bims-plator 2026-05-17 papers

Issue of 2026–05–17
four papers selected by
Christian Meyer, INRAE

J Eukaryot Microbiol. 2026 May-Jun;73(3):73(3): e70086

mTOR-Dependent Autophagy Is Conserved in the Ciliate Tetrahymena thermophila.

In Tetrahymena, autophagy appears to be involved in the integrity of the mitochondria which supply energy for active ciliary movement on the cell surface, the maintenance of various structures such as cilia, and cell shape changes associated with starvation. In this organism, which is evolutionarily distant from yeast and animal cells, the mechanisms controlling autophagy remain largely unknown. mTOR is a major regulatory factor that suppresses autophagy induction when cells are under nutrient-rich conditions. Previous studies suggest that T. thermophila contains two mTOR orthologs, but lacks the canonical TORC1 subunits, while retaining TORC2-associated components. To determine whether mTOR controls autophagy in T. thermophila, we examined Torin1, an ATP-competitive inhibitor that blocks mTOR kinase activity regardless of complex composition. It markedly triggered ATG8 puncta formation and mitochondrial degradation under nutrient-rich conditions. In contrast, rapamycin, a TORC1-specific inhibitor widely used to induce autophagy, did not affect cell growth or autophagy. These findings demonstrate that mTOR functions as a negative regulator of autophagy in T. thermophila, likely through a rapamycin-insensitive TORC2 or noncanonical complex. Our results highlight lineage-specific divergence in mTOR signaling architecture and expand our understanding of the diversity of autophagy regulation across eukaryotes.

Keywords: Tetrahymena ; Torin1; autophagy; mTOR

DOI: https://doi.org/10.1111/jeu.70086

J Integr Plant Biol. 2026 May 10.

The ZmRACK1-ZmCDPK7-ZmAPX1 module regulates plant antiviral immunity.

Yuyang Zhang, Niannian Li, Qiongqiong Wang, Yingchao Sun, Yajuan Shi, Lianwei Yu, Xiaoyu Han, Xiaoxi Feng, Zaifeng Fan, Linlin Chen, Honglian Li, Xue Yang, Hongxia Yuan, Yan Shi.

Calcium-dependent protein kinases (CDPKs) in plants play crucial roles in mediating responses to both biotic and abiotic stresses. However, the molecular mechanism through which CDPKs regulate antiviral immunity in plants remains largely elusive. In this study, we identified ZmCDPK7 as a key player in response to various stimuli. Lines overexpressing ZmCDPK7 exhibited enhanced resistance to maize chlorotic mottle virus (MCMV) infection, while ZmCