The antagonistic role of rhizosphere and endophytic fungi from feral and cultivated date palms on wilt causing fungi in Oman
Publication Date
July 27, 2026
Creator
Abstract
Date palm is one of the major crops grown in Oman. Date palm wilt, caused by the soil borne pathogen Ceratocystis radicicola, is a disease that is spreading rapidly. In this study, endophytic and rhizosphere fungi have been isolated from roots and rhizosphere soil of cultivated and feral date palm from different locations. Rhizosphere soil was analysed for minerals, total organic carbon (TOC) and total inorganic carbon (TIC). DNA was extracted from soil and fungal diversity was determined using Illumina MiSeq sequencing. Results showed that fungal diversity between feral and cultivated date palms was not significantly different. However, the fungal diversity was significantly different between locations; for example, Swaiq location 1 showed a unique fungal diversity. A correlation network clustering and a Principal Component Analysis (PCA) was done between Operational Taxonomic Units (OTUs) and soil minerals that showed 13 clusters with clusters 4 and 5 having highest OTUs with feral date palm. The influence of different soil parameters between feral and cultivated systems revealed no outcome on the fungal diversity.
The isolated fungi were tested for antagonistic effect on date palm pathogens Ceratocystis radicicola and Fusarium solani by dual culture. Two fungi showed an antagonistic effect with prominent inhibition zones for both date palm pathogens. The DNA was extracted from the antagonistic fungi and sequenced using ITS1 and ITS4 primers, and were identified as Talaromyces sp. from cultivated date palm roots and Aspergillus terreus from rhizosphere soil of cultivated date palm. In addition, sequencing resulted in identification of 3 new species of Talaromyces. A phylogenetic tree was constructed with ITS sequences and ITS-RPB2 and revealed that the isolates are new species of Talaromyces Section Trachyspermi. This study is the first report of the potential new Talaromyces species. An electrolyte leakage bioassay was carried out on the culture filtrates of the antagonistic fungi where EC and pH of the pathogen was recorded. Aspergillus terreus caused more significant changes than Talaromyces sp.
SEM imaging of the inhibition zones from dual cultures with A. terreus and Talaromyces sp. with the pathogens C. radicicola and F. solani, showed the antagonistic effect, where Talaromyces spp. effected C. radicicola spores by formation of chains or a net-like structure around the spores resulting in their shrinkage. The effect of A. terreus was through its spores clumping on the hyphae of C. radicicola and the hyphae of A. terreus covering the hyphae of C. radicicola causing it to shrivel. For F. solani, Talaromyces spp. spores and hyphae bound to the hyphae of F. solani causing them to shrivel. In contrast, Aspergillus terreus resulted in wrinkled spores and distorted hyphae of F. solani, with evident tissue degradation.
This study showed the potential of investigating the rhizosphere and endophytic fungi of date palms especially the feral palms as an insight on the biodiversity of these micro communities. Also, new biocontrol agents could be detected and investigated on various plant pathogens, using dual culture, SEM imaging and electrolyte leakage to provide further evidence on the efficacy of these isolates.
Item Type
ethesis
Thesis Type
PhD
Supervisors
Subjects (LC)
Associated Schools / Departments
School of Biosciences (UK)
eprints ID
80699
UoN Repository URI
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Raja Al Busaidi 4174028 The Antagonistic Role of Rhizosphere and Endophytic Fungion Wilt Causing Fungi in Oman Final Feb 27.pdf
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