The cytosolic glutamine synthetase GLN1;2 plays a role in the control of plant growth and ammonium homeostasis in Arabidopsis rosettes when nitrate supply is not limiting

Glutamine synthetase (EC 6.3.1.2) is a key enzyme of ammonium assimilation and recycling in plants where it catalyses the synthesis of glutamine from ammonium and glutamate. In Arabidopsis, five GLN1 genes encode GS1 isoforms. GLN1;2 is the most highly expressed in leaves and is over-expressed in roots by ammonium supply and in rosettes by ample nitrate supply compared with limiting nitrate supply. It is shown here that the GLN1;2 promoter is mainly active in the minor veins of leaves and flowers and, to a lower extent, in the parenchyma of mature leaves. Cytoimmunochemistry reveals that the GLN1;2 protein is present in the companion cells. The role of GLN1;2 was determined by examining the physiology of gln1;2 knockout mutants. Mutants displayed lower glutamine synthetase activity, higher ammonium concentration, and reduced rosette biomass compared with the wild type (WT) under ample nitrate supply only. No difference between mutant and WT can be detected under limiting nitrate conditions. Despite total amino acid concentration was increased in the old leaves of mutants at high nitrate, no significant difference in nitrogen remobilization can be detected using 15N tracing. Growing plants in vitro with ammonium or nitrate as the sole nitrogen source allowed us to confirm that GLN1;2 is induced by ammonium in roots and to observe that gln1;2 mutants displayed, under such conditions, longer root hair and smaller rosette phenotypes in ammonium. Altogether the results suggest that GLN1;2 is essential for nitrogen assimilation under ample nitrate supply and for ammonium detoxification

Acrylamide: new European risk management measures and prospects for reducing the acrylamide-forming potential of wheat

Acrylamide (C3H5NO) is a processing contaminant formed from free asparagine and reducing sugars during high-temperature cooking and processing. It is a Group 2A carcinogen, and the European Food Safety Authority (EFSA) Panel on Contaminants in the Food Chain (CONTAM Panel) has expressed concern for the potential tumor-inducing effects of dietary exposure. Potato, coffee, and cereal products are the major contributors to dietary acrylamide intake. The European Commission recently introduced strengthened risk management regulations for acrylamide in food, including compulsory mitigation measures and new benchmark levels. Measures adopted to reduce acrylamide formation in potato chips in Europe resulted in a 53% decrease from 2002 to 2011. However, since 2011 there has been a leveling off, suggesting that the easy gains have already been made. Acrylamide levels in chips are influenced by seasonal and geographical factors, making regulatory compliance more difficult. In cereals, acrylamide formation is determined by free asparagine concentration, and this differs substantially between varieties. We would support the inclusion of information on grain asparagine concentration in variety descriptions. However, crop management, including ensuring good disease control and sulfur sufficiency, is also important. A key enzyme in asparagine synthesis is asparagine synthetase. Wheat has four asparagine synthetase genes, TaASN1–4. Gene expression and biochemical data have identified TaASN2 as a prime target for genetic interventions to reduce wheat’s acrylamide-forming potential

Genetic parameters of drought tolerance for agromorphological traits in eggplant, wild relatives, and interspecific hybrids

[EN] Crop wild relatives (CWRs) have barely been used in eggplant (Solanum melongena) breeding. However, introgression breeding may help in coping with the challenges posed by climate change. During the rainy and dry seasons, we evaluated nine accessions of eggplant, nine accessions of seven related species (of which six are CWRs and one is a cultivated relative), and 12 interspecific hybrids. Drought tolerance scores, calculated as ratios of growing rates and ratios of mean values during the rainy and dry seasons, were obtained for vegetative growth and yield-related traits. Considering the vegetative growth and yield-related traits evaluated, the F-1 hybrid progenies of eggplant with S. insanum MEL1 x INS2 and MEL4 x INS3, S. anguivi MEL6 x ANG1, and S. dasyphyllum MEL6 x DAS1, plus the S. sysimbriifolium accession SIS1, displayed drought tolerance. Small to large gaps were observed between phenotypic and genotypic CVs of drought tolerance scores, reflecting variable influence of environmental factors on drought tolerance of the traits evaluated. In addition, the narrow-sense heritability was generally moderate, indicating that genes with dominance and/or epistasis effects may be involved in the expression of drought tolerance. High genotypic correlations for drought tolerance scores between pairs of traits such as branching index and leaf length, leaf petiole diameter and plant height, number of stamens per flower, and fruit pedicel length suggest that drought tolerance of these traits is controlled by genes that are in linkage disequilibrium and/or have pleiotropic effects. The results are relevant for the development of drought-tolerant cultivars of eggplant.Universitat Politecnica de Valencia, Grant/Award Number: PAID06-18; Ministerio de Ciencia e Innovacion, Grant/Award Number: RTI-2018-094592-B-I00; Generalitat Valenciana, Grant/Award Number: APOSTD/2018/014; Global Crop Diversity Trust, Grant/Award Number: GS20001 This work was undertaken as part of the initiative ¿Adapting Agriculture to Climate Change: Collecting, Protecting and Preparing Crop Wild Relatives,¿ which is supported by the Government of Norway. The project is managed by the Global Crop Diversity Trust with the Millennium Seed Bank of the Royal Botanic Gardens, Kew, and implemented in partnership with national and international gene banks and plant breeding institutes around the world. For further information, see the project website: http://www.cwrdiversity.org/. Funding was also received from Ministerio de Ciencia, Innovación y Universidades, Agencia Estatal de Investigación and Fondo Europeo de Desarrollo Regional (Grant RTI-2018-094592-B-I00 from MCIU/AEI/FEDER, UE) and from Vicerrectorado de Investigación, Innovación y Transferencia de la Universitat Politecnica de Valencia (Ayuda a Primeros Proyectos de Investigación; PAID-06-18), Mariola Plazas is grateful to Generalitat Valenciana and Fondo Social Europeo for a postdoctoral contract (APOSTD/2018/014).Kouassi, AB.; Kouassi, KBA.; Sylla, Z.; Plazas Ávila, MDLO.; Fonseka, RM.; Kouassi, A.; Fonseka, H.... (2021). Genetic parameters of drought tolerance for agromorphological traits in eggplant, wild relatives, and interspecific hybrids. Crop Science. 61(1):55-68. https://doi.org/10.1002/csc2.20250556861

Reducing the acrylamide-forming potential of crop plants

Acrylamide is a food processing contaminant formed from free asparagine and reducing sugars during high-temperature cooking and processing. It is a Group 2A carcinogen, and EFSA’s CONTAM Panel has expressed concern for the potential tumour-inducing effects of dietary exposure. Fried, baked, roasted and toasted potato, coffee and cereal products are the major contributors to dietary acrylamide intake. The European Commission has recently introduced strengthened risk management regulations for acrylamide in food, including compulsory mitigation measures and new Benchmark Levels. Steps taken by manufacturers to reduce acrylamide formation in potato chips in Europe resulted in a 53 % decrease from 2002 to 2011. However, since 2011 there has been a levelling off, suggesting that the easy gains have already been made and further large reductions are unlikely. The acrylamide-forming potential of potatoes is influenced by seasonal and geographical factors, making regulatory compliance for potato products more difficult. In cereals, acrylamide formation is determined by free asparagine concentration: this differs substantially between varieties but is also very responsive to environmental factors and crop management. Ensuring good disease control and sulfur sufficiency are particularly important. The relationship between precursor concentration and acrylamide formation is more complex in potato, with the concentration of reducing sugars the more important parameter in most datasets but free asparagine concentration contributing to the variance. Storage is a key issue for potatoes due to the phenomena of cold and senescent sweetening. Investigations into the genetic control of acrylamide formation in wheat have focussed on asparagine metabolism, in particular asparagine synthetase, while biotech potatoes with reduced expression of asparagine synthetase and vacuolar invertase are already on the market in the USA