The Morphological And Molecular Variability Of Sporisorium Scitamineum Isolates In Eswatini

Abstract

Background: Sugarcane smut, caused by Sporisorium scitamineum, is a disease of economic importance in the sugarcane industry, occasioning losses of up to 50%. Current management practices have been shown to be ineffective in controlling the fungal disease and hence the understanding of the local pathogen and development of appropriate control measures is required. This study investigates the morphology, development patterns and molecular variability of Sporisorium scitamineum isolates in Eswatini to understand its pathogenicity for effective control.Results: Fungal isolates were collected along the Sugarbelt in Lowveld of Eswatini. The isolates were verified by polymerase chain reaction (PCR) using the bE 4 and bE 8 specific primers with an amplification of a 420bp fragment; this was further verified by the sequencing results. The teliospores from the isolates were uniform for the 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 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. Genetic distance matrix analysis and the cluster analysis showed a high homology (99-100%) among the local isolates.Conclusion: There is very low variability in the strains that are found in the selected sugarcane growing areas in Eswatini. Local isolates may possess varying virulence levels, but may not require variable management strategies.

Climate change impacts on sugarcane smut disease and its management

“…The primary infection is caused by soil-borne teliospores or the planting of diseased setts, while secondary infection is caused by air-borne fungal spores infecting a healthy crop that is already standing (Hoy et al, 1991a). Nkhabindze et al (2022) reported that although there were morphological differences in isolates, the genetic variation among isolates for the Internal Transcribed Spacer (ITS) was very low.…”