Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2021
Authors
Spiridoula Athanasiadou C. chylinski B Moeskops D. Michie C Experton Håvard Steinshamn F. Leiber V. MaurerAbstract
No abstract has been registered
Authors
Klaus. R Westphal Simone Bachleitner Manja M. Severinsen Mathias L. Brundtø Frederik T. Hansen Trine Sørensen Rasmus D. Wollenberg Erik Lysøe Lena Studt Jens L. Sørensen Teis E. Sondergaard Reinhard WimmerAbstract
The plant pathogenic fungus Fusarium graminearum is known to produce a wide array of secondary metabolites during plant infection. This includes several nonribosomal peptides. Recently, the fusaoctaxin (NRPS5/9) and gramilin (NRPS8) gene clusters were shown to be induced by host interactions. To widen our understanding of this important pathogen, we investigated the involvement of the NRPS4 gene cluster during infection and oxidative and osmotic stress. Overexpression of NRPS4 led to the discovery of a new cyclic hexapeptide, fusahexin (1), with the amino acid sequence cyclo-(d-Ala-l-Leu-d-allo-Thr-l-Pro-d-Leu-l-Leu). The structural analyses revealed an unusual ether bond between a proline Cδ to Cβ of the preceding threonine resulting in an oxazine ring system. The comparative genomic analyses showed that the small gene cluster only encodes an ABC transporter in addition to the five-module nonribosomal peptide synthetase (NRPS). Based on the structure of fusahexin and the domain architecture of NRPS4, we propose a biosynthetic model in which the terminal module is used to incorporate two leucine units. So far, iterative use of NRPS modules has primarily been described for siderophore synthetases, which makes NRPS4 a rare example of a fungal nonsiderophore NRPS with distinct iterative module usage.
Authors
Juliet Ochola Danny Coyne Laura Cortada Solveig Haukeland Margaret Ng'ang'a Ahmed Hassanali Charles Opperman Baldwyn TortoAbstract
Bio-communication occurs when living organisms interact with each other, facilitated by the exchange of signals including visual, auditory, tactile and chemical. The most common form of bio-communication between organisms is mediated by chemical signals, commonly referred to as ‘semiochemicals’, and it involves an emitter releasing the chemical signal that is detected by a receiver leading to a phenotypic response in the latter organism. The quality and quantity of the chemical signal released may be influenced by abiotic and biotic factors. Bio-communication has been reported to occur in both above- and below-ground interactions and it can be exploited for the management of pests, such as cyst nematodes, which are pervasive soil-borne pests that cause significant crop production losses worldwide. Cyst nematode hatching and successful infection of hosts are biological processes that are largely influenced by semiochemicals including hatching stimulators, hatching inhibitors, attractants and repellents. These semiochemicals can be used to disrupt interactions between host plants and cyst nematodes. Advances in RNAi techniques such as host-induced gene silencing to interfere with cyst nematode hatching and host location can also be exploited for development of synthetic resistant host cultivars.
Lecture – Dead wood dynamics in old boreal forests: importance for carbon cycling
Jogeir N. Stokland
Authors
Jogeir N. StoklandAbstract
No abstract has been registered
Authors
Martina Paponov Manya Antonyan Rune Slimestad Ivan PaponovAbstract
The plant hormone jasmonic acid (JA) fine tunes the growth–defense dilemma by inhibiting plant growth and stimulating the accumulation of secondary compounds. We investigated the interactions between JA and phytochrome B signaling on growth and the accumulation of selected secondary metabolites in Hypericum perforatum L., a medically important plant, by spraying plants with methyl jasmonate (MeJA) and by adding far-red (FR) lighting. MeJA inhibited plant growth, decreased fructose concentration, and enhanced the accumulation of most secondary metabolites. FR enhanced plant growth and starch accumulation and did not decrease the accumulation of most secondary metabolites. MeJA and FR acted mostly independently with no observable interactions on plant growth or secondary metabolite levels. The accumulation of different compounds (e.g., hypericin, flavonols, flavan-3-ols, and phenolic acid) in shoots, roots, and root exudates showed different responses to the two treatments. These findings indicate that the relationship between growth and secondary compound accumulation is specific and depends on the classes of compounds and/or their organ location. The combined application of MeJA and FR enhanced the accumulation of most secondary compounds without compromising plant growth. Thus, the negative correlations between biomass and the content of secondary compounds predicted by the growth-defense dilemma were overcome.
