Extracellular Glycolytic Activities in Root Endophytic Serendipitaceae and Their Regulation by Plant Sugars

Endophytic fungi that colonize the plant root live in an environment with relative high concentrations of different sugars. Analyses of genome sequences indicate that such endophytes can secrete carbohydrate-related enzymes to compete for these sugars with the surrounding plant cells. We hypothesized that typical plant sugars can be used as carbon source by root endophytes and that these sugars also serve as signals to induce the expression and secretion of glycolytic enzymes. The plant-growth-promoting endophytes Serendipita indica and Serendipita herbamans were selected to first determine which sugars promote their growth and biomass formation. Secondly, particular sugars were added to liquid cultures of the fungi to induce intracellular and extracellular enzymatic activities which were measured in mycelia and culture supernatants. The results showed that both fungi cannot feed on melibiose and lactose, but instead use glucose, fructose, sucrose, mannose, arabinose, galactose and xylose as carbohydrate sources. These sugars regulated the cytoplasmic activity of glycolytic enzymes and also their secretion. The levels of induction or repression depended on the type of sugars added to the cultures and differed between the two fungi. Since no conventional signal peptide could be detected in most of the genome sequences encoding the glycolytic enzymes, a non-conventional protein secretory pathway is assumed. The results of the study suggest that root endophytic fungi translocate glycolytic activities into the root, and this process is regulated by the availability of particular plant sugars.Peer Reviewe

EPPN2020/FLOWERINGUNDERSTRESS – sensor and deep physiological phenotyping of terminal drought and heat-effects on chickpea flowering, seed yield and quality

Chickpeas (Cicer arietinum L.) are included in the Zero Hunger program, are the world’s second most cultivated food legume, and have one of the best nutritional compositions among the grain legumes. Drought typically reduces grain yield, namely when occurring during pod set and seed filling, which is further reduced in combination with elevated temperatures. With this EPPN2020 project, we focused the phenotyping during the critical flowering and seed filling stages. Phenological responses to terminal drought and heat were evaluated by non-invasive thermo-, multireflectance- and multifluorescence imaging in the Phenolab at the University of Copenhagen (DK) to relate physiological responses at plant level with the activity signatures of key enzymes of carbohydrate and antioxidant metabolism and its final impact on seed yield and quality. Two chickpea genotypes with high production potential were evaluated: Elvar, adapted to dry conditions; Electra, selected due to large seed size. The impact of high temperature was combined with a 40% or 10% watering regime and compared with plants kept at 40% watering regime and ambient temperature. The sensor based phenotyping in the Phenolab was complemented with seed yield and quality analysis. Both seed weight and seed number were negatively affected by high temperatures irrespectively of the watering regime. Seeds from both genotypes obtained under high temperature conditions showed increased protein content and lower starch. Protein content was further affected by the watering regime. Alterations in protein-to-starch indicates modifications in sink-source relationships. The differential effects were mirrored in distinct sensor based and biochemical biosignatures. This study contributes to the mechanistic knowledge on how combined effects of severe terminal drought and high temperature modulate sink capacity and chickpea productivity (yield and quality) and identifies predictive biomarkers for the breeding.info:eu-repo/semantics/publishedVersio

Functional phenomics for improved climate resilience in Nordic agriculture

The five Nordic countries span the most northern region for field cultivation in the world. This presents challenges per se with short growing seasons, long days and a need for frost tolerance. Climate change has additionally increased risks for micro-droughts and water logging as well as pathogens and pests expanding northwards. Thus, Nordic agriculture demands crops that are adapted to the special Nordic growth conditions and future climate scenarios. A focus on crop varieties and traits important to Nordic agriculture, including the unique resource of nutritious wild crops, can meet these needs. In fact, with a future longer growing season due to climate change the region could contribute proportionally more to the global agricultural production. This also applies to other northern regions, including the Arctic. To address current growth conditions, mitigate impacts of climate change and meet market demands, the adaptive capacity of crops that both perform well in northern latitudes and are more climate resilient has to be increased, and better crop management systems be built. This requires functional phenomics approaches that integrate versatile high-throughput phenotyping, physiology and bioinformatics. This review stresses key target traits, the opportunities of latitudinal studies and infrastructure needs for phenotyping to support Nordic agriculture.Peer reviewe

