Diversity, distribution, and abundance of native Trichoderma species in selected irrigated lowland rice agroecosystems of Tanzania

Aim: The genus Trichoderma is recognized for its potential biocontrol, plant biostimulant, and biofertilizer abilities. This study assessed the diversity and ecological distribution of native Trichoderma species isolated from lowland irrigated rice agroecosystems within six agroecological zones of Tanzania. Methodology and Results : Isolates were obtained from rhizospheric soils using a serial dilution technique. The isolates were assessed for colony color, growth pattern, conidiophore characteristics, phialide, and conidial morphology. DNA was extracted using the CTAB method, and PCR amplification was performed using ITS1F (5'-TCCGTAGGTGAACCTGCGG-3′) and ITS4R (5′-TCCTCCGCTTATTGATATGC-3′). The sequences were compared in the BLASTn program in the National Center for Biotechnology Information (NCBI). Phylogenetic trees provided species resolution, with four main clades: Harzianum ( T. harzianum and T. pleuroti ); Longibrachiatum ( T. longibrachiatum ); Virens ( T. virens ); and Viridae ( T. atroviride, T. asperellum, T. erinaceum, T. koningiopsis, and T. paraviridescens ). The coastal zone had the highest species diversity and evenness (H’=1.21, J=0.88), while the Southern and western highlands zone was completely dominated by a single species (H’=0, J=0). High genetic similarity of 100% was in the Southern and western highlands zone, and the greatest genetic differentiation between the semi-arid and Central plateaux zones was 93%. Soil texture (Clay, Sandy clay to Sandy clay loam), pH (3.36 to 7.31), organic matter (1.07 to 3.18 %), and electrical conductivity (2.5 to 4.58 ds/m) influenced the assemblage of the Trichoderma community within the zones. Conclusion, significance and impact of study: The findings highlight the importance of local environmental conditions in shaping microbial communities and suggest that native Trichoderma isolates could be exploited as biocontrol agents.