_____________________________________________________________________________________________________ *Corresponding author: E-mail: nkechi.iyanyi@gmail.com; Journal of Advances in Microbiology 22(4): 25-36, 2022; Article no.JAMB.84702 ISSN: 2456-7116 Mycobiota of Cnidoscolus aconitifolius (Mill.) Phyllosphere N. G. Ogbuji a,b* and A. E. Ataga a,b a Department of Plant Science and Biotechnology, University of Port Harcourt, Port Harcourt, Nigeria. b Regional Center for Biotechnology and Bio-resources Research, University of Port Harcourt, Port Harcourt, Nigeria. Authors’ contributions This work was carried out in collaboration between both authors. Both authors read and approved the final manuscript. Article Information DOI: 10.9734/JAMB/2022/v22i430454 Open Peer Review History: This journal follows the Advanced Open Peer Review policy. Identity of the Reviewers, Editor(s) and additional Reviewers, peer review comments, different versions of the manuscript, comments of the editors, etc are available here: https://www.sdiarticle5.com/review-history/84702 Received 15 January 2022 Accepted 19 March 2022 Published 08 April 2022 ABSTRACT Aims: This study was conducted to determine the mycobiota of Cnidoscolus aconitifolius phyllosphere using metagenomics. The phyllosphere, which is the above-ground (aerial) part of plants, is colonized by different microorganisms some of which may be pathogenic to plants and also to humans and animals. Methodology: The mycobiota was determined by sequencing the 18S rRNA gene on Illumina MiSeq platform. The primer pair: ITS1F (5´-CTTGGTCATTTAGAGGAAGTAAT-3´) and ITS4 (5´- TCCTCCGCTTATTGACATGS-3´) were used to target the ITS regions I and II, and a portion of 28S rDNA. Results: A total of 107 Operational Taxonomic Units (OTUs) were obtained. The mycobiota of C. aconitifolius had 100% Ascomycota classified into Dothideomycetes (84.15%), Eurotiomycetes (2.26%) and Sordariomycetes (12.45%). Only 1.13% of the fungi were unassigned at the class level. The core mycobiota of chaya consisted of the genera Cladosporium (51.70%), Lasiodiplodia (18.11%), Allophoma (6.79%), Stagonosporosis (2.26%) and Aspergillus (2.26%). Conclusion: The economic importance of the organisms obtained were highlighted. The result from this study shows that C. aconitifolius phyllosphere harbors diverse fungi some of which may promote plant growth or are pathogenic to plants and/or humans. Original Research Article