Molecular characterization of a fungal aldehyde dehydrogenase in the Tricholoma vaccinumspruce ectomycorrhiza

Understanding of ectomycorrhiza functioning has been slowed down by less investigations of this symbiotic association at the molecular level. In this study, the possible role of a specific fungal aldehyde dehydrogenase (ALDH) in the host-specific mutual symbiosis between the basidiomycete fungus Tricholoma vaccinum and its compatible host plant spruce (Picea abies) was investigated. Also, the involvement of indole-3-acetic acid (IAA) in ectomycorrhiza formation, which has been controversially observed and discussed in literature, was investigated in detail. As a first step, the ectomycorrhiza-specifically expressed gene ald1 was isolated from T. vaccinum. Sequence analysis showed that the ORF of ald1 is interrupted by 16 introns. The conceptually translated protein, Ald1, of 502 amino acids with a predicted molecular mass of 53 kDa was subsequently confirmed by Western blotting. An alignment of Ald1 with other 53 specific fungal ALDHs, representing all major phyla in the kingdom of fungi, was used to reinvestigate the evolutionary relationships in this enzyme family. The phylogenetic reconstruction, under Bayesian inference, revealed that, with the exception of chytridiomycota, fungal ALDHs, which clustered in distinct taxonomic groups in the phylogram, underwent two major duplication events during evolution resulting in multiple ALDH paralogs, with specifically high number of paralogs in higher fungi. Stress Response Elements (STREs) were observed in the promoter region of ald1, suggesting a possible role of stress induction for this gene. This prompted us to investigate the possible aldehyde- and alcohol-mediated stress induction of ald1 expression by real time RT-PCR, which revealed significantly increased gene expression upon addition of 0.1 mM indole-3-acetaldehyde (IAAld), 0.1 mM benzaldehyde or 0.01% ethanol. Furthermore, heterologous expression of ald1 in Escherichia coli and subsequent in vitro enzyme activity assay demonstrated the oxidation of various aldehydes with different kinetics using both NAD+ and NADP+ as cofactors. In order to understand the biological function of this gene in T. vaccinum, it was overexpressed in the fungus using Agrobacterium tumefaciens-mediated transformation (ATMT). Functional analysis showed that Ald1-overproducing transformants significantly reduced ethanol stress. These results unequivocally demonstrated the ability of Ald1 to circumvent ethanol stress, a critical function in ectomycorrhizal habitats. In addition, the induction of ald1 expression by IAAld suggests that the gene might be involved, at least partly, in production of indole-3-acetic acid (IAA)

Role of the cyclic lipopeptide massetolide A in biological control of Phytophthora infestans and in colonization of tomato plants by Pseudomonas fluorescens

Pseudomonas strains have shown promising results in biological control of late blight caused by Phytophthora infestans. However, the mechanism(s) and metabolites involved are in many cases poorly understood. Here, the role of the cyclic lipopeptide massetolide A of Pseudomonas fluorescens SS101 in biocontrol of tomato late blight was examined. Pseudomonas fluorescens SS101 was effective in preventing infection of tomato (Lycopersicon esculentum) leaves by P. infestans and significantly reduced the expansion of existing late blight lesions. Massetolide A was an important component of the activity of P. fluorescens SS101, since the massA-mutant was significantly less effective in biocontrol, and purified massetolide A provided significant control of P. infestans, both locally and systemically via induced resistance. Assays with nahG transgenic plants indicated that the systemic resistance response induced by SS101 or massetolide A was independent of salicylic acid signalling. Strain SS101 colonized the roots of tomato seedlings significantly better than its massA-mutant, indicating that massetolide A was an important trait in plant colonization. This study shows that the cyclic lipopeptide surfactant massetolide A is a metabolite with versatile functions in the ecology of P fluorescens SS101 and in interactions with tomato plants and the late blight pathogen P. infestans

Assessment of Maize Lethal Necrosis (MLN) prevalence and its impact on maize production in Rwanda

