The diversity of culturable endophytic actinomycetes associated with wild Compositae plants is scantily explored. In this study, one hundred
and thirty one endophytic actinobacteria were isolated from ten Compositae plant species collected from South Sinai in Egypt. Microscopic and
chemotaxonomic investigation of the isolates indicated fourteen genera. Rare genera, such as Microtetraspora, and Intrasporangium, which have
never been previously reported to be endophytic, were identified. Each plant species accommodated between three to eight genera of actinobacteria
and unidentified strains were recovered from seven plant species.
The generic diversity analysis of endophytic assemblages grouped the plant species into three main clusters, representing high, moderate and
low endophytic diversity. The endophytes showed high functional diversity, based on forty four catabolic and plant growth promotion traits;
providing some evidence that such traits could represent key criteria for successful residence of endophytes in the endosphere. Stress-tolerance
traits were more predictive measure of functional diversity differences between the endophyte assemblages (Shannon’s index, p ¼ 0.01). The
results indicate a potential prominent role of endophytes for their hosts and emphasize the potency of plant endosphere as a habitat for actinobacteria
with promising future applications