Biology subjects

Rodriguez-Celma, J.

Publications and source records attributed to Rodriguez-Celma, J..

4 recordsLinked to original sources

bioRxiv2026

Redox-active di-O-methylated coumarins exudation contributes to genotype-dependent iron deficiency tolerance in soybean

Iron (Fe) deficiency is a widespread disorder limiting global soybean (Glycine max (L.) Merr.) production. Although root exudation is a key adaptive mechanism for Fe scarcity in species like Arabidopsis, a detailed chemical characterization of soybean exudates is lacking. Here, we examined the accumulation and secretion of phenolic compounds in soybean roots and their correlation with intraspecific tolerance to Fe-deficiency chlorosis. Seven soybean genotypes with contrasting tolerance, derived from U.S. breeding programs, were analyzed. Root exudates from Fe-deficient soybean plants solubilized ferric oxide. We identified and quantified 28 coumarin-type phenolics, with catechol methylsideretin as the predominant component. Although the qualitative coumarin profile was consistent across all genotypes, Fe-efficient lines secreted these compounds at higher levels or earlier during Fe deficiency than Fe-inefficient lines. The efficient genotype A7 showed coordinated upregulation of coumarin biosynthesis and secretion, whereas this response was weaker in the Fe-inefficient genotype IsoClark. Catechol methylsideretin concentrations strongly correlated with the ability of root exudates to mobilize Fe from ferric oxide. The conserved phenolic profile, together with divergence from those reported in non-legume species, suggests lineage-specific adaptations and ecological roles beyond Fe mobilization. These results highlight genotype-dependent exudation as a determinant of soybean Fe-deficiency tolerance, with implications for breeding. HIGHLIGHTIron deficiency induces soybean root exudates containing predominantly catechol methylsideretin which mobilize iron; genotypes differing in Fe efficiency show conserved qualitative but contrasting quantitative coumarin profiles.

plant biology↗

bioRxiv2024

Iron and redox sensing in plants: properties of the hemerythrin-like domains of Arabidopsis BRUTUS and BRUTUS-LIKE2 proteins

Iron uptake in plants is negatively regulated by highly conserved hemerythrin (Hr) E3 ubiquitin ligases exemplified by Arabidopsis thaliana BRUTUS (BTS). Physiological studies suggest these are the elusive plant iron sensors, but biochemical evidence is lacking. Here we demonstrate that the N-terminal domains of BTS and BTS-LIKE2 (BTSL2) respectively bind three and two diiron centres within three closely packed Hr-like subdomains. The centres can be reversibly oxidized by O2 and H2O2, resulting in a di-Fe3+ form that is non-labile. In the reduced state, a proportion of the iron becomes labile, based on accessibility to Fe2+ chelators and reconstitution experiments, consistent with dynamic iron binding. Impaired iron binding and altered redox properties in the BTS dgl variant correlate with diminished capacity to suppress the downstream signalling cascade. These data provide the biochemical foundation for a mechanistic model of how BTS/Ls function as iron sensors that are unique to the plant kingdom.

biochemistry↗

bioRxiv2022

The BRUTUS-LIKE E3 ligases BTSL1 and BTSL2 fine-tune transcriptional responses to balance Fe and Zn homeostasis

The mineral micronutrients zinc (Zn) and iron (Fe) are essential for plant growth and human nutrition, but interactions between the homeostatic networks of these two elements are not fully understood. Here we show that loss-of-function of BTSL1 and BTSL2, which encode partially redundant E3 ubiquitin ligases that negatively regulate Fe uptake, confers tolerance to Zn excess in Arabidopsis thaliana. Double btsl1 btsl2 mutant seedlings grown on high Zn medium accumulated similar amounts of Zn in roots and shoots as the wild type, but suppressed the accumulation of excess Fe in roots. RNA-seq analysis showed that roots of mutant seedlings had relatively higher expression of genes involved in Fe uptake (IRT1, FRO2, NAS) and in Zn storage (MTP3, ZIF1). Surprisingly, mutant shoots did not show the transcriptional Fe-deficiency response which is normally induced by Zn excess. Split-root experiments suggested that within roots the BTSL proteins act locally and downstream of systemic Fe deficiency signals. Together, our data show that constitutive low-level induction of the Fe-deficiency response protects btsl1 btsl2 mutants from Zn toxicity. We propose that BTSL protein function is disadvantageous in situations of external Zn and Fe imbalances, and formulate a general model for Zn-Fe interactions in plants. HighlightMutation of two E3 ligases that suppress iron uptake in roots also confers tolerance to zinc toxicity, identifying a regulatory point of interaction between iron and zinc homeostasis.

plant biology↗

bioRxiv2017

BRUTUS-LIKE proteins moderate the transcriptional response to iron deficiency in roots

Iron is an essential micronutrient but in excess is toxic inside cells. Under iron deficiency, the expression of iron uptake genes is increased, but it is not known how the transcriptional response is controlled to avoid uptake of too much iron. The hemerythrin E3 ligases BRUTUS (BTS) and BTS-LIKE (BTSL) have previously been identified as negative regulators of the iron deficiency response. Our phylogenetic analysis indicated that BTSL proteins are present in dicotyledonous plants only and form a separate clade from BTS homologs. BTSL1 and BTSL2 in Arabidopsis thaliana are in a network with nearly all iron uptake genes, whereas BTS is in a shoot-specific network. BTSL1 and BTSL2 are expressed predominantly in the root epidermis and cortex, separate from BTS in the root stele, shoot and embryos. Mutant analysis identified BTSL2 as the dominant paralog of the otherwise redundant BTSL genes. The btsl double mutant had increased protein levels of FIT, the FER-like Iron deficiency-induced Transcription factor, and failed to switch off the transcriptional response upon iron resupply, leading to dramatic iron accumulation in roots and shoots. Protein interaction between the C-terminus of BTSL proteins and FIT indicate that FIT is a direct target for degradation. Taken together, our studies show that BTSL1 and BTSL2 control iron uptake in the epidermis and cortex, upstream of BTS in the vasculature and leaves.

plant biology↗