Figure 1.

Host plant and endophyte crosstalk. The colonization of endophytes and their interaction with the host plant depends on the type of endophytes. Bacterial endophytes mostly make their entry through apertures formed either through the emergence of lateral roots or the zones of elongation. Fungal endophytes can either be transmitted vertically, i.e., transmission from maternal plants to the progeny seeds, or through their entry as fungal spores through herbivory or insects. Some endophytes also release cell wall–degrading enzymes to make their entry possible. Since these endophytes have specific MAMps, they are not recognized by the host plant PRRs. Endophytes help the plant in stress responses by producing phytohormones and reactive oxygen species (ROS) detoxification. ACC, aminocyclopropane-1-carboxylic acid; ROS, reactive oxygen species; MAMPs, microbe-associated molecular patterns; PR, pathogenesi-related; ET, ethylene; SA, salicylic acid; JA, jasmonic acid; PAMPs, pathogen-associated molecular patterns; PTI, PAMP-triggered immunity; R-avr, resistance gene a virulence effector.