Carbohydrate and amino acid dynamics during grain growth in four temperate cereals under well-watered and water-limited regimes

Grain development in cereals depends on synthesis and remobilisation compounds such as water-soluble carbohydrates (WSCs), amino acids (AAs), minerals and environmental conditions during pre-and post-anthesis. This study analyses the impact of water stress on metabolite (WSCs, AAs and nitrogen) dynamics between the source (leaves and stems) and sink (grain) organs in triticale, bread wheat, durum wheat and barley. Plants were grown in glasshouse conditions under well-watered (WW) and water-limited (WL) regimes (from flag leaf fully expanded until maturity). The results showed that the stem WSC content and the apparent mobilisation of WSC to the grain were much higher in triticale and were associated with its larger grain size and grain number. In the four cereals, grain weight and the number of kernels per spike were positively associated with stem WSC mobilisation. After anthesis, the AA concentration in leaves was much lower than in the grain. In grain, the main AAs in terms of concentration were Asn, Pro and Gln in triticale, bread, and durum wheat, and Asn, Pro and Val in barley. The water-limited regime reduced grain weight per plant in the four cereal species, but it had no clear effects on WSC content and AAs in leaves and grain. In general, triticale was less affected by WL than the other cereals.The first author (A.M.M.-E.) was supported by FONDECYT Postdoc 3160687. The research was funded by the grants, FONDECYT N◦ 1150353 and 1180252

Elevated CO2has concurrent effects on leaf and grain metabolism but minimal effects on yield in wheat

While the general effect of CO2 enrichment on photosynthesis, stomatal conductance, N content, and yield has been documented, there is still some uncertainty as to whether there are interactive effects between CO2 enrichment and other factors, such as temperature, geographical location, water availability, and cultivar. In addition, the metabolic coordination between leaves and grains, which is crucial for crop responsiveness to elevated CO2, has never been examined closely. Here, we address these two aspects by multi-level analyses of data from several free-air CO2 enrichment experiments conducted in five different countries. There was little effect of elevated CO2 on yield (except in the USA), likely due to photosynthetic capacity acclimation, as reflected by protein profiles. In addition, there was a significant decrease in leaf amino acids (threonine) and macroelements (e.g. K) at elevated CO2, while other elements, such as Mg or S, increased. Despite the non-significant effect of CO2 enrichment on yield, grains appeared to be significantly depleted in N (as expected), but also in threonine, the S-containing amino acid methionine, and Mg. Overall, our results suggest a strong detrimental effect of CO2 enrichment on nutrient availability and remobilization from leaves to grains.This work was supported by the Department of Industry, Energy and Innovation of the Government of Navarre (PI040 TRIGOCLIM). The technical support given by Inés Urretavizcaya, Petra Högy, and Jürgen Franzaring in harvesting and sample management is acknowledged. JC was supported by an Australia Awards PhD Scholarship. GT was supported by a Connect Talent Award from the Region Pays de la Loire – Angers Loire Metropole (France). Research at the Australian Grains Free Air CO2 Enrichment (AGFACE) facility was jointly run by the University of Melbourne and Agriculture Victoria with funding from the Grains Research and Development Corporation (under contract no. DAV00137) and the Australian Commonwealth Department of Agriculture and Water Resources (under contract no. FtRG 1193982-41). CAAS-FACE was supported by the National Key Research and Development Project (under contracts 2016YFD0300401 and 2019YFA0607403). The FACE experiment in Italy was supported by the AGER project ‘Durum wheat adaptation to global change: effect of elevated CO2 on yield and quality traits’ and by the collaboration CREA-CNR. Finally, the authors also acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)

Elevated CO2 has concurrent effects on leaf and grain metabolism but minimal effects on yield in wheat

While the general effect of CO2 enrichment on photosynthesis, stomatal conductance, N content, and yield has been documented, there is still some uncertainty as to whether there are interactive effects between CO2 enrichment and other factors, such as temperature, geographical location, water availability, and cultivar. In addition, the metabolic coordination between leaves and grains, which is crucial for crop responsiveness to elevated CO2, has never been examined closely. Here, we address these two aspects by multi-level analyses of data from several free-air CO2 enrichment experiments conducted in five different countries. There was little effect of elevated CO2 on yield (except in the USA), likely due to photosynthetic capacity acclimation, as reflected by protein profiles. In addition, there was a significant decrease in leaf amino acids (threonine) and macroelements (e.g. K) at elevated CO2, while other elements, such as Mg or S, increased. Despite the non-significant effect of CO2 enrichment on yield, grains appeared to be significantly depleted in N (as expected), but also in threonine, the S-containing amino acid methionine, and Mg. Overall, our results suggest a strong detrimental effect of CO2 enrichment on nutrient availability and remobilization from leaves to grains.This work was supported by the Department of Industry, Energy and Innovation of the Government of Navarre (PI040 TRIGOCLIM). The technical support given by Inés Urretavizcaya, Petra Högy, and Jürgen Franzaring in harvesting and sample management is acknowledged. JC was supported by an Australia Awards PhD Scholarship. GT was supported by a Connect Talent Award from the Region Pays de la Loire – Angers Loire Metropole (France). Research at the Australian Grains Free Air CO2 Enrichment (AGFACE) facility was jointly run by the University of Melbourne and Agriculture Victoria with funding from the Grains Research and Development Corporation (under contract no. DAV00137) and the Australian Commonwealth Department of Agriculture and Water Resources (under contract no. FtRG 1193982-41). CAAS-FACE was supported by the National Key Research and Development Project (under contracts 2016YFD0300401 and 2019YFA0607403). The FACE experiment in Italy was supported by the AGER project ‘Durum wheat adaptation to global change: effect of elevated CO2 on yield and quality traits’ and by the collaboration CREA-CNR. Finally, the authors also acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI

[CO2] x drought interaction on protein remobilizing capacity of durum wheat plants during grain filling

Trabajo presentado en el Physiological traits that might be relevant for future cereal breeding, organizado por la Red de Fisiología del Rendimiento y Calidad para la Mejora de Cereales, celebrado en Lleida (España), el 16 de diciembre de 201

Durum Wheat Grain Yield and Quality under Low and High Nitrogen Conditions: Insights into Natural Variation in Low- and High-Yielding Genotypes

The availability and management of N are major determinants of crop productivity, but N excessive use has an associated agro-ecosystems environmental impact. The aim of this work was to investigate the influence of N fertilization on yield and grain quality of 6 durum wheat genotypes, selected from 20 genotypes as high- and low-yielding genotypes. Two N levels were applied from anthesis to maturity: high (½ Hoagland nutrient solution) and low (modified ½ Hoagland with one-third of N). Together with the agronomic characterization, grain quality analyses were assessed to characterize carbohydrates concentration, mineral composition, glutenin and gliadin concentrations, polyphenol profile, and anti-radical activity. Nitrogen supply improved wheat grain yield with no effect on thousand-grain weight. Grain soluble sugars and gluten fractions were increased, but starch concentration was reduced, under high N. Mineral composition and polyphenol concentrations were also improved by N application. High-yielding genotypes had higher grain carbohydrates concentrations, while higher concentrations in grain minerals, gluten fractions, and polyphenols were recorded in the low-yielding ones. Decreasing the amount of N to one-third ensured a better N use efficiency but reduced durum wheat agronomic and quality traits

Impact of N fertilization in agronomic and flour ntritional traits

Trabajo presentado en el I Simposio Español de Fisiología y Mejora de Cereales, celebrado en Zaragoza (España), los días 9 y 10 de abril de 2018The availability and management of N are major determinants of crop productivity and the associated environmental agro-ecosystems. Within this context, it is crucial to improve crop N use efficiency (NUE). The aim was to study the influence of N fertigation on yield and grain quality of durum wheat. In a first stage, 20 cultivars were watered with high N (HN, ½ Hoagland nutrient solution), whereas the other half was watered with low N (LN, modified ½ Hoagland with one-third of N). Based on yield and NUE data, six genotypes were selected for a secondary study in which deep flour nutritional traits were characterized. More specifically, together with the agronomic characterization, grain quality analyses were assessed to characterize mineral composition, carbohydrate concentration (soluble sugars and starch), glutenin and gliadin concentration, polyphenol quantitative profile, antioxidant activity, and dough viscosity profile. Obtained data showed that crop yield increased in HN whereas no differences were detected among genotypes. Mineral composition was not affected by N but was genotype-dependent. In fact, low yielding genotypes showed higher Ca, Cu, Fe, Mn and Zn concentrations. LN fertigation increased grain carbohydrate concentrations, showing genotypes with high yield the highest amounts. Furthermore, the increase of starch concentration under LN increased dough viscosity. Nitrogen supply improved grain quality through increases in gliadin and glutenin concentration, although without differences among genotypes. Contrary to this, under LN, the low yielding genotypes had the highest values. Flour total phenol concentration was significantly higher and bioaccessible phenols lower under HN. Low yielding genotypes had the highest values of total and bioaccessible phenols, and antiradical activity. Overall, our data show that decreasing the amount of N to one-third ensures durum wheat agronomic and quality traits, showing genotype 3 an efficient response to low N availability.Peer reviewe

Climate change, crop yields, and grain quality of c3 cereals: A meta‐analysis of [co2], temperature, and drought effects

Cereal yield and grain quality may be impaired by environmental factors associated with climate change. Major factors, including elevated CO2 concentration ([CO2]), elevated temperature, and drought stress, have been identified as affecting C3 crop production and quality. A me-ta‐analysis of existing literature was performed to study the impact of these three environmental factors on the yield and nutritional traits of C3 cereals. Elevated [CO2] stimulates grain production (through larger grain numbers) and starch accumulation but negatively affects nutritional traits such as protein and mineral content. In contrast to [CO2], increased temperature and drought cause significant grain yield loss, with stronger effects observed from the latter. Elevated temperature decreases grain yield by decreasing the thousand grain weight (TGW). Nutritional quality is also negatively influenced by the changing climate, which will impact human health. Similar to drought, heat stress decreases starch content but increases grain protein and mineral concentra-tions. Despite the positive effect of elevated [CO2], increases to grain yield seem to be counterbal-anced by heat and drought stress. Regarding grain nutritional value and within the three environmental factors, the increase in [CO2] is possibly the more detrimental to face because it will affect cereal quality independently of the region.This work was supported by European Interest Group (EIG) CONCERT-Japan (IRUEC), the Spanish Ministry of Science and Innovation (Spanish MINECO projects PCIN-2017-007 and PID2019-110445RB-I00). Sinda Ben Mariem had a PhD grant from the Navarra Governmen