Molecular characterization of Morogoro maize-associated virus, a nucleorhabdovirus detected in maize (Zea mays) in Tanzania.

RNAtag-seq of maize samples collected in Tanzania revealed the presence of a previously undescribed nucleorhabdovirus, tentatively named "Morogoro maize-associated virus" (MMaV), in three samples. The MMaV genome is 12,185-12,187 nucleotides long and shares a 69-70% nucleotide sequence identity with taro vein chlorosis virus. Annotation of the genomes showed a typical nucleorhabdovirus gene organization.

Diversity and distribution of Maize-associated totivirus strains from Tanzania.

Typically associated with fungal species, members of the viral family Totiviridae have recently been shown to be associated with plants, including important crop species, such as Carica papaya (papaya) and Zea mays (maize). Maize-associated totivirus (MATV) was first described in China and more recently in Ecuador, where it has been found to co-occur with other viruses known to elicit maize lethal necrosis disease (MLND). In a survey for maize-associated viruses, 35 samples were selected for Illumina HiSeq sequencing, from the Tanzanian maize producing regions of Mara, Arusha, Manyara, Kilimanjaro, Morogoro and Pwani.

Draft Genome Assemblages of 10 Xanthomonas vasicola pv. zeae Strains, Pathogens Causing Leaf Streak Disease of Maize in South Africa.

Maize bacterial leaf streak disease has spread across maize crops in South Africa and therefore potentially poses a threat to maize production and food security. Until recently, this pathogen was identified as a pathovar, whereas our South African genomes seem to be more divergent and create their own subclade.

Alternaria toxins in South African sunflower seeds: cooperative study.

Sunflower seed samples (N = 80) from different sunflower cultivars originating from different localities in South Africa were analyzed for 15 toxins produced by fungi of the genus Alternaria by means of a simple one-step extraction dilute-and-shoot HPLC-MS/MS approach. References for valine-tenuazonic acid (Val-TeA), altenusin (ALTS), and altenuisol (ALTSOH) were isolated from fungal culture extracts and spectroscopically characterized. Additionally, valine-tenuazonic acid was tested regarding its cytotoxicity in comparison with tenuazonic acid (TeA) and showed less activity on HT-29 cells.

A new approach using micro HPLC-MS/MS for multi-mycotoxin analysis in maize samples.

Using micro high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) a simple and fast method for the quantitative determination of 26 mycotoxins was developed. Sample preparation consists of a single extraction step and a dilute-and-shoot approach without further cleanup. With a total run time of 9 min and solvent consumption below 0.

Studies towards optimising the isolation of diplonine, a neurotoxin isolated from cultures of Stenocarpella maydis (Berk.) Sacc.

Diplonine, a mycotoxin that induces neurotoxic clinical signs in the guinea pig, resembling those occurring in cattle and sheep with diplodiosis, was isolated previously from a Stenocarpella maydisculture. Knowledge of the chemical properties of the toxin, which was characterised as a substituted ß-cyclopropylamino acid, enabled amendments in the present study to the initial steps of the isolation procedure. Extraction with water and fractionation by cation exchange chromatography improved the efficiency of isolation, potentially allowing the preparation of larger amounts of the toxin.

Diplonine, a neurotoxin isolated from cultures of the fungus Stenocarpella maydis (Berk.) Sacc. that induces diplodiosis.

Diplodiosis is a neuromycotoxicosis of cattle and sheep caused by ingestion of maize infected with the ear-rot fungus Stenocarpella (= Diplodia ) maydis . Apart from ataxia, paresis, and paralysis, the toxin is responsible for stillbirths and neonatal losses characterized by the presence of spongiform degeneration in the white matter of the brain in the offspring of dams exposed to infected maize cobs. In the present study a toxin, named diplonine, which induced neurological signs in guinea pigs resembling some of those occurring in cattle and sheep, was isolated from S.

Reconstructing the history of maize streak virus strain a dispersal to reveal diversification hot spots and its origin in southern Africa.

Maize streak virus strain A (MSV-A), the causal agent of maize streak disease, is today one of the most serious biotic threats to African food security. Determining where MSV-A originated and how it spread transcontinentally could yield valuable insights into its historical emergence as a crop pathogen. Similarly, determining where the major extant MSV-A lineages arose could identify geographical hot spots of MSV evolution.

Dating the origins of the maize-adapted strain of maize streak virus, MSV-A.

Maize streak virus (MSV), which causes maize streak disease (MSD), is one of the most serious biotic threats to African food security. Here, we use whole MSV genomes sampled over 30 years to estimate the dates of key evolutionary events in the 500 year association of MSV and maize. The substitution rates implied by our analyses agree closely with those estimated previously in controlled MSV evolution experiments, and we use them to infer the date when the maize-adapted strain, MSV-A, was generated by recombination between two grass-adapted MSV strains.