Browsing by Person "Tester, Mark"

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Characterization of epidermal bladder cells in Chenopodium quinoa
(2021) Otterbach, Sophie L.; Khoury, Holly; Rupasinghe, Thusitha; Mendis, Himasha; Kwan, Kim H.; Lui, Veronica; Natera, Siria H. A.; Klaiber, Iris; Allen, Nathaniel M.; Jarvis, David E.; Tester, Mark; Roessner, Ute; Schmöckel, Sandra M.
Chenopodium quinoa (quinoa) is considered a superfood with its favourable nutrient composition and being gluten free. Quinoa has high tolerance to abiotic stresses, such as salinity, water deficit (drought) and cold. The tolerance mechanisms are yet to be elucidated. Quinoa has epidermal bladder cells (EBCs) that densely cover the shoot surface, particularly the younger parts of the plant. Here, we report on the EBC's primary and secondary metabolomes, as well as the lipidome in control conditions and in response to abiotic stresses. EBCs were isolated from plants after cold, heat, high‐light, water deficit and salt treatments. We used untargeted gas chromatography–mass spectrometry (GC–MS) to analyse metabolites and untargeted and targeted liquid chromatography‐MS (LC–MS) for lipids and secondary metabolite analyses. We identified 64 primary metabolites, including sugars, organic acids and amino acids, 19 secondary metabolites, including phenolic compounds, betanin and saponins and 240 lipids categorized in five groups including glycerolipids and phospholipids. We found only few changes in the metabolic composition of EBCs in response to abiotic stresses; these were metabolites related with heat, cold and high‐light treatments but not salt stress. Na+ concentrations were low in EBCs with all treatments and approximately two orders of magnitude lower than K+ concentrations.
A comprehensive characterization of agronomic and end-use quality phenotypes across a quinoa world core collection
(2023) Craine, Evan B.; Davies, Alathea; Packer, Daniel; Miller, Nathan D.; Schmöckel, Sandra M.; Spalding, Edgar P.; Tester, Mark; Murphy, Kevin M.
Quinoa (Chenopodium quinoa Willd.), a pseudocereal with high protein quality originating from the Andean region of South America, has broad genetic variation and adaptability to diverse agroecological conditions, contributing to the potential to serve as a global keystone protein crop in a changing climate. However, the germplasm resources currently available to facilitate quinoa expansion worldwide are restricted to a small portion of quinoa’s total genetic diversity, in part because of day-length sensitivity and issues related to seed sovereignty. This study aimed to characterize phenotypic relationships and variation within a quinoa world core collection. The 360 accessions were planted in a randomized complete block design with four replicates in each of two greenhouses in Pullman, WA during the summer of 2018. Phenological stages, plant height, and inflorescence characteristics were recorded. Seed yield, composition, thousand seed weight, nutritional composition, shape, size, and color were measured using a high-throughput phenotyping pipeline. Considerable variation existed among the germplasm. Crude protein content ranged from 11.24% to 17.81% (fixed at 14% moisture). We found that protein content was negatively correlated with yield and positively correlated with total amino acid content and days to harvest. Mean essential amino acids values met adult daily requirements but not leucine and lysine infant requirements. Yield was positively correlated with thousand seed weight and seed area, and negatively correlated with ash content and days to harvest. The accessions clustered into four groups, with one-group representing useful accessions for long-day breeding programs. The results of this study establish a practical resource for plant breeders to leverage as they strategically develop germplasm in support of the global expansion of quinoa.
NAC transcription factors ATAF1 and ANAC055 affect the heat stress response in Arabidopsis
(2022) Alshareef, Nouf Owdah; Otterbach, Sophie L.; Allu, Annapurna Devi; Woo, Yong H.; de Werk, Tobias; Kamranfar, Iman; Mueller-Roeber, Bernd; Tester, Mark; Balazadeh, Salma; Schmöckel, Sandra M.; Alshareef, Nouf Owdah; Division of Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia; Otterbach, Sophie L.; Department Physiology of Yield Stability, Institute of Crop Science, University of Hohenheim, Stuttgart, Germany; Allu, Annapurna Devi; Department of Biology, Indian Institute of Science Education and Research (IISER), Tirupati, India; Woo, Yong H.; Division of Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia; de Werk, Tobias; Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany; Kamranfar, Iman; Institute of Biochemistry and Biology, University of Potsdam, Potsdam‐Golm, Germany; Mueller-Roeber, Bernd; Center of Plant Systems Biology and Biotechnology (CPSBB), Plovdiv, Bulgaria; Tester, Mark; Division of Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia; Balazadeh, Salma; Institute of Biology, Leiden University, Leiden, The Netherlands; Schmöckel, Sandra M.; Department Physiology of Yield Stability, Institute of Crop Science, University of Hohenheim, Stuttgart, Germany
Pre-exposing (priming) plants to mild, non-lethal elevated temperature improves their tolerance to a later higher-temperature stress (triggering stimulus), which is of great ecological importance. ‘Thermomemory’ is maintaining this tolerance for an extended period of time. NAM/ATAF1/2/CUC2 (NAC) proteins are plant-specific transcription factors (TFs) that modulate responses to abiotic stresses, including heat stress (HS). Here, we investigated the potential role of NACs for thermomemory. We determined the expression of 104 Arabidopsis NAC genes after priming and triggering heat stimuli, and found ATAF1 expression is strongly induced right after priming and declines below control levels thereafter during thermorecovery. Knockout mutants of ATAF1 show better thermomemory than wild type, revealing a negative regulatory role. Differential expression analyses of RNA-seq data from ATAF1 overexpressor, ataf1 mutant and wild-type plants after heat priming revealed five genes that might be priming-associated direct targets of ATAF1: AT2G31260 (ATG9), AT2G41640 (GT61), AT3G44990 (XTH31), AT4G27720 and AT3G23540. Based on co-expression analyses applied to the aforementioned RNA-seq profiles, we identified ANAC055 to be transcriptionally co-regulated with ATAF1. Like ataf1, anac055 mutants show improved thermomemory, revealing a potential co-control of both NAC TFs over thermomemory. Our data reveals a core importance of two NAC transcription factors, ATAF1 and ANAC055, for thermomemory.