Authors
Johannes BreidenbachAbstract
No abstract has been registered
Authors
Yanli Man Marianne Stenrød Chi Wu Marit Almvik Roger Holten Jihong Liu Clarke Shankui Yuan Xiaohu Wu Jun Xu Fengshou Dong Yongquan Zheng Xingang LiuAbstract
Difenoconazole is a widely used triazole fungicide that has been frequently detected in the environment, but comprehensive study about its environmental fate and toxicity of potential transformation products (TPs) is still lacking. Here, laboratory experiments were conducted to investigate the degradation kinetics, pathways, and toxicity of transformation products of difenoconazole. 12, 4 and 4 TPs generated by photolysis, hydrolysis and soil degradation were identified via UHPLC-QTOF/MS and the UNIFI software. Four intermediates TP295, TP295A, TP354A and TP387A reported for the first time were confirmed by purchase or synthesis of their standards, and they were further quantified using UHPLC-MS/MS in all tested samples. The main transformation reactions observed for difenoconazole were oxidation, dechlorination and hydroxylation in the environment. ECOSAR prediction and laboratory tests showed that the acute toxicities of four novel TPs on Brachydanio rerio, Daphnia magna and Selenastrum capricornutum are substantially lower than that of difenoconazole, while all the TPs except for TP277C were predicted chronically very toxic to fish, which may pose a potential threat to aquatic ecosystems. The results are important for elucidating the environmental fate of difenoconazole and assessing the environmental risks, and further provide guidance for scientific and reasonable use.
Authors
El Houssein Chouaib HarikAbstract
One of the goals in adopting more sustainable agricultural practices is to reduce green-house-gas emissions from current practices by replacing fossil-fuel-based heavy machinery with lighter, electrical ones. In a not-so-distant scenario where a single farmer owns a fleet of small electrical tractors/robots that can operate in an autonomous/semi-autonomous manner, this will bring along some logistic challenges. It will be highly impractical that the farmer follows each time a given vehicle moves to the charging point to manually charge it. We present in this paper the design and implementation of an autonomous charging station to be used for that purpose. The charging station is a combination of a holonomic mobile platform and a collaborative robotic arm. Vision-based navigation and detection are used in order to plug the power cable from the wall-plug to the vehicle and back to the wall-plug again when the vehicle has recharged its batteries or reached the required level to pursue its tasks in the field. A decision-tree-based scheme is used in order to define the necessary pick, navigate, and plug sequences to fulfill the charging task. Communication between the autonomous charging station and the vehicle is established in order to make the whole process completely autonomous without any manual intervention. We present in this paper the charging station, the docking mechanism, communication scheme, and the deployed algorithms to achieve the autonomous charging process for agricultural electrical vehicles. We also present real experiments performed using the developed platform on an electrical robot-tractor.
Abstract
In developing countries, over 50% of horticultural crops are lost after harvesting due to absense of or poor postharvest cold storage facilities. Cold storage facility is a critical component of the food supply chain and food security because it can extend the storage period of the perishable products; avoid glut and post-harvest losses, reducing transport bottlenecks. The objective of the study was to design and construct an evaporative cooling system to store horticultural products in a wide range of climatic conditions in Ethiopia. The design integrates direct evaporative cooling system and indirect evaporative cooling system with technical improvements and re-arrangements for continuous operation and handling purpose. After the design and construction work of the cooler was completed, its performance was tested and evaluated without product load at maximum mean annual temperature for five days. Finally, the performance and effect of the cooler on tomato shelf life and quality was evaluated by storing fresh tomatoes inside the cooler shelves. For comparison (control group), randomly selected fresh tomatoes were stored in a basket, which is a standard method that retailer display tomatoes in the market in the study area. A portable evaporative cooler was constructed from locally available and used materials and integrated with new temperature and relative humidity sensors. It had a capacity of 260 Kg (573.2 lb). The evaporative cooler resulted in a reduction in the maximum ambient temperature from 32.8°C (91.6°F) to 23.5°C (74.3°F) in the cooler. As the ambient temperature drops to 21.8°C (71.4°F), the temperature in the cooler reduced to 15°C (59°F). The cooler stabilized the relative humidity between 77- 88%. The newly designed and constructed evaporative cooler reduced the postharvest loss of tomato from 80 % in a traditional basket to 5% in the evaporative cooler. The cooler reduced the postharvest loss of tomato by 94%. It maintained the quality of the fresh tomatoes. In conclusion what we showed in this study was that we have refined the design and constructed a low cost and effective cooling system that can be used by poor retailers of vegetables and fruits. Evaporative cooler is an old and forgotten technology, if the design and construction are refined, it can be used to regulate temperature and relative humidity and used in different purposes especially for those who cannot afford to buy modern thermal regulation technologies.
Abstract
No abstract has been registered