensitive image sensors can generate useful but
huge data which need to be used for understanding the plant-insect relationship and
developing resistant varieties [79, 80]. Gene expression technology is also evolving
rapidly to monitor the minute physiological and gene expression changes in plants.
References
1. Ramawat KG, Merillon JM (2007) Biotechnology: secondary metabolites- plants and microbes.
Science Publishers Inc., Enfield, pp 1–565
2. Arora J, Goyal S, Ramawat KG (2010) Biodiversity, biology and conservation of medicinal
plants of Thar Desert. In: Ramawat KG (ed) Desert plants. Springer, Berlin/Heidelberg, pp 3–36
1 Co-evolution of Secondary Metabolites During Biological Competition for. . .
13
and health of plants in several ways. These beneficial microbes may provide broadspectrum resistance to insect herbivores. These beneficial microbes adapt plant
defenses against insect herbivores. Beneficial soil microorganisms can regulate
hormone signaling including the jasmonic acid, ethylene, and salicylic acid pathways, consequently changing gene expression, biosynthesis of secondary metabolites, plant defensive proteins and different enzymes, and volatile compounds that
may induce defenses against leaf-chewing as well as phloem-feeding insects [12].
Synthesis of secondary metabolites is unique feature of plants. Secondary metabolites deter herbivores but on the same time protect herbivores from parasitic
infection. However, little is known about the impact of secondary metabolites of
nectar on pollinators. Recently, Richardson and colleagues [13] showed that alkaloids, terpenoids, and iridoid glycosides present in secondary metabolites (~61–81%
of total secondary metabolites) reduced the parasitic load of bumble bee. Besides,
secondary metabolites of plants have other beneficial effects on herbivores such as
enhancing memory and foraging efficiency [48, 76], reducing parasite infection [77],
and controlling pathogenic fungi [78]. Therefore, there are evidences and possibility
that secondary metabolites can play tritrophic interactions among plants, pollinators,
and parasites. However, how this affects bee’s survival and reproduction in respect
of the pros and cons of chemical consumption is yet to be known [13]. Thus there are
strong evidences that host plant and its herbivores/pollinators are in continuous
process to adapt and evolve to match the counter defense. This process of
co-evolution is described in the chapters of this book.
6
Conclusion
Biological processes like pollination, symbiosis, plant damage by herbivore insects,
and volatiles released in atmosphere are complex and produce very small amount of
metabolites. With the development of new tools of chemical analysis like GLC,
HPLC and high-throughput screening along with gene expression using transcriptome analysis paved the way for analyzing, detecting, and identifying these
molecules, small or large, in quantities unnoticeable with old prevailing technology.
These techniques enable us to detect small changes in cell sap, environment, and
even microorganisms and insects. Sensitive image sensors can generate useful but
huge data which need to be used for understanding the plant-insect relationship and
developing resistant varieties [79, 80]. Gene expression technology is also evolving
rapidly to monitor the minute physiological and gene expression changes in plants.
References
1. Ramawat KG, Merillon JM (2007) Biotechnology: secondary metabolites- plants and microbes.
Science Publishers Inc., Enfield, pp 1–565
2. Arora J, Goyal S, Ramawat KG (2010) Biodiversity, biology and conservation of medicinal
plants of Thar Desert. In: Ramawat KG (ed) Desert plants. Springer, Berlin/Heidelberg, pp 3–36
1 Co-evolution of Secondary Metabolites During Biological Competition for. . .
13