USDA Affiliation Dispute Triggers Expression of Concern Over Silicon-Cadmium Maize Study

A high-profile study suggesting that silicon can shield maize plants from toxic cadmium has been placed under an Editorial Expression of Concern by the journal Environmental Science and Pollution Research, after the United States Department of Agriculture revealed that one of the paper’s listed affiliations was inaccurate. The notice, published by the journal’s Editor-in-Chief and publisher, Springer Nature, does not retract the findings outright. Instead, it asks readers to treat the paper’s authorship and institutional attributions with caution, a middle step in the scholarly publishing system that flags potential problems while an investigation continues. The authors, notably, have agreed with the expression of concern, an unusual and notable concurrence that suggests the factual basis of the notice is not in dispute.

At the center of the matter is Tariq Shah, listed as the first author of the original paper, which appeared in the journal in November 2023 under the title describing how silicon inhibits cadmium uptake by regulating genes tied to the lignin biosynthetic pathway and plant hormone signal transduction in maize. In the published version of record, Shah’s affiliation was given as the Plant Science Research Unit of the Agricultural Research Service, part of the United States Department of Agriculture, in Raleigh, North Carolina. According to the expression of concern, the USDA has informed the journal that Shah was never affiliated with that research unit. That discrepancy, involving a claimed connection to a major American federal research agency, was serious enough for the journal to alert its readership formally.

Expressions of concern occupy a peculiar and often misunderstood niche in the architecture of research integrity. A full retraction signals that a paper’s findings or conduct are so compromised that the work should no longer be considered part of the reliable literature. A correction handles smaller errors, such as a misspelled name or a mislabeled figure. The expression of concern sits between these poles: it is issued when editors have substantial worries about a paper but cannot yet, or may never, reach a definitive judgment about whether the problems invalidate the science. In this case, the stated problem concerns institutional attribution rather than the experimental data themselves, which is why the journal chose the caution flag rather than immediate retraction.

The mechanics of how such a notice comes to be are worth understanding, because they reveal how the modern publishing ecosystem polices itself. Journals routinely verify author affiliations during or after peer review, and federal agencies such as the USDA occasionally audit publications that claim their units as institutional homes. When a discrepancy surfaces, the editor-in-chief consults with the publisher’s research integrity team, may contact the authors for explanation, and then decides on the appropriate notice. Here, the published statement indicates that the USDA itself communicated the inaccuracy to the journal, and that the authors concurred with the resulting notice. That agreement typically shortens what can otherwise be a months-long or years-long dispute, since contested expressions of concern often devolve into prolonged correspondence between editors, institutions, and author teams.

For readers and researchers who cite the work, the practical implications are significant. Citation databases such as Web of Science and Scopus link expressions of concern to the original record, and CrossMark, the version-of-record service operated by Crossref, now flags the article’s page with an update notice. Scientists who had relied on the paper’s conclusions about silicon-mediated cadmium tolerance in maize must now weigh the affiliation problem when deciding whether to cite the work, and many journals’ guidelines advise citing such papers with an explicit note about the concern. The journal’s own notice advises readers to interpret both the authorship and the institutional attribution with caution, language that stops short of questioning the data but clearly signals that the paper’s provenance cannot be taken at face value.

The underlying science, however, remains a topic of genuine importance, which is part of why the paper attracted attention in the first place. Cadmium is one of the most troublesome heavy-metal contaminants in agricultural soils worldwide. It enters croplands through industrial emissions, phosphate fertilizers, sewage sludge, and irrigation with contaminated water, and unlike many pollutants it is readily taken up by plant roots and translocated into shoots and grain. In humans, chronic dietary cadmium exposure damages the kidneys, weakens bones, and is classified as a carcinogen. Rice and maize, staple cereals feeding billions, are particularly efficient cadmium accumulators under certain soil conditions, making the search for practical mitigation strategies a global food-safety priority rather than an academic curiosity.

Silicon has emerged over the past two decades as one of the most promising tools in that search. Although silicon is not classified as an essential element for most plants, it is abundantly taken up by grasses, including maize, in the form of silicic acid from soil solution. Once inside the plant, silicon polymerizes into amorphous silica, depositing in root cell walls, endodermal tissues, and leaf surfaces. This deposition has well-documented physical effects: it thickens and toughens cell walls, which can act as a barrier that binds or blocks metal ions and reduces their apoplastic flow into the root stele. Silicon also modulates a suite of biochemical responses, including enhanced antioxidant enzyme activity, altered expression of metal transporter genes, and changes in the chemical speciation of cadmium within tissues, rendering the metal less biologically active.

The original paper’s title points to two molecular levers through which silicon was proposed to act. The first is lignin biosynthesis, the metabolic pathway that builds lignin, the phenolic polymer that gives vascular plants their structural rigidity and waterproofing. Lignification of root cell walls is known to influence metal uptake, because lignified barriers can immobilize cadmium in the outer root tissues and reduce its passage toward the xylem, the pipeline that carries water and dissolved minerals upward to the shoot. By upregulating genes encoding enzymes in the lignin pathway, silicon treatment could, in principle, reinforce this physical checkpoint. The second lever is plant hormone signal transduction, the network of perception and response cascades for regulators such as auxins, abscisic acid, jasmonates, and salicylic acid, which orchestrate stress responses. Hormone signaling intersects with metal stress at many points, controlling root architecture, stomatal behavior, and the transcriptional programs that activate detoxification machinery. A study connecting silicon, lignin genes, and hormone pathways in maize therefore addressed a coherent and mechanistically plausible hypothesis, one that fits within a broader and independently well-supported literature on silicon’s protective roles against abiotic and heavy-metal stress.

What happens next depends on the outcome of institutional and editorial processes that are not described in the notice. If further investigation were to uncover problems with the data or the experiments themselves, the expression of concern could be upgraded to a retraction. If the affiliation issue is resolved as an isolated administrative error, the journal could close the matter with the concern standing, or in some cases replace it with a correction of the author list. For now, the paper remains in the literature, stamped with a caution that the publishing system hopes readers will heed. The episode serves as a reminder that the credibility of a scientific paper rests not only on its data and methods but on the accuracy of its metadata, and that even a single misstated affiliation, when it involves a federal research agency, can ripple outward to touch how an entire body of work on cadmium-stressed maize is read, cited, and trusted.

Subject of Research: Editorial expression of concern regarding a study of silicon-mediated cadmium uptake inhibition in maize plants

Article Title: Editorial Expression of Concern: Silicon inhibits cadmium uptake by regulating the genes associated with the lignin biosynthetic pathway and plant hormone signal transduction in maize plants

Article References: Shah, T., Khan, Z., Khan, S. R., Imran, A., Asad, M., Ahmad, A., & Ahmad, P. (2026). Editorial Expression of Concern: Silicon inhibits cadmium uptake by regulating the genes associated with the lignin biosynthetic pathway and plant hormone signal transduction in maize plants. Environmental Science and Pollution Research, 33(27), 14041-14041. https://doi.org/10.1007/s11356-026-38189-7

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38189-7

Keywords: silicon, cadmium, maize, lignin biosynthesis, plant hormone signaling, heavy metal stress, editorial expression of concern, research integrity, USDA, affiliation misconduct, Environmental Science and Pollution Research, food safety