Pious Thomas*

Abstract: Endophytic microorganisms mainly include bacteria and fungi which colonise intercellular and intracellular niches of tissues without apparent
adverse effects to the host plants. There is a growing interest of plant biologists in endophytic microbiology for basically in isolation and cultivation of such
microorganisms from plant organs and then demonstrating their beneficial effects on the host-plants. Present knowledge about endophytic microorganisms
is that they share a mutualistic association with the host, perhaps serving as the plant- defence system, and also contributing to plant growth and fitness.
Lately, there is a mounting interest in the exploration and utilization of such endophytes for plant growth promotion, as biocontrol agents against plant
pathogens and pests, for alleviation of abiotic stress and for sourcing of novel biomolecules. Such characterised endophytic bacteria have been identified
and described. Much research on this group of organisms originated from micropropagation research. Tissue-culture systems form one significant tool for studying host-endophyte
associations. The microbial associations bear consequential effects on the success and efficiency of in- vitro cloning / micropropagation technologies.
‘Endophytology’ with the concepts of ‘holobiome’, associated with the plant and endophytes, and ‘hologenome’ comprising plant genome together with the
endophytes’ genomes are assuming great significance in plant biology research with considerable potential applications in agriculture and many other fields.

Keywords: Endophytic microorganisms, Cytobacts, Plant growth promotion,
Plant-microbe interactions, Plant tissue culture.