Finally, it is important to understand how plant fitness is affected
by the presence or absence of particular groups of endophytic
bacteria. Is the presence of ACC deaminase in bacterial endophytes,
which accounts for the effect on plant ethylene levels, the sole
explanatory mechanism? Whereas the deamination of ACC is
potentially very important, there is still some unexplained variation
in the establishment of endophytes in their host plant. Could these
mechanisms enable endophytes to establish outside of their regions
of origin (geographically) and could the issue of geography be
finally explained