The morphological and molecular characterisations of two lance nematode species isolated from the rhizosphere of banana, Hoplolaimus seinhorsti and H. pararobustus, are provided based on an integrative study that includes light and scanning electron microscopy, phylogenetic analysis and two tree-based molecular species delimitation methods (GMYC and bPTP). Nineteen new sequences were obtained, including 5 partial 18S rRNA, 6 D2-D3 of 28S rRNA, 1 ITS rRNA and 7 COI mtDNA (the first COI sequences of H. seinhorsti and H. pararobustus), and an updated morphological character comparison of 37 Hoplolaimus species is presented. The tree-based molecular species-delimitation approaches employed gave markedly differing results, and also showed remarkable discrepancies among the investigated genes, although the bPTP output was found to agree well with established morphological species delimitations. Both species-delimitation approaches did, however, provide the same output for the COI mtDNA sequences, and the COI mtDNA gene sequence was also found to correspond better to established morphological species. It is therefore recommended by this paper as representing the most suitable barcode marker for Hoplolaimus species identification. This integrative study also resulted in the corrective reassignment of 17 gene sequences that were previously unidentified or incorrectly classified, as well as concluding that H. pararobustus consists of two cryptic species.

Extensive root galling observed on plantain (Musa spp., AAB) in Nigeria was analysed using Nad5 mitochondrial DNA sequences and the causal agent identified as Meloidogyne arenaria. Following the inoculation of population cultured, Koch’s postulates was fulfilled and the same symptoms observed. This provides the first molecular confirmation of M. arenaria causing such damage to plantain and highlighting its potential as a threat to the crop. Root knot nematodes are known to affect banana and plantain production but diagnosis of the species involved is only just being accurately determined with the recent improvements in molecular techniques.

Plantain (Musa spp., AAB), an important staple food in Africa with West Africa accounting for 32% of global production, is prone to numerous pests and diseases of which plant-parasitic nematodes ar...

Introduction: Over 24 million people have been infected globally with the novel coronavirus, SARS-CoV-2, with more than 820,000 succumbing to the resulting COVID-19 disease as of the end of August 2020. The molecular mechanisms underlying the pathogenesis of the disease are not completely elucidated. Thus, we aim to understand host response to SARS-CoV-2 infection by comparing samples collected from two distinct compartments (infection site and blood), obtained from COVID-19 subjects and healthy controls. Methods: We used two publicly available gene expression datasets generated via RNA sequencing in two different samples; nasopharyngeal swabs and peripheral blood mononuclear cells (PBMCs). We performed a differential gene expression analysis between COVID-19 subjects and healthy controls in the two datasets and then functionally profiled their differentially expressed genes (DEGs). The genes involved in innate immunity were also determined. Results: We found a clear difference in the host response to SARS-CoV-2 infection between the two sample groups. In COVID-19 subjects, the nasopharyngeal sample group indicated upregulation of genes involved in cytokine activity and interferon signalling pathway, as well as downregulation of genes involved in oxidative phosphorylation and viral transcription. Host response in COVID-19 subjects for the PBMC group, involved upregulation of genes involved in the complement system and immunoglobulin mediated immune response. CXCL13, GABRE, IFITM3 were upregulated and HSPA1B was downregulated in COVID-19 subjects in both sample groups. Conclusion: Our results indicate the host response to SARS-CoV-2 is compartmentalized and suggests potential biomarkers of response to SARS-CoV-2 infection. Highlights: Transcriptomic profiling from publicly available RNA-seq count data revealed a site-specific immune response in COVID-19. Host response was found cellular-mediated in nasopharyngeal samples and humoral-mediated in PBMCs samples. CXCL13, GABRE and IFITM3 commonly upregulated and HSPA1B downregulated in both sample groups highlights the potential of these molecules as markers of response to SARS-CoV-2 infection.

Radopholus similis is a devastating pest to tropical agriculture, including economically important crops such as banana and citrus. To better understand the diverse biology of R. similis, the genomes of 18 populations from five continents were sequenced and compared to (i) provide a snapshot of the global genetic diversity of R. similis and identify influencers of genetic diversity; (ii) determine whether R. similis populations show evidence of host-specific adaption; (iii) provide insight into the endosymbiotic relationship of R. similis with Wolbachia; and (iv) provide support for the mode of reproduction of R. similis. A whole-genome single-nucleotide polymorphism (SNP) analysis through principal component analysis and a phylogenomic maximum likelihood tree revealed that the largest correlative factors with genetic diversity in these populations were continent and Wolbachia host status. Both methods demonstrated that the greatest genetic diversity of R. similis is in Africa and Asia. Genetically isolated populations from Colombia and Australia were identified using SNP-based phylogeny and Weir and Cockerham's F _ST as potential recent introductions from Africa. Additionally, 186 unique SNPs, including in 12 potential effectors genes, were associated with R. similis populations originating from non-banana hosts and warrant further investigation, with particular in relation to how R. similis differentiates hosts. Four genes potentially associated with the ability of R. similis to host Wolbachia would also warrant further research. Overall, this work provides substantial genomic resources to the nematology community and foundational genomic and population information on an economically important and understudied plant-pathogenic nematode pest. [ ] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2026.

This study evaluated macropropagated plantlets for nematode resistance screening in Musa spp. We aimed to determine the optimal timing for assessing resistance to Radopholus similis and Meloidogyne arenaria in the plantain cultivar ‘Agbagba’ at 30-, 60-, and 90-days post-inoculation (DPI). Additionally, we tested different substrates for early-stage screening at 7 DPI. Results indicated that 60 DPI is optimal for resistance screening against R. similis due to significant root damage, while M. arenaria reproduction peaked at 90 DPI without extensive root deterioration. The sand-absorbent polymer (SAP) substrate was most effective for early nematode penetration. Using these findings, we assessed five Musa genotypes at 60 DPI; ‘SH 3142’ and ‘Pisang Jari Buaya’ showed resistance to R. similis, ‘Agbagba’ was susceptible, ‘Yangambi KM5’ was unexpectedly susceptible, and ‘Pisang Lilin’ showed intermediate resistance. This study highlights that macropropagated plantlets can be used as an effective method for rapid preliminary resistance screening in Musa spp.