Thank you very much, Amrani... The information you provide has helped me a lot.

I agree with Hani that endophytes are not exclusively PGPRs. To my understanding "endophyte" describes the habitat in which the organism is thriving. Therefore, classic endophytes includes PGPR like Bradyrhizobium but also pathogens like Xyllela, Pectobacterium carotovorum etc. .

I reviewed a couple of papers in which endophytes were mentioned solely as commensals and PGPR - to me this is clear missunderstanding. Endophytic lifestyle is based on the ability to colonize the internal tissues of a plant - many pathogens are certainly able to do so.

Best, Mitja

Not all endophytes are PGPRs. They may or may not be beneficial to plants and includes beneficial, neutral and pathogenic to host plant. I am working on endophytic bacteria and I am getting mixed bacterial population. Some are known plant growth promoters and other are pathogenic sp. 

all endophytes are not necessarily plant growth promoters. the plant microbe interactions may not always be beneficial , could be detremantal also

HI Dear Colleague,

Endophytic bacteria can be defined as those bacteria that colonize the internal tissue of the plant showing no external sign of infection or negative effect on their host .Therefore,according to definition of endophytic bacteria, these bacteria can be beneficial and  neutral but not detrimental

I have to disagree slightly,

you will be able to find a lot of bacteria in plants that will be detrimental to the host plant under other circumstances - symbiotic relationships are context specific: If there are other endophytes present which keep opportunistic pathogens in check in any possible way - the aforementioned agents won't cause disease but cannot be described as truly neutral (commensal). 

I know that this is the definition that wikipedia and other sources will show - but in an age where most of our knowledge is based on DNA sequencing, e.g. of bacteria residing in plants that are being placed into drawers after being sequenced in a certain environment, we should reconsider some of the definitions previously established. Possibly make them them weaker to accommodate our shallow knowledge of the underlying ecology.

Best, Mitja

P.S.: this is developing into an interesting discussion