Carlsberg Laboratory

Dormancy is a characteristic of plant seeds that has evolved to avoid exposing the young seedling to adverse weather conditions. The mitogen-activated protein kinase MKK3 from barley is known to mediate the duration of dormancy and subsequent germination of the grain. Here, we used computational and phylogenetic approaches to define the structural model of the monomeric MKK3 domain in complex with the downstream MAPK protein kinase that it phosphorylates. We utilized key genetic variants of the barley MKK3 and generated the structural MKK3/MAPK enzyme-substrate complex, supported by evolutionary analyses, to rationalize the effects of the MKK3 variants occurring at the ATP binding site and in the loops that can be phosphorylated. We propose the likely mechanism of ATP hydrolysis and the effects of common genetic variants on MKK3 activity, thereby influencing the duration of dormancy. The data will facilitate future manipulations of dormancy length in different environments.

Abstract BackgroundIn breeding the aim is to identify and accumulate beneficial variants. However, detection of these variants may be challenging in the presence of extensive genotype x environment interactions (GxE), as variant effects will be conditional on environment.MethodsThe study assesses the performance of264diploid perennial ryegrass accessions in a multi-environment field trial. We investigate the extent of GxE, for yield (total dry matter) and persistence traits, i.e. winter kill and spring cover, under environmental conditions experienced in Nordic and Baltic regions at the limit of the species distribution. Two different approaches to modelling GxE were tested: reaction norm and envirotyping, and the models were validated under three different breeding scenarios.ResultsOur analysis documented the presence of significant GxE interaction for all traits investigated in the study. Validation showed improvements in prediction accuracy when accounting for GxE: up to 4% for yield when predicting in unobserved environments, and up to 22% and 9% for spring cover and winter kill, respectively when predicting unobserved germplasm. Genome-wide-association-studies (GWAS) were utilized to detect genetic variants with marginal effects (environment-independent effect) and conditional effects (environment-dependent effects). Results showed the presence of large-effect genetic variants with marginal effects, in addition to few QTL whose effects were adaptive under specific environmental conditions while neutral or deleterious under different environmental conditions.ConclusionThis study demonstrates the usefulness and limitations of genomic prediction models for predicting GxE in highly diverse samples, and describes the extent of GxE interactions at the limit of species distribution for perennial ryegrass. Finally, our study points toward adaptive variation, which may enhance persistence of perennial ryegrass populations in Nordic and Baltic growing conditions.

Nitrate pollution in groundwater is a serious problem worldwide, as its concentration in many areas exceeds the WHO-defined drinking water standard (50 mg/L). Hydrogen-oxidizing bacteria (HOB) are a group of microorganisms capable of producing single-cell protein (SCP) using hydrogen and oxygen. Furthermore, HOB can utilize various nitrogen sources, including nitrate. This study developed a novel hybrid biological-inorganic (HBI) system that coupled a new submersible water electrolysis system driven by renewable electricity with HOB fermentation for in-situ nitrate recovery from polluted groundwater and simultaneously upcycling it together with CO2 into single-cell protein. The performance of the novel HBI system was first evaluated in terms of bacterial growth and nitrate removal efficiency. With 5 V voltage applied and the initial nitrate concentration of 100 mg/L, the nitrate removal efficiency of 85.52 % and raw of 47.71 % (with a broad amino acid spectrum) were obtained. Besides, the HBI system was affected by the applied voltages and initial nitrogen concentrations. The water electrolysis with 3 and 4 V cannot provide sufficient H2 for HOB and the removal of nitrate was 57.12 % and 59.22 % at 180 h, while it reached 65.14 % and 65.42 % at 5 and 6 V, respectively. The nitrate removal efficiency reached 58.40 % and 50.72 % within 180 h with 200 and 300 mg/L initial nitrate concentrations, respectively. Moreover, a larger anion exchange membrane area promoted nitrate removal. The monitored of the determination of different forms of nitrogen indicated that around 60 % of the recovered nitrate was assimilated into cells, and 40 % was bio-converted to N2. The results demonstrate a potentially sustainable method for remediating nitrate contaminant in groundwater, upcycling waste nitrogen, CO2 sequestration and valorization of renewable electricity into food or feed.

The central function of frustules—transparent glass shells surrounding the diatoms—is still enigmatic. This chapter summarizes some of the most common hypotheses related to frustule functionalities. They span a large variety of scientific domains, from protective functions and pore filtration to implications for photosynthesis via optical properties. We conclude that generalizations for the entire class can be hampered by the large biodiversity of diatoms; however, at the current state of this research, some general rules can be proposed: 1) Proposed functionalities related to the physicochemical material properties of silicon dioxide as the main chemical component of the frustules are more likely to affect all diatoms. 2) Some obvious frustule characteristics, such as those related to locomotion or excretion, bear secondary derived functionalities—these do not explain the existence of the frustule per se. Such traits are clearly restricted to particular taxonomic groups, such as motility via raphe slits in the evolutionary younger Bacillariophyceae. We discuss how the current approaches to investigating frustule functionality is limited by constraining experiments to only a few selected (model) species. A more systematic approach across the total biodiversity, guided by phylogeny and systematics and including the frustules of extinct species are required to better understand the role of the frustule, and its evolutionary origin.

