Search

Sweetpotato (Ipomoea batatas L.) is an essential food crop globally, especially for farmers facing resource limitations. Like other crops, sweetpotato cultivation faces significant production challenges due to viral infections. This study aimed to identify and characterize viruses affecting sweetpotato crops in Uganda, mostly those associated with sweetpotato virus disease (SPVD). Infected leaf samples were collected from farmers' fields in multiple districts spanning three regions in Uganda. MiSeq, a next-generation sequencing platform, was used to generate reads from the viral nucleic acid. The results revealed nine viruses infecting sweetpotato crops in Uganda, with most plants infected by multiple viral species. Sweet potato pakakuy and sweet potato symptomless virus_1 are reported in Uganda for the first time. Phylogenetic analyses demonstrated that some viruses have evolved to form new phylogroups, likely due to high mutations and recombination, particularly in the coat protein, P1 protein, cylindrical inclusion, and helper component proteinase regions of the potyvirus. The sweet potato virus C carried more codons under positive diversifying selection than the closely related sweet potato feathery mottle virus, particularly in the P1 gene. This study provides valuable insights into the viral species infecting sweetpotato crops, infection severity, and the evolution of sweet potato viruses in Uganda. [ABSTRACT FROM AUTHOR]

Equine histoplasmosis commonly known as epizootic lymphangitis (EL) is a neglected granulomatous disease of equine that is endemic to Ethiopia. It is caused by Histoplasma capsulatum variety farciminosum, a dimorphic fungus that is closely related to H. capsulatum variety capsulatum. The objective of this study was to undertake a phylogenetic analysis of H. capsulatum isolated from EL cases of horses in central Ethiopia and evaluate their relationship with H. capsulatum isolates in other countries and/or clades using the internal transcribed spacer (ITS) region of rRNA genes. Clinical and mycological examinations, DNA extraction, polymerase chain reaction (PCR), Sanger sequencing, and phylogenetic analysis were used for undertaking this study. Additionally, sequence data of Histoplasma isolates were retrieved from GenBank and included for a comprehensive phylogenetic analysis. A total of 390 horses were screened for EL and 97 were positive clinically while H. capsulatum was isolated from 60 horses and further confirmed with PCR, of which 54 were sequenced. BLAST analysis of these 54 isolates identified 29 H. capsulatum isolates and 14 isolates from other fungal genera while the remaining 11 samples were deemed insufficient for further downstream analysis. The phylogenetic analysis identified five clades, namely, African, Eurasian, North American 1 and 2, and Latin American A and B. The Ethiopian isolates were closely aggregated with isolates of the Latin American A and Eurasian clades, whereas being distantly related to isolates from North American 1 and 2 clades as well as Latin American B clade. This study highlights the possible origins and transmission routes of Histoplasmosis in Ethiopia. [ABSTRACT FROM AUTHOR]

Sustainable control of plant diseases requires a good understanding of the epidemiological aspects such as the biology of the causal pathogens. In the current study, we used RT-PCR and Next Generation Sequencing (NGS) to contribute to the characterization of maize lethal necrotic (MLN) viruses and to identify other possible viruses that could represent a future threat in maize production in Tanzania. RT-PCR screening for Maize Chlorotic Mottle Virus (MCMV) detected the virus in the majority (97%) of the samples (n = 223). Analysis of a subset (n = 48) of the samples using NGS-Illumina Miseq detected MCMV and Sugarcane Mosaic Virus (SCMV) at a co-infection of 62%. The analysis further detected Maize streak virus with an 8% incidence in samples where MCMV and SCMV were also detected. In addition, signatures of Maize dwarf mosaic virus, Sorghum mosaic virus, Maize yellow dwarf virus-RMV and Barley yellow dwarf virus were detected with low coverage. Phylogenetic analysis of the viral coat protein showed that isolates of MCMV and SCMV were similar to those previously reported in East Africa and Hebei, China. Besides characterization, we used farmers' interviews and direct field observations to give insights into MLN status in different agro-ecological zones (AEZs) in Kilimanjaro, Mayara, and Arusha. Through the survey, we showed that the prevalence of MLN differed across regions (P = 0.0012) and villages (P < 0.0001) but not across AEZs (P > 0.05). The study shows changing MLN dynamics in Tanzania and emphasizes the need for regional scientists to utilize farmers' awareness in managing the disease. [ABSTRACT FROM AUTHOR]