Symbiosis: The Art of Living

Plants are the very foundations of life on the earth. Almost all the divisions of plant kingdom — namely bryophytes, pteridophytes, gymnosperms, and angiosperms — form a symbiotic relationship with bacteria, cyanobacteria, or actinomycetes. Symbiotic relationships in which both the species of the association benefit are mutualistic. Mutualistic relations between plants and fungi are recognized, as Mycorrhizae are quite common in nature. The fungus helps the host plant absorb inorganic nitrogen and phosphorus from the soil. Some mycorrhizal fungi also secrete antibiotics which may help protect their host from invasion by parasitic fungi and bacteria. One of the most important examples of mutualism in the overall economy of the biosphere is the symbiotic relationship between certain nitrogen-fixing bacteria and their legume hosts. This chapter deals with all the types of mutualistic symbiotic relationship formed in the plant kingdom.