Induced modification of plant gene expression is of both fundamental and applied importance. Cis-acting regulatory elements (CREs) are major determinants of the spatiotemporal strength of gene expression. Yet, there are few examples where induced genetic variation in predetermined CREs has been exploited to improve or investigate crop plants. The digital PCR based FIND-IT technology was applied to discover barley mutants with CRE variants in the promoter of the nutritional important barley grain phytase (PAPhy_a) gene. Mutants with higher or lower gene expression and ultimately higher or lower mature grain phytase activity (MGPA), respectively, were discovered. Field trials and inositol phosphate profiling during germination showed that PAPhy_a does not influence agronomic performance under the trial conditions but it does shorten the lag time of phosphate mobilization during germination. Higher endogenous MGPA is an improvement of grain quality for feed use as it improves the phosphate bioavailability for monogastric animals. Moreover, as the targeted CRE motifs of the PAPhy_a promoter are shared with a range of seed expressed genes like key cereal and legume storage genes, the current results demonstrates a concept for modulating individual gene expression levels of a range of seed genes.

Application of the mlo-based resistance in barley against powdery mildew attacks is a major success in crop breeding, since it confers durable disease resistance. Resistance caused by mutations in the Mlo gene seems to be ubiquitous across a range of species. This work addresses the introduction of mlo-based resistance into hexaploid wheat, which is complicated by the occurrence of three homoeologous genes: Mlo-A1, Mlo-B1 and Mlo-D1. EMS-generated mutant plants were screened for mutations in the three homoeologues. We selected and combined 6, 8, and 4 mutations, respectively, to obtain triple homozygous mlo mutant lines. Twenty-four mutant lines showed highly effective resistance towards attack by the powdery mildew pathogen under field conditions. All 18 mutations appeared to contribute to resistance; however, they had different effects on the occurrence of symptoms such as chlorotic and necrotic spots, which are pleiotropic to the mlo-based powdery mildew resistance. We conclude that to obtain highly effective powdery mildew resistance in wheat and to avoid detrimental pleiotropic effects, all three Mlo homoeologues should be mutated; however, at least one of the mutations should be of the weaker type in order to alleviate strong pleiotropic effects from the other mutations.

Plant membrane transporters controlling metabolite distribution contribute key agronomic traits1-6. To eliminate anti-nutritional factors in edible parts of crops, the mutation of importers can block the accumulation of these factors in sink tissues7. However, this often results in a substantially altered distribution pattern within the plant8-12, whereas engineering of exporters may prevent such changes in distribution. In brassicaceous oilseed crops, anti-nutritional glucosinolate defence compounds are translocated to the seeds. However, the molecular targets for export engineering of glucosinolates remain unclear. Here we identify and characterize members of the USUALLY MULTIPLE AMINO ACIDS MOVE IN AND OUT TRANSPORTER (UMAMIT) family-UMAMIT29, UMAMIT30 and UMAMIT31-in Arabidopsis thaliana as glucosinolate exporters with a uniport mechanism. Loss-of-function umamit29 umamit30 umamit31 triple mutants have a very low level of seed glucosinolates, demonstrating a key role for these transporters in translocating glucosinolates into seeds. We propose a model in which the UMAMIT uniporters facilitate glucosinolate efflux from biosynthetic cells along the electrochemical gradient into the apoplast, where the high-affinity H+-coupled glucosinolate importers GLUCOSINOLATE TRANSPORTERS(GTRs) load them into the phloem for translocation to the seeds. Our findings validate the theory that two differently energized transporter types are required for cellular nutrient homeostasis13. The UMAMIT exporters are new molecular targets to improve nutritional value of seeds of brassicaceous oilseed crops without altering the distribution of the defence compounds in the whole plant.

Abstract The sense of smell plays an essential role in the sensory evaluation of coffee. However, a precise sensory evaluation also requires good memory and the ability to stay focused and concentrated. This study aimed to investigate the effect of an online sensory and cognitive training program on the odor recognition of 36 coffee aromas. A total of 44 coffee professionals participated in a randomized crossover trial. It consisted of an online training program with different sensory and cognitive tasks over two periods of 6 weeks. The participants were divided into three study groups for data analysis purposes: a Control‐first group (n = 16), a matching Intervention‐first group (n = 16), and a second Intervention‐first‐residual group (n = 12) to check for repeatability of the test results. On average, the participants improved their odor recognition score by 15% after 6 weeks of training (p < .01) and maintained a high‐performance level after the control period. A positive correlation between completed training and improvement was observed (p < .001). The participants significantly improved their ability to detect the 36 Le Nez du Café aromas commonly used in the Specialty Coffee Association (SCA) and the Coffee Quality Institute (CQI) exam systems.Practical ApplicationsThe new online training program is a promising tool for improving the odor recognition of coffee professionals. The sensory training can easily be accomplished as it is executable off‐site, is self‐instructive, and does not require any supervision. A further generalization of this new odor‐training program for noncoffee professionals may potentially train people with prolonged loss in olfactory function, such as observed in coronavirus disease 2019 patients.

Perennial grain crops could make a valuable addition to sustainable agriculture, potentially even as an alternative to their annual counterparts. The ability of perennials to grow year after year significantly reduces the number of agricultural inputs required, in terms of both planting and weed control, while reduced tillage improves soil health and on-farm biodiversity. Presently, perennial grain crops are not grown at large scale, mainly due to their early stages of domestication and current low yields. Narrowing the yield gap between perennial and annual grain crops will depend on characterizing differences in their life cycles, resource allocation, and reproductive strategies and understanding the trade-offs between annualism, perennialism, and yield. The genetic and biochemical pathways controlling plant growth, physiology, and senescence should be analyzed in perennial crop plants. This information could then be used to facilitate tailored genetic improvement of selected perennial grain crops to improve agronomic traits and enhance yield, while maintaining the benefits associated with perennialism.