Endophytes: Distribution, Molecular Characterization and Biodiversity Evaluation

Endophytes are considered all microorganisms present within plants that can be cultured in suitable media (MEA, PDA). In addition to mutualistic and commensalistic symbionts, endophytes could include latent pathogens, latent saprotrophs, and early stages of colonization by mycorrhizal fungi and rhizobia. Endophytes inhabit the interior of plant tissues, causing no harm to the host and do not develop external structures, excluding in this way modulating bacteria and mycorrhizal fungi.The intimate relationship between endophytic microorganisms and their hosts involves co-evolutionary processes and may influence the physiology of the plant and also interfere with the presence of other endophytes. This endophyte-plant interaction may have been naturally selected during long climatic changes thus allowing a great genetic variability in endophyte populations that open perspectives for the discovery of improved or new enzymes, drugs, and other products with new and useful properties. In this chapter, endophytes, their ubiquitous occurrence, transmission, techniques of isolation, molecular characterization, biodiversity evaluation and future directions for endophytic exploitation have been focused. In the literature, examples have been summarized that show the functional significance and importance of endophytic fungi and bacteria.Recent studies have demonstrated that these endophytes can be used as vectors to provide new characteristics with biotechnological interest to the host plant. In this aspect, endophytic fungi can be genetically modified and express heterologous genes. They can be used to control pathogens, promote plant growth and produce vitamins, amino acids and vaccines inside the host plant. Therefore, it is extremely important to look at endophytes as microorganisms with biotechnological potential besides their biological role.