Maize lethal necrosis (MLN) is a serious viral disease of maize, which was first reported in Rwanda in 2013. Being aware of the disastrous effects it had caused in regional countries, we set out to study its prevalence, level of awareness among farmers on management practices and its impact on the overall maize production and farmer livelihoods during 2015. This country wide study targeted a total of 539 respondents drawn from all the 30 districts, down to each sector. We used stratified, purposive and random sampling to collect data. Our results indicated a wide spread of disease to the entire country. We ran cumulative logistic regression models and found out that the chances of having higher levels of MLN in Western Province, for example, are ten, three, one and one times the chances in the Eastern Province, Kigali, Northern Province and Southern Province, respectively. Results also showed that a significantly higher number of respondents (54.4%) were not aware of MLN, which is a concern for its management. The assessment of MLN impact on maize production indicated that the disease had caused losses of up to 100% and was threatening the production of this food security crop. The observed low levels of MLN awareness as well as inappropriate plant protection measures calls for stepping up of MLN awareness and management campaigns among the farming community to curtail its further spread.Keywords: Maize lethal necrosis, Rwanda, prevalence, impac

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Phenotypic diversity analysis of sweetpotato for breeding dual-purpose varieties

The genetic diversity available in sweetpotato has not been explored to develop dual-purpose sweetpotato varieties (DPSVs). The objectives of this study were to assess the level of phenotypic diversity present among sweetpotato varieties grown in Rwanda, and to select suitable parents for breeding DPSVs. Fifty-one diverse sweetpotato genotypes were evaluated in field trials conducted at the Rubona and Karama experimental stations of the Rwanda Agriculture Board using a 6 × 9 unbalanced alpha lattice design with three replications. Genotypes and sites showed significant interaction (P < .05), indicating differential response of genotypes in fresh root yield (FRY), root dry matter content, dry root yield (DRY), marketable root number, marketable root weight, flowering frequency and harvest index. The top two genotypes selected for their high FRY were RW11-4923 (20.9 t ha−1) and RW11-2419 (20.18 t ha−1). RW11-4923 and Wagabolige were the best performers for vine yield, producing 23.67 and 23.45 t ha−1 of vines, respectively. Ukerewe performed well for its DRY (7.09 t ha−1), while RW11-4923 had the highest mean dry vine yield (5.17 t ha−1). RW11-2910 and 8-1038 had root-to-vine ratios of 2.0 and 1.5, respectively, suggesting their suitability as breeding parents, to breed DPSVs. Two main phenotypic groups with 10 sub-groups were detected through cluster analysis. Principal component analysis showed that the first four components accounted for 76.33% of the phenotypic variation present among the 51 genotypes. The selected sweetpotato genotypes that had a combination of high storage root yields and heavy vine production should be used as parents in developing DPSVs, concurrently incorporating farmer-preferred traits

Interaction of genotype and environment effects on important traits of cassava (Manihot esculenta Crantz)

General and specific environmental adaptation of genotypes is the main goal of breeders. However, genotype-by-environment (G × E) interaction complicates the identification of genotypes for release. This study aimed at analyzing the effects of G × E interaction on the expression of important cassava traits using two multivariate analyses: additive main effects and multiplicative interaction (AMMI) and genotype stability index (GSI). Total carotene content (TCC), postharvest physiological deterioration (PPD), and reaction to viral diseases were significantly affected by G × E interaction effects. The low percent (%) variation due to genotype for cassava brown streak disease (CBSD) explained the influence of environment on CBSD expression. The % variation due to genotype for TCC was higher (96%) than variation due to environment (1.7%) and G × E interaction (2.4%) indicating a low interaction effect of environment on TCC accumulation. The % variation due to genotype was higher than % variation due to environment for all traits but CBSD root necrosis and CBSD on stems, indicating the influence of environment on the severity of the viral diseases. These findings indicate that screening for disease resistance requires multi-environment trials, whereas a single-environment trial suffices to screen for total carotene content