Our results
supported the hypothesis that medicinal plants are potential
hosts of endophytes with medicinal properties. Although we
did not confirm in this study if this was a result of co-evolution
of host plants with endophytes, many studies have observed
similar trends and the hypothesis remained strong as postulated
by [8]. We also observed that the number of endophytes
isolated from each of the four medicinal plants varies. We did
not vary or increase the sampling size as typically, beneficial
endophytes can be recovered from few plant samples irrespective
of seasonal change [35]. Several factors may influence
endophyte distribution and colonization frequency, with rainfall
and age of host plant as the two most common factors.
Rainfall enhances endophyte dispersal and colonization [22],
while older plants have larger organs to host more endophytes
[23]. We do not rule out the possible influence of these two factors
although we did not ascertain the age of the four plants
sampled nor measured the rainfall. In addition the distinct
numbers of endophytes residing in leaf and stem tissues
observed in P. bleo, M. koenigii, C. citratus and O. diffusa
was consistent with observations in other important medicinal
plants where frequency of endophytes was highest in leaves,
followed by stems and roots [24]. Leaves are generally preferred
by endophytes as leaves have greater surface area [23],
is nutrient-rich and thin-walled to allow endophytic colonization
[25]. These factors coincide with the nature of leaves