bims-plator 2026-04-05 papers

Issue of 2026–04–05
four papers selected by
Christian Meyer, INRAE

Plant Sci. 2026 Mar 31. pii: S0168-9452(26)00157-3. [Epub ahead of print] 113129

SnRK1 subcellular localization is linked to TOR signaling, chloroplast function, and salt stress tolerance in mature Arabidopsis leaves.

Lando Ana Paula, Maritano Paula Catalina, Barbieri Giuliano, Daloso Danilo, A Martínez-Noël Giselle, S Rodriguez Marianela.

Soil salinity can impair carbon fixation and ultimately decrease crop yield. To counteract this detrimental effect and maintain cellular homeostasis and productivity under stress, plants rely on metabolic and growth adaptations. Sucrose non-fermenting Related Kinase 1 (SnRK1) and Target of Rapamycin (TOR) kinases coordinate cellular metabolism and stress signaling. Despite substantial progress, major gaps persist regarding how SnRK1 subcellular localization affects TOR activity, chloroplast function, and overall metabolic balance under salinity in source leaves. We analyzed Arabidopsis mature leaves of plants expressing SnRK1α1 targeted to the nucleus (NLS-α1) or membrane/myristoylation (βMYR-α1) subjected to prolonged salinity (150mM NaCl, 14 days). Under control conditions, SnRK1 activity was low during the light period in wild-type (WT) leaves, however under salinity, both total and nuclear SnRK1 activity rose markedly at midday. Remarkably, the NLS-α1 plants exhibited increased tolerance, showing 10% less shoot biomass reduction than WT plants under salt stress. This may be related to the fact that mature leaves of NLS-α1 genotype showed intact chloroplast ultrastructure, higher photosynthetic performance, and elevated levels of threonine and stress-related metabolites under NaCl long-term exposure. Conversely, βMYR-α1 plants exhibited misregulated TOR activity, disrupted thylakoid structure with reduced photosynthetic efficiency and photodamage at PSII level, and the accumulation of photorespiratory intermediates. Overall, SnRK1 localization emerges as a spatial factor associated with organelle performance, metabolic reprogramming, and TOR signaling patterns during salt stress. Modulating SnRK1 intracellular distribution may, therefore, be a useful strategy for breeding or biotechnological approaches toward plant salinity tolerance.

Keywords: Arabidopsis; SnRK1 kinase; TOR kinase; chlorophyll fluorescence; chloroplast; metabolism; salt-stress; sugar signal

DOI: https://doi.org/10.1016/j.plantsci.2026.113129

New Phytol. 2026 Apr 02.

Multi-omics analysis of Raptor1A knockout reveals resistance to Tuta absoluta in tomato without growth penalties.

Limei Song, Ningning Zhang, Jiayue Tang, Yanling Zhang, Siyu Pei, Yinuo Ma, Hanxi Zhang, Shujie Dai, Jianghua Sun.

The Target of Rapamycin (TOR) signaling pathway plays a pivotal role in balancing plant growth and defense. However, the specific contribution of TOR complex components to insect resistance remains poorly understood. In this study, we identified and characterized SlRaptor1A, a scaffold protein of TOR complex 1 (TORC1), in tomato (Solanum lycopersicum), and revealed its function as a negative regulator of defense against the destructive pest Tuta absoluta. CRISPR-Cas9-mediated knockout of SlRaptor1A does not affect tomato growth and yield but confers enhanced resistance to T. absoluta. Integrated transcriptomic and metabolomic analyses showed that SlRaptor1A suppressed jasmonic acid (JA) and salicylic acid (SA) signaling pathways, reduced alkaloid accumulation, and downregulated phenylpropanoid biosynthesis during T. absoluta infestation. Slraptor1a mutants exhibited elevated levels of JA/SA and their derivatives, accompanied by upregulation of defense-related genes and accumulation of secondary metabolites potentially associated with insect resistance. Co-expression network analysis further confirmed the coordination of gene expression and metabolite production in response to infestation. These findings demonstrate that SlRaptor1A suppresses tomato defense through hormonal and metabolic regulation and provide a promising genetic target for breeding pest-resistant tomato cultivars without growth and yield penalties.

Keywords: Tuta absoluta; growth penalties; metabolomics; plant defense; regulatory‐associated protein TOR 1A; transcriptomics

DOI: https://doi.org/10.1111/nph.71123

Nat Commun. 2026 Mar 31. pii: 3116. [Epub ahead of print]17(1):

The ribosome-associated N-terminal acetyltransferase B coordinates global proteostasis and autophagy in plants by creating Ac/N-degrons.

Xiaodi Gong, Marlena Pożoga, Jean-Baptiste Boyer, Yuxing Xue, Thierry Meinnel, Tanja Bange, Carmela Giglione, Rüdiger Hell, Markus Wirtz.

The N-terminal acetyltransferase B (NatB) acetylates ~20% of the eukaryotic proteome. However, the role of NatB-mediated N-terminal acetylation (NTA) for the regulation of the proteome fate remains unclear in eukaryotes. In this study, we demonstrate that CRISPR-Cas9-mediated deletion of NatB activity in plants results in significantly lowered global protein turnover due to decreased ubiquitin-proteasome system (UPS) activity and protein translation. Quantitative proteomics uncovers that NatB substrates are significantly enriched in the fraction of stabilized proteins in natb mutants. We provide direct evidence that the absent NTA of KIN11, a subunit of the autophagy-controlling energy sensor SnRK1, protects it from UPS-mediated destruction. The resulting accumulation of KIN11 is responsible for the increased resistance of natb mutants to energy limitation induced by prolonged darkness. Our findings establish NatB as a central regulator of UPS-autophagy interplay and highlight its role in maintaining proteome stability and enabling dynamic stress responses in plants.

DOI: https://doi.org/10.1038/s41467-026-71208-2

Trends Biochem Sci. 2026 Mar 30. pii: S0968-0004(26)00037-X. [Epub ahead of print]

Molecular and structural mechanisms of nutrient sensing in the mTORC1 pathway.

Serim Yang, Tong Bian, Roberto Zoncu.

Primary nutrient sensors directly bind metabolites and undergo conformational changes that signal through core pathways to coordinate metabolic and cellular outcomes. Sensing of amino acids, lipids, sugars, and nucleotides is critical for the master growth regulatory Ser/Thr kinase, mechanistic target of rapamycin complex 1 (mTORC1), to promote growth and proliferation. Systematic proteomic and bioinformatic studies have accelerated the discovery of primary nutrient sensors upstream of mTORC1, whereas structural biology has shed light on how binding to their cognate metabolites triggers mTORC1-dependent signaling responses. This review focuses on recently reported amino acid and lipid sensors upstream of mTORC1 and highlights structural and functional features of these sensors that illuminate fundamental principles of nutrient detection and signal transduction.

Keywords: CASTOR1; LYCHOS; amino acid sensors; cholesterol sensors; metabolites; primary nutrient sensor

DOI: https://doi.org/10.1016/j.tibs.2026.02.009