Functional phenomics for improved climate resilience in Nordic agriculture

The five Nordic countries span the most northern region for field cultivation in the world. This presents challenges per se with short growing seasons, long days and a need for frost tolerance. Climate change has additionally increased risks for micro-droughts and water logging as well as pathogens and pests expanding northwards. Thus, Nordic agriculture demands crops that are adapted to the special Nordic growth conditions and future climate scenarios. A focus on crop varieties and traits important to Nordic agriculture, including the unique resource of nutritious wild crops, can meet these needs. In fact, with a future longer growing season due to climate change the region could contribute proportionally more to the global agricultural production. This also applies to other northern regions, including the Arctic. To address current growth conditions, mitigate impacts of climate change and meet market demands, the adaptive capacity of crops that both perform well in northern latitudes and are more climate resilient has to be increased, and better crop management systems be built. This requires functional phenomics approaches that integrate versatile high-throughput phenotyping, physiology and bioinformatics. This review stresses key target traits, the opportunities of latitudinal studies and infrastructure needs for phenotyping to support Nordic agriculture.Peer reviewe

Exogenous classic phytohormones have limited regulatory effects on fructan and primary carbohydrate metabolism in perennial ryegrass (<i>Lolium perenne</i> L.)

Fructans are polymers of fructose and one of the main constituents of water-soluble carbohydrates in forage grasses and cereal crops of temperate climates. Fructans are involved in cold and drought resistance, regrowth following defoliation and early spring growth, seed filling, have beneficial effects on human health and are used for industrial processes. Perennial ryegrass (Lolium perenne L.) serves as model species to study fructan metabolism. Fructan metabolism is under the control of both synthesis by fructosyltransferases (FTs) and breakdown through fructan exohydrolases (FEHs). The accumulation of fructans can be triggered by high sucrose levels and abiotic stress conditions such as drought and cold stress. However, detailed studies on the mechanisms involved in the regulation of fructan metabolism are scarce. Since different phytohormones, especially abscisic acid (ABA), are known to play an important role in abiotic stress responses, the possible short term regulation of the enzymes involved in fructan metabolism by the five classical phytohormones was investigated. Therefore, the activities of enzymes involved in fructan synthesis and breakdown, the expression levels for the corresponding genes and levels for water-soluble carbohydrates were determined following pulse treatments with ABA, auxin (AUX), ethylene (ET), gibberellic acid (GA), or kinetin (KIN). The most pronounced fast effects were a transient increase of I- I activities by AUX, KIN, ABA, and ET, while minor effects were evident for 1-FEH activity with an increased activity in response to KIN and a decrease by GA. Fructan and sucrose levels were not affected. This observed discrepancy demonstrates the importance of determining enzyme activities to obtain insight into the physiological traits and ultimately the plant phenotype. The comparative analyses of activities for seven key enzymes of primary carbohydrate metabolism revealed no co-regulation between enzymes of the fructan and sucrose pool

Review:New sensors and data-driven approaches—A path to next generation phenomics

At the 4th International Plant Phenotyping Symposium meeting of the International Plant Phenotyping Network (IPPN) in 2016 at CIMMYT in Mexico, a workshop was convened to consider ways forward with sensors for phenotyping. The increasing number of field applications provides new challenges and requires specialised solutions. There are many traits vital to plant growth and development that demand phenotyping approaches that are still at early stages of development or elude current capabilities. Further, there is growing interest in low-cost sensor solutions, and mobile platforms that can be transported to the experiments, rather than the experiment coming to the platform. Various types of sensors are required to address diverse needs with respect to targets, precision and ease of operation and readout. Converting data into knowledge, and ensuring that those data (and the appropriate metadata) are stored in such a way that they will be sensible and available to others now and for future analysis is also vital. Here we are proposing mechanisms for “next generation phenomics” based on our learning in the past decade, current practice and discussions at the IPPN Symposium, to encourage further thinking and collaboration by plant scientists, physicists and engineering experts

