Triticum aestivum L. cv. Gazul is a spring wheat widely cultivated in Castilla y León (Spain). Potted plants were grown in a scenario emulating the climate change environmental conditions expected by the end of this century, i.e., with elevated CO₂ and high temperature under two water deficit regimes: long (LWD) and terminal (TWD). Changes in biomass and morphology, the content of proline (Pro), ascorbate (AsA) and glutathione (GSH), and enzymatic antioxidant activities were analyzed in flag leaves and ears. Additionally, leaf gas exchange was measured. LWD caused a decrease in biomass and AsA content but an increase in Pro content and catalase and GSH reductase activities in flag leaves, whereas TWD produced no significant changes. Photosynthesis was enhanced under both water deficit regimes. Increase in superoxide dismutase activity and Pro content was only observed in ears under TWD. The lack of a more acute effect of LWD and TWD on both organs was attributed to the ROS relieving effect of elevated CO₂. Gazul acted as a drought tolerant variety with anisohydric behavior. A multifactorial analysis showed better adaptation of ears to water deficit than flag leaves, underlining the importance of this finding for breeding programs to improve grain yield under future climate change.

A rapid and high throughput protocol to measure the catalase activity in vitro has been designed. Catalase is an enzyme with unusual kinetic properties because it does not follow the standard Michaelis–Menten model and is inactivated by H₂O₂. This makes the analysis of the two rate equations of the second-ordered reactions of the kinetic model rather complex. A two-degree polynomial fitting of the experimental data is proposed after transforming the exponential form of the integrated rate equation of the [H₂O₂] into a polynomial using the Taylor series. The fitting is validated by establishing an experimental linear relationship between the initial rate of the H₂O₂ decomposition and the protein concentration, regardless of the suicide inactivation that catalase might undergo beyond t > 0. In addition, experimental considerations are taken into account to avoid statistical bias in the analysis of the catalase activity. ANOVA analyses show that the proposed protocol can be utilized to measure the initial rate of the H₂O₂ decomposition by catalase in 32 samples in triplicates if kept below 8 mM min⁻¹ in the microplate wells. These kinetic and statistical analyses can pave the way for other antioxidant enzyme activity assays in microplate readers at small scale and low cost.

Nitrogen is the pivotal macronutrient for grain protein synthesis, which is important in human nutrition and the establishment of derived products. However, nitrogen metabolism in plants is likely to be susceptible to abiotic factors such as those derived from climate change: drought, elevated [CO2], and temperature. How the triple interaction of these factors will affect nitrogen metabolism and grain quality of cereals is unknown. This study aimed to determine the response of nitrogen metabolism in barley—one of the temperate cereals most tolerant to abiotic stresses—to the triple interaction during its whole life span. Our results pointed out a growth stage-dependent response on final nitrogen status. At the vegetative stage, the nitrogen assimilation capacity was boosted and matched with the biomass gain without altering the nitrogen status. However, at the anthesis and maturity stages, the nitrogen status of plants and grains was reduced. A non-overlapping effect of biomass dilution and lower mass flow is highlighted, while lower photorespiration activity cannot be completely ruled out. The elevated [CO2] is the main driver regulating nitrogen metabolism at the physiological level under future drought conditions, whereas elevated temperature hampers grain formation.

Predicted increases in the atmospheric CO₂ concentration and the earth’s mean surface temperature will be accompanied by a higher incidence of drought events. These environmental changes are likely to adversely affect crop productivity and quality, including wheat, an essential food in the human diet. We investigated the primary C-N metabolism response to drought stress at the whole-plant level and its dependence on plant development in bread wheat grown under combined elevated CO₂ and temperature. With this aim, the content of carbohydrates, nitrate, proteins and amino acids, together with the biomass were assessed in flag leaves and roots of wheat grown in controlled environment chambers at both ear emergence and anthesis stages. Multifactorial analysis revealed that the organ was the main factor explaining data variation. The physiological and biochemical traits in the flag leaves were more affected by drought than growth stage, leading to an accumulation of soluble carbohydrates, nitrate and amino acids. By contrast, roots were affected by the developmental stages but not by the treatment. The root content of fructose, glucose, starch and amino acids was higher at ear emergence than anthesis, whereas the accumulation of sucrose, fructans, proteins and nitrate increased at the latest growth stage. This study provides new insights into the reprograming of primary metabolism at whole plant level throughout the development in response to the future climate scenario, which could help to select traits ensuring sustainable food production systems that strengthen capacity for adaptation to climate change following the Sustainable Development Goals of 2030 Agenda.

Understanding the kinetic mechanism of enzyme inactivation by suicide substrate is of relevance for the optimal design of new drugs with pharmacological and therapeutic applications. Suicide substrate inactivation usually occurs via a two-step mechanism, although there are enzymes such as peroxidase and catalase in which the suicide inactivation by H₂O₂ happens in a single step. The approximate solution of the ordinary differential equation (ODE) system of the one step suicide substrate inactivation kinetics for a uni–uni reaction following the irreversible Michaelis–Menten model was previously analytically solved when accumulation of the substrate–enzyme complex was negligible, however not for more complex models, such as a ping-pong reaction, in which the enzyme is present in two active states during the catalytic turnover. To solve this issue, a theoretical approach was followed, in which the standard quasi-steady state and reactant stationary approximations were invoked. These approximations allowed for solving the ODE system of a ping-pong reaction with one substrate undergoing disproportionation when suicide inactivation was also present. Although the approximate analytical solutions were rather unwieldy, they were still valuable in qualitative analyses to explore the time course of the reaction products and identify the enzyme active state that irreversibly reacted with the suicide substrate during the reaction.