Keywords
Co-evolution · Pollination · Plant defense · Secondary metabolites · Allelopathy ·
Biotic stress
1
Introduction
Photosynthesis is the largest photochemical reaction on the planet Earth producing
carbohydrates. Besides carbohydrates, proteins and oils are other primary metabolites. These metabolites are not only used by humans for nutrients and energy but
also by other animals, birds, insects, and a variety of lower animals and microorganisms. Therefore, there is not only competition between plants for obtaining light,
water, and nutrients but also for protection from harmful biotic predators. Thus life
of the plants is not as simple as it appears and they have to evolve various
morphological and physiological characteristics to fight against all odd situations
and survive. On the same time, predators have to survive by obtaining nutrition from
their host plants and produce progeny by reproduction. How these hosts and their
dependents developed various mechanisms to survive is a focus of this book.
Besides primary metabolites, plants produce various classes of secondary metabolites also, generally in lower quantities than primary metabolites. These secondary
metabolites are synthesized by various pathways mainly from shikimic acid pathway
and mevalonic acid pathway by several steps and from primary metabolites. Three
major classes, alkaloids, phenolics, and terpenes, are recognized for secondary
metabolites, and these secondary metabolites are considered more like waste products, generated by plants, in the absence of excretory systems [1–4]. Secondary
metabolites are present almost in all living organisms, even in bacteria and prominently in immune system-lacking organisms [5]. With the progress of science, now
we know that these metabolites are involved in plant defense, deterrent to predators
and herbivore, and signaling molecules in pollination, animal and insect attraction,
communication between host and pathogen, and various biological events. Various
biological processes in which secondary metabolites play important role are presented in Fig. 1. These events are not only important for the host plant but also for the
survival of microorganisms, insects, and other organisms (plants and animals both).
However, the functions of secondary metabolites are not limited to defense alone.
Synthesis of secondary metabolites demands energy and resources. The total available content of a plant sample is the sum of synthesis and degradation/utilization of
secondary metabolites. Sometimes during the growth phase of the plants, production
of secondary metabolites is minimized, or secondary metabolites are used as substrates [6]. Secondary metabolite content also varies from juvenile to mature state of
the plant, particularly during reproductive stage. Intraspecific variation is reported in
many plant species which is further influenced by latitude [7].
Interactions among organisms influence their population, phenotypes and genotypes. Often these ecological interactions are termed as co-evolution. Some
described co-evolution as perusal of patterns of interaction between two major
groups of organisms with a close and evident ecological relationship, such as plants
4
K. G. Ramawat and S. Goyal
Co-evolution · Pollination · Plant defense · Secondary metabolites · Allelopathy ·
Biotic stress
1
Introduction
Photosynthesis is the largest photochemical reaction on the planet Earth producing
carbohydrates. Besides carbohydrates, proteins and oils are other primary metabolites. These metabolites are not only used by humans for nutrients and energy but
also by other animals, birds, insects, and a variety of lower animals and microorganisms. Therefore, there is not only competition between plants for obtaining light,
water, and nutrients but also for protection from harmful biotic predators. Thus life
of the plants is not as simple as it appears and they have to evolve various
morphological and physiological characteristics to fight against all odd situations
and survive. On the same time, predators have to survive by obtaining nutrition from
their host plants and produce progeny by reproduction. How these hosts and their
dependents developed various mechanisms to survive is a focus of this book.
Besides primary metabolites, plants produce various classes of secondary metabolites also, generally in lower quantities than primary metabolites. These secondary
metabolites are synthesized by various pathways mainly from shikimic acid pathway
and mevalonic acid pathway by several steps and from primary metabolites. Three
major classes, alkaloids, phenolics, and terpenes, are recognized for secondary
metabolites, and these secondary metabolites are considered more like waste products, generated by plants, in the absence of excretory systems [1–4]. Secondary
metabolites are present almost in all living organisms, even in bacteria and prominently in immune system-lacking organisms [5]. With the progress of science, now
we know that these metabolites are involved in plant defense, deterrent to predators
and herbivore, and signaling molecules in pollination, animal and insect attraction,
communication between host and pathogen, and various biological events. Various
biological processes in which secondary metabolites play important role are presented in Fig. 1. These events are not only important for the host plant but also for the
survival of microorganisms, insects, and other organisms (plants and animals both).
However, the functions of secondary metabolites are not limited to defense alone.
Synthesis of secondary metabolites demands energy and resources. The total available content of a plant sample is the sum of synthesis and degradation/utilization of
secondary metabolites. Sometimes during the growth phase of the plants, production
of secondary metabolites is minimized, or secondary metabolites are used as substrates [6]. Secondary metabolite content also varies from juvenile to mature state of
the plant, particularly during reproductive stage. Intraspecific variation is reported in
many plant species which is further influenced by latitude [7].
Interactions among organisms influence their population, phenotypes and genotypes. Often these ecological interactions are termed as co-evolution. Some
described co-evolution as perusal of patterns of interaction between two major
groups of organisms with a close and evident ecological relationship, such as plants
4
K. G. Ramawat and S. Goyal