Extracellular invertase is involved in the regulation of clubroot disease in Arabidopsis thaliana

Clubroot disease of Brassicaceae is caused by an obligatebiotrophic protist,Plasmodiophora brassicae. During root galldevelopment, a strong sink for assimilates is developed. Amongother genes involved in sucrose and starch synthesis and degra-dation, the increased expression of invertases has been observedin a microarray experiment, and invertase and invertase inhibitorexpression was confirmed using promoter::GUS lines ofArabi-dopsis thaliana. A functional approach demonstrates that inver-tases are important for gall development. Different transgeniclines expressing an invertase inhibitor under the control of tworoot-specific promoters,Pyk10andCrypticT80, which results inthe reduction of invertase activity, showed clearly reduced clu-broot symptoms in root tissue with highest promoter expression,whereas hypocotyl galls developed normally. These resultspresent the first evidence that invertases are important factorsduring gall development, most probably in supplying sugars tothe pathogen. In addition, root-specific repression of invertaseactivity could be used as a tool to reduce clubroot symptoms

Flowering under stress: phenomics and proteomics approaches to chickpea grain yield and quality.

Chickpea (Cicer arietinum) is a major player in the FAO Zero Hunger program “toolkit”. It is the second most cultivated food legume, a source of sustainable protein (and other nutrients) and contributes to improved soil health and lower fertilization input. Grain yield, seed protein content and nutritional quality were found to be largely affected by Genotype x Environment. In the Mediterranean regions, higher frequency, intensity and duration of droughts, as well as hotter droughts are being registered, thus interfering with agroecosystems’ structure, composition, and functions. A controlled conditions assay (non-invasive phenotyping@PhenoLab) was undertaken in two genotypes from the Portuguese chickpea breeding program (Elvas, INIAV). Results revealed that high temperature (32º C during the reproductive phase) and water regime (40% vs 10% soil water content) play a significant role in chickpea development, seed production and composition, and protein content. As seed biochemical signatures allow to discriminate between genotypes, the power protein-based methodologies in genotype assessment are highlighted. Because some proteins can resist gastrointestinal digestion and influence human health, the processed seed proteome (i.e. following soaking, boiling and in-vitro digestion) in three consecutive years was further analysed in field-grown chickpeas (Elvas, INIAV). The seed proteome was found to be highly conserved, with minor changes being attributed to the seed development conditions. Furthermore, in vitro digestion efficiently removed many anti-nutritional proteins. Combined phenotyping and omic´s approaches contribute to the mechanistic knowledge of how severe terminal drought and high temperature modulate sink capacity and productivity (yield and quality). The integrated use of phenomics and omics methodologies has significant potential to increase our understanding of plant growth and development and, thus, an efficient, knowledge-based management of crops and resources.Work supported by EMPHASIS-GO (HORIZON-INFRA-2021-DEV-02 contract n. 101079772), by the European Plant Phenotyping Network 2020 (EXCELLENT SCIENCE - Research Infrastructures contract n. 731013) and by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P. namelly: UCIBIO – Research Unit on Applied Molecular Biosciences (FCT UIDP/04378/2020; FCT UIDB/04378/ 2020); 4HB - Associate Laboratory Institute for Health and Bioeconomy (FCT LA/P/0140/2020); LEAF – Linking Landscape, Environment, Agriculture and Food (FCT UID/AGR/04129/2020); PhD fellowship SFRH/BD/70345/2010.info:eu-repo/semantics/publishedVersio