Importance of microbiology in plant and animals life
Answers
The hologenome concept of evolution postulates that the holobiont (host plus symbionts) with its hologenome (host genome plus microbiome) is a level of selection in evolution. Multicellular organisms can no longer be considered individuals by the classical definitions of the term. Every natural animal and plant is a holobiont consisting of the host and diverse symbiotic microbes and viruses. Microbial symbionts can be transmitted from parent to offspring by a variety of methods, including via cytoplasmic inheritance, coprophagy, direct contact during and after birth, and the environment. A large number of studies have demonstrated that these symbionts contribute to the anatomy, physiology, development, innate and adaptive immunity, and behavior and finally also to genetic variation and to the origin and evolution of species. Acquisition of microbes and microbial genes is a powerful mechanism for driving the evolution of complexity. Evolution proceeds both via cooperation and competition, working in parallel. The hologenome concept of evolution asserts that the holobiont with its hologenome, acts as a unique biological entity and therefore also as a level of selection in evolution (1, 2, 6). During the last few years, numerous experiments have provided support for the hologenome concept. The major arguments for considering the holobiont as a level of selection are the following.
All multicellular organisms contain abundant and diverse microbiota. Often, the number of microbial cells and the sum of their genetic information are above that of their host.
Not only the host genome but also the microbiome can be transmitted between generations with reasonable fidelity and thus maintains the unique properties of the holobiont.
Microbiotas and their hosts interact in a manner that affects the fitness of the holobiont in many ways, including its morphology, development, behavior, physiology, and resistance to disease. Taken together, these interactions characterize the holobiont as a single and unique biological entity (7).
One of the important outcomes of accepting the holobiont as an independent level of selection (6, 8) is that several previously underappreciated modes of genetic variation and evolution become apparent. Genetic variation in the hologenome can be brought about by changes in the host genome and also by changes in the microbiome. Since the microbiome can adjust more rapidly and by more processes than the host genome to environmental dynamics, it plays a fundamental role in the adaptation and evolution of the holobiont.