A metabolic flux efficiency model reveals mitochondrial triage: H2S reallocates carbon skeletons to match cysteine under cyanide stress in rice
Abstract
Hydrogen sulfide (H2S) achieves comparable growth recovery to cysteine (Cys) in rice under cyanide (CN-) stress, despite Cys being the direct substrate for CN- detoxification and driving a substantially higher assimilation rate via β-cyanoalanine synthase (β-CAS). This paradox implies a fundamental trade-off between immediate detoxification and long-term resilience. Here, we profiled tissue-resolved metabolomics of the TCA cycle intermediates oxaloacetate (OAA) and α-ketoglutarate (α-KG), and their cognate aspartate (Asp)- and glutamate (Glu)-family amino acids, the branches most intimately linked to CN- assimilation, together with transcriptional analysis of their biosynthetic genes. We then developed a Metabolic Flux Efficiency (MFE) model, a proof-of-concept framework that integrates these data to estimate relative flux efficiency within the TCA–amino acid (AA) cycle. H2S is proposed to execute a mitochondrial triage strategy, depleting root nitrogen reserves (Asn and Gln reduced by 92% and 67%) to liberate carbon skeletons, while boosting root α-KG (+93%) to sustain anaplerotic TCA cycle flux. The calibrated MFE model (Asp family: α = 0.39, β = 1.52; Glu family: α = 0.37, β = 1.64) suggests that metabolic conversion dominates over transcription in governing flux under CN- stress, and predicts that H2S redirects flow away from primary nitrogen assimilation (Glu→Gln) toward energy-generating cycles (Orn→Cit). This pattern is consistent with recovery being governed not by nitrogen abundance but by dynamic reallocation of carbon skeletons from storage to biosynthetic and anaplerotic routes. By redefining the mitochondrion as a metabolic regulatory hub that prioritizes reconstruction over mere survival, our work provides a quantitative framework for interpreting metabolic trade-offs and a conceptual basis for engineering stress-resilient crops.
Related
- The plant-beneficial fungus Gongronella butleri w5 reallocates plant-derived sucrose to enrich IAA-producing bacteria to promote plant root development in phosphorus-rich soil
- OPA1-dependent mitochondrial remodeling coordinates TCR signaling and metabolic adaptation during iNKT cell differentiation
- Mitochondrial transfer mediates metabolic communication between beta cells and islet macrophages
- Mitochondrial genetic effects mediate the response to stress through development, but not adult metabolic rate in Drosophila melanogaster
- Mitochondrial and metabolic plasticity distinguish stem cells from progenitors in the male germline
BibTeX
@article{kang2026metabolic,
title = {{A metabolic flux efficiency model reveals mitochondrial triage: H2S reallocates carbon skeletons to match cysteine under cyanide stress in rice}},
author = {Yi Kang and Cheng-Zhi Li and Xiao-Zhang Yu},
journal = {Frontiers in Plant Science},
year = {2026},
month = nov,
doi = {10.3389/fpls.2026.1904968},
url = {https://www.frontiersin.org/articles/10.3389/fpls.2026.1904968},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A metabolic flux efficiency model reveals mitochondrial triage: H2S reallocates carbon skeletons to match cysteine under cyanide stress in rice
AU - Yi Kang
AU - Cheng-Zhi Li
AU - Xiao-Zhang Yu
PY - 2026
DA - 2026/11/02
JO - Frontiers in Plant Science
DO - 10.3389/fpls.2026.1904968
UR - https://www.frontiersin.org/articles/10.3389/fpls.2026.1904968
AB - Hydrogen sulfide (H2S) achieves comparable growth recovery to cysteine (Cys) in rice under cyanide (CN-) stress, despite Cys being the direct substrate for CN- detoxification and driving a substantially higher assimilation rate via β-cyanoalanine synthase (β-CAS). This paradox implies a fundamental trade-off between immediate detoxification and long-term resilience. Here, we profiled tissue-resolved metabolomics of the TCA cycle intermediates oxaloacetate (OAA) and α-ketoglutarate (α-KG), and their cognate aspartate (Asp)- and glutamate (Glu)-family amino acids, the branches most intimately linked to CN- assimilation, together with transcriptional analysis of their biosynthetic genes. We then developed a Metabolic Flux Efficiency (MFE) model, a proof-of-concept framework that integrates these data to estimate relative flux efficiency within the TCA–amino acid (AA) cycle. H2S is proposed to execute a mitochondrial triage strategy, depleting root nitrogen reserves (Asn and Gln reduced by 92% and 67%) to liberate carbon skeletons, while boosting root α-KG (+93%) to sustain anaplerotic TCA cycle flux. The calibrated MFE model (Asp family: α = 0.39, β = 1.52; Glu family: α = 0.37, β = 1.64) suggests that metabolic conversion dominates over transcription in governing flux under CN- stress, and predicts that H2S redirects flow away from primary nitrogen assimilation (Glu→Gln) toward energy-generating cycles (Orn→Cit). This pattern is consistent with recovery being governed not by nitrogen abundance but by dynamic reallocation of carbon skeletons from storage to biosynthetic and anaplerotic routes. By redefining the mitochondrion as a metabolic regulatory hub that prioritizes reconstruction over mere survival, our work provides a quantitative framework for interpreting metabolic trade-offs and a conceptual basis for engineering stress-resilient crops.
SN - 1664-462X
ER -