Under PEG-simulated water deficit, seeds receiving rutin germinated better than untreated controls. Rutin treatment was also associated with higher antioxidant enzyme activities and increased levels of osmotic-adjustment compounds. The researchers used correlation analysis, principal component analysis, grey relational analysis and an exploratory partial least squares structural equation model to characterize relationships among the physiological indicators.

The antioxidant-system and osmotic-adjustment scores were positively associated, with a path coefficient of 0.968. The partial path from the antioxidant system to oxidative-damage markers had a coefficient of −0.880, but its bootstrap interval included zero. Accordingly, the model did not establish a protective causal pathway linking the antioxidant system to reduced oxidative damage.

Candidate prioritization drew on 88 homology-mapped rutin-associated proteins and genes found to be differentially expressed under PEG-simulated water deficit. Their intersection produced seven candidates. An original protein–protein interaction analysis and a single-fit random forest analysis both prioritized FeRbohB, which the authors treated as exploratory computational evidence rather than independent biological validation.

FeRbohB was selected for further characterization because it was an RBOH-family candidate with direct relevance to reactive oxygen species biology. Quantitative real-time PCR in common buckwheat provided evidence concerning FeRbohB expression under the experimental treatments, while transient expression in Nicotiana benthamiana supplied phenotypic support in a heterologous system; neither experiment established that FeRbohB is necessary for the germination response observed in buckwheat. Structural and biophysical experiments provided further support for an interaction hypothesis.

Molecular docking generated a proposed configuration for rutin with FeRbohB, and a 100-nanosecond molecular dynamics trajectory explored the stability of that structural model. Microscale thermophoresis showed an apparent micromolar-affinity interaction between rutin and an engineered soluble construct, His-FeRbohBΔTM-mCherry, under the assay conditions. Because the construct was modified and lacked the native transmembrane region, the result cannot establish an interaction between rutin and native full-length FeRbohB in planta.

The study also does not demonstrate that FeRbohB regulates NADPH oxidase activity in common buckwheat. Taken together, the evidence supports FeRbohB as a candidate rutin-associated protein linked to reactive oxygen species homeostasis during PEG-simulated water deficit, but its precise role in germination and stress responses remains unresolved.

Subject of Research: FeRbohB and rutin-associated responses during PEG-simulated water deficit in common buckwheat germination

Article Title: Physiological and biophysical evidence associates FeRbohB with rutin-mediated responses to PEG-simulated water deficit during common buckwheat germination

Article References: Zhao, M., Ma, L., Zhou, C., Guo, Z., Zhou, M., Wang, Z., Yang, J., Shi, B., & Ruan, J. (2026). Physiological and biophysical evidence associates FeRbohB with rutin-mediated responses to PEG-simulated water deficit during common buckwheat germination. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10079-7

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10079-7

Keywords: common buckwheat, rutin, FeRbohB, seed germination, water deficit, reactive oxygen species, antioxidant enzymes, molecular docking, molecular dynamics, microscale thermophoresis, Physiological, biophysical