Transcriptome analysis and systemic RNAi response in the African sweetpotato weevil (Cylas puncticollis, Coleoptera, Brentidae

<div><p>The African sweetpotato weevil (SPW) <i>Cylas puncticollis</i> Boheman is one of the most important constraints of sweetpotato production in Sub-Saharan Africa and yet is largely an uncharacterized insect pest. Here, we report on the transcriptome analysis of SPW generated using an Illumina platform. More than 213 million sequencing reads were obtained and assembled into 89,599 contigs. This assembly was followed by a gene ontology annotation. Subsequently, a transcriptome search showed that the necessary RNAi components relevant to the three major RNAi pathways, were found to be expressed in SPW. To address the functionality of the RNAi mechanism in this species, dsRNA was injected into second instar larvae targeting <i>laccase2</i>, a gene which encodes an enzyme involved in the sclerotization of insect exoskeleton. The body of treated insects showed inhibition of sclerotization, leading eventually to death. Quantitative Real Time PCR (qPCR) confirmed this phenotype to be the result of gene silencing. Together, our results provide valuable sequence data on this important insect pest and demonstrate that a functional RNAi pathway with a strong and systemic effect is present in SPW and can further be explored as a new strategy for controlling this important pest.</p></div

Biosafety capacity building: Experiences and challenges of a distance learning approach

Biotechnology is revolutionizing industrial and agricultural practice as the number of commercial biotechnology products is increasing each year. Simultaneously, a number of regulatory approaches are put into place to allow technological advancement while preserving public health and the environment. Developing and/or emerging countries often face major barriers to access biotechnologies and biotechnology-derived products as they frequently lack the institutional capacities and professional competence in exercising regulatory oversight. In order to address this need, intensive biosafety capacity building is required. Different training approaches can be used to train individuals in biosafety ranging from long-term leading to an academically accredited postgraduate certificate or a First Level Masters degree, to short term courses. In this work, we illustrate the applicability of a different approach to biosafety capacity building based on a distance e-learning system, the UNIDO e-Biosafety program that has been annually organized at the Marche Polytechnic University (MPU) in Italy and Ghent University (UGent) in Belgium since 2006. Even though there are some challenges, we can conclude based on our experience that distance learning in combination with on-campus tuition is amendable for biosafety capacity building

RNAi-based gene silencing through dsRNA injection or ingestion against the African sweet potato weevil Cylas puncticollis (Coleoptera: Brentidae).

BACKGROUND. RNA interference (RNAi) technology can potentially serve as a suitable strategy to control the African sweet potato weevil Cylas puncticollis (SPW), which is a critical pest in sub-Saharan Africa. Important prerequisites are required to use RNAi in pest control, such as the presence of an efficient RNAi response and the identification of suitable target genes. RESULTS. Here we evaluated the toxicity of dsRNAs targeting essential genes by injection and oral feeding in SPW. In injection assays, 12 of 24 dsRNAs were as toxic as the one targeting Snf7, a gene used commercially against Diabrotica virgifera virgifera. Three dsRNAs with high insecticidal activity were then chosen for oral feeding experiments. The data confirmed that oral delivery can elicit a significant toxicity, albeit lower compared with injection. Subsequently, ex vivo assays revealed that dsRNA is affected by degradation in the SPW digestive system, possibly explaining the lower RNAi effect by oral ingestion. CONCLUSION. We conclude that the full potential of RNAi in SPW is affected by the presence of nucleases. Therefore, for future application in crop protection, it is necessary constantly to provide new dsRNA and/or protect it against possible degradation in order to obtain a higher RNAi efficacy

DTREEv2, a computer-based support system for the risk assessment of genetically modified plants

Risk assessment of genetically modified organisms (GMOs) remains a contentious area and a major factor influencing the adoption of agricultural biotech. Methodologically, in many countries, risk assessment is conducted by expert committees with little or no recourse to databases and expert systems that can facilitate the risk assessment process. In this paper we describe DTREEv2, a computer-based decision support system for the identification of hazards related to the introduction of GM-crops into the environment. DTREEv2 structures hazard identification and evaluation by means of an Event-Tree type of analysis. The system produces an output flagging identified hazards and potential risks. It is intended to be used for the preparation and evaluation of biosafety dossiers and, as such, its usefulness extends to researchers, risk assessors and regulators in government and industry

Fine‐scale spatial genetic structure, mating, and gene dispersal patterns in Parkia biglobosa

Premise: A good understanding of genetic variation and gene dispersal in tree populations is crucial for their sustainable management, particularly in a context of rapid environmental changes. West African Sudanian savannahs are being fragmented and degraded, partly due to expansion of crop cultivation and monocultures that reduce tree density and may impact pollinators. The population dynamics of important indigenous trees could also be affected. We investigated the influence of habitat fragmentation on patterns of genetic diversity and gene dispersal of a key Sudanian agroforestry tree species, Parkia biglobosa. Methods: Using 10 highly polymorphic nuclear microsatellites, we genotyped 2475 samples from reproductive trees, seedlings, and embryos in four tree populations presenting different levels of habitat fragmentation. Results: Parkia biglobosa presented similar high genetic diversity across the four populations studied. Genetic diversity and inbreeding were similar between adults and embryo cohorts. In all four populations, the selfing rate was less than 1%. The effective number of pollen donors per tree was high (NEP~ 18–22), as was the pollen immigration rate (from 34 to 74%). Pollen dispersal was characterized by a fat-tailed distribution with mean estimates exceeding 200 m. In three populations, stem diameter had a pronounced effect on male reproductive success. Here, the highest male reproductive success was observed in trees with a diameter at breast height between 60 and 75 cm. Conclusions: At the scale analyzed, fragmentation does not seem to pose limitations to gene flow in any of the sites investigated, regardless of the landscape configuration associated with the different tree stands. The study provides useful insights on the reproductive biology of an important tree species in the West African savannahs.SCOPUS: ar.jDecretOANoAutActifinfo:eu-repo/semantics/publishe

Rhodococcus fascians impacts plant development through the dynamic Fas-mediated production of a cytokinin mix

The phytopathogenic actinomycete Rhodococcus fascians strain D188 relies on the linear plasmid-encoded fas operon for its virulence. The bacteria secrete six cytokinin bases that synergistically redirect the developmental program of the plant to stimulate proliferation of young shoot tissue, thus establishing a niche. A yeast-based cytokinin bioassay combined with cytokinin profiling of bacterial mutants, revealed that the fas operon is essential for the enhanced production of iP, cZ, tZ, 2MeScZ, and 2MeStZ. The cytokinin metabolite data and the demonstration of the enzymatic activities of FasD (isopentenyltransferase), FasE (cytokinin oxidase/dehydrogenase), and FasF (phosphoribohydrolase), allowed us to propose a pathway for the production of the cytokinin spectrum. Further evaluation of the pathogenicity of different fas mutants, in planta fas gene expression, and cytokinin signal transduction upon infection implied that the secretion of the cytokinin mix is a highly dynamic process with the production of symptom initiation and maintenance waves