BACTERIAL ENDOPHYTES IMPROVING PLANT GROWTH

Plants are spontaneously colonized by various microorganisms with rhizospheric, endophytic or epiphytic development. Moreover, plants microbiota can also be enriched, for various purposes, with microbial inoculants. Among microorganisms, bacteria are more abundant, compared to other microbial categories. The most studied, well-known and applied beneficial bacteria are the one colonizing the rhizosphere. However, bacterial endophytes provide similar advantages. Since an intimate bound with their plant host is established, not only the plant is benefiting from the biological traits of the endophytic bacteria, but also the microorganisms are in some way protected by various environmental factors once inside the plant tissue. Plant-endophyte associations are diverse and complex, triggering a high interest, mostly due to their beneficial traits in improving crop performance and plant protection against biotic and abiotic stress. Bacterial endophytes can increase nutrient uptake in the host plants, elicit plant defense reaction and stress tolerance, or prime a faster and stronger plant protection mechanism. Beside the agricultural benefits that can be achieved through endophyte colonization, there are also environmental protection aspects. Some endophytes are indirectly involved in the phytoremediation process, or improve the plant's capacity to colonize new harsher environmental areas. By understanding the mechanisms and functions of endophyte's relationship with their hosts in specific environmental circumstances we can improve the microbial balance for a better use of agricultural inoculants and microbial land-improvers.