Rising Carbon Dioxide Reshapes Wheat Proteins, Threatening Bread Quality

Wheat feeds more people than almost any other crop on Earth, and the flour milled from its grains underpins a vast range of foods, from crusty loaves to pasta and pastries. Yet the very atmosphere that sustains the crop is changing in ways that alter what the grain is made of. A new field study led by the Leibniz Institute for Food Systems Biology at the Technical University of Munich shows that elevated carbon dioxide concentrations can significantly reshape the protein composition of wheat grains, with consequences that reach all the way from the bakery bench to questions of food tolerability in sensitive consumers.

The scale of the atmospheric shift is striking. Since 1980, the global carbon dioxide concentration has climbed from roughly 340 parts per million to about 425 parts per million in 2024, and depending on future socioeconomic pathways it could approach 600 parts per million by 2050. Wheat grown in the coming decades will therefore develop under air that is fundamentally different from the air in which nearly all modern cultivars were bred. Because the proteins stored in the grain determine both the technological performance of flour and the presence of molecules linked to wheat-related disorders, researchers have long wanted to know how this silent chemical transformation proceeds under realistic field conditions.

Such knowledge has been surprisingly scarce. Only a handful of field trials have examined how elevated carbon dioxide affects the full protein composition of wheat, largely because the experiments demand open-air facilities capable of enriching the atmosphere around growing crops while keeping every other variable intact. To close this gap, an interdisciplinary team from the Leibniz Institute, the Karlsruhe Institute of Technology, the Bavarian State Research Center for Agriculture, and the Forschungszentrum Jülich cultivated ten winter wheat cultivars under realistic growing and environmental conditions, exposing some plants to an elevated concentration of 546 parts per million while others grew under current ambient levels.

After harvest, the scientists analyzed the grain samples with a high-resolution mass spectrometric method they had developed themselves, allowing them to track individual protein families with unusual precision. Their attention centered on three groups with very different roles in the grain. Amylase/trypsin-inhibitors are the plant’s natural defense against herbivores but are also suspected of triggering allergies and contributing to non-celiac wheat sensitivity. Puroindolines largely determine kernel hardness and thereby shape the processing and baking properties of the flour. Gluten proteins, finally, are the backbone of breadmaking quality, yet they also contain specific amino acid sequences that digestive enzymes in the gastrointestinal tract cleave into celiac disease-active peptides, short chains of two to fifty amino acids that can provoke an immune response in genetically predisposed individuals.

The direction of the changes was consistent across the trial, but its magnitude was anything but uniform. Under elevated carbon dioxide, the content of amylase/trypsin-inhibitors generally increased, while the concentrations of puroindolines, gluten proteins, and certain celiac disease-active peptides derived from gluten during digestion decreased. How strongly each cultivar responded, however, depended largely on its genetic background. The reduced concentration of gluten proteins was associated with poorer baking quality, a finding that links the atmospheric environment directly to the loaf-forming potential of the flour.

The cultivar differences revealed by the full evaluation were among the most consequential results of the study. Nine of the ten cultivars lost grain protein under elevated carbon dioxide, with reductions ranging from 1.9 to 10.3 percent. The single exception was Hyvega, whose grain protein content actually rose by 2.7 percent under the same conditions. Across all parameters examined, Asory, Campesino, LG Initial, and Moschus reacted sensitively to the enriched atmosphere, whereas Apostel and KWS Emerick proved comparatively tolerant. These contrasts suggest that the breeding pool already contains genetic variation that could be harnessed to stabilize grain composition in a high-carbon-dioxide future.

For the researchers, the implications extend beyond baking performance. Katharina Scherf, who heads the Food Biopolymer Chemistry research group at the Leibniz Institute and is professor of Food Biopolymer Systems at the TUM School of Life Sciences, notes that the observed changes in amylase/trypsin-inhibitors and certain celiac disease-active peptides could be relevant in the long term for wheat-related diseases. She emphasizes, however, that further studies are needed to clarify the actual biological and immunological significance of these differences, a caution that reflects how complex the relationship between grain chemistry and human health remains. Celiac disease itself is a chronic disorder of the small intestine triggered mainly by gluten in genetically predisposed people, and it is still not fully understood which factors beyond genetic predisposition contribute to its development.

Sabrina Geisslitz, principal investigator and research associate in Scherf’s research group, underscores the practical message of the trial. The extent of the carbon-dioxide-induced changes depended largely on the specific wheat cultivar, she explains, and the results showed that the reduced gluten concentration went hand in hand with poorer baking quality. In other words, the same atmospheric shift that erodes the technological heart of the flour also modulates the protein fractions most often discussed in connection with wheat intolerability, making quality traits inseparable from the climate question.

The study, published in Food Chemistry under the title Elevated CO₂ induces cultivar-dependent changes in wheat proteins linked to wheat-related disorders and baking quality, arrives with a clear recommendation for plant breeding. As crops are adapted to climate change, the authors argue, selection should in the future focus not only on high yields but also on quality characteristics such as protein composition. The goal they identify is to breed wheat cultivars that maintain high baking quality even under rising carbon dioxide concentrations while containing as few potentially intolerable proteins as possible, a dual constraint that will test the creativity of cereal breeders worldwide.

The work was funded by the Federal Ministry of Agriculture, Food, and Regional Identity through the Federal Office for Agriculture and Food as part of the Innovation Promotion Program, project number 2818404B18, and co-funded by the European Union through the European Research Council project GLUTENOMICS. As the atmosphere continues its upward climb toward concentrations that no modern wheat has ever experienced in the field, the trial offers a rare empirical glimpse of what that future grain will look like, and a reminder that the quality of the world’s bread supply is now being written, molecule by molecule, in the air above the fields.

Subject of Research: Effects of elevated atmospheric carbon dioxide on the protein composition, baking quality, and wheat-related disease relevance of winter wheat cultivars

Article Title: Climate change affects the quality of one of the world’s most important staple foods

Article References: Climate change affects the quality of one of the world’s most important staple foods. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: climate change, carbon dioxide, wheat, protein composition, gluten, baking quality, celiac disease, amylase trypsin inhibitors, puroindolines, food chemistry, plant breeding, food security