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The morphological and molecular variability of Sporisorium scitamineum isolates from Eswatini

2022; Southern Cross Publishing; Issue: 16(11):2022 Linguagem: Inglês

10.21475/ajcs.22.16.11.p3769

1835-2693

Bongani Z. Nkhabindze, Diana M. Earnshaw, Elijah Ateka, Harrison Wanyika,

Plant Pathogenic Bacteria Studies

Sugarcane smut is a disease of economic importance in the sugarcane industry, occasioning losses of up to 50%. Current management practices have been ineffective in controlling the fungal disease, and hence the understanding of the pathogen and the development of appropriate control measures are required. This study investigates the morphology, virulence and molecular variability of Sporisorium scitamineum isolates from Eswatini to understand its pathogenicity for effective control. Fungal isolates were collected along the Sugarbelt in the Lowveld of Eswatini. The isolates were verified by polymerase chain reaction using the bE4 and bE8 specific primers with amplification of a 459bp fragment. The identity was further verified by DNA sequencing. The teliospores from the isolates were uniform in brown colour, spiny texture and circular shape. The teliospore sizes were significantly (P=0.05) different among the isolates. The isolate from Big-Bend had a mean spore diameter of 5.55µm, while Simunye, Nsoko and Mhlume had average diameters of 4.69µm, 4.98µm and 4.87µm, respectively. The documentation of the developmental stages revealed that the samples were of variable virulence with significantly (P=0.05) different rates of promycelium development. The variable virulence of the isolates was further confirmed by the in-vivo pathogen biomass quantification by RT-qPCR. Genetic distance matrix analysis and cluster analysis showed high homology (99-100%) among the local isolates which indicate that there is a low variability among the strains that are found in the selected sugarcane growing areas of Eswatini