Partial disruption of the Arabidopsis 2S seed storage proteins highlights the essential role of redox homeostasis in seed proteome plasticity and rebalancing

Arabidopsis seeds store most of their amino acids in the 12S and 2S seed storage proteins (SSPs). Elimination of the three most abundant 12S cruciferins (i.e., CRUA, CRUB, and CRUC) led to broad translational adjustments and redox homeostasis alteration. However, it remains unclear whether these responses are specific to major SSPs perturbation or represent core processes essential for proteome plasticity during seed filling, even if the perturbation is limited in scope. To address this question, we investigated the effects of disrupting the second most abundant SSPs, the 2S seed storage albumin (SESA) or napins. We performed physiological and proteomic analyses on a napin-RNAi mutant, which revealed that disruption of napins primarily affects oxidative homeostasis, with limited translational adjustment. These findings suggest that redox homeostasis is a fundamental response to proteomic perturbation during seed filling, whereas translational adjustments appear more contingent on the severity of disruption, particularly when large-scale compensatory protein response is required. Germination assays performed on cruciferin (cruabc) and napin (napin-RNAi) mutants highlighted the impact of redox homeostasis on seed germination. Notably, both mutants exhibited delayed germination, which was alleviated by supplementation with reactive oxygen species (ROS)-inducing agents. Importantly, analysis of the differentially expressed proteins that overlap between the two mutants identified a core set of proteins involved in proteome rebalancing. These shared targets represent promising candidates for future functional characterization and potential avenues for seed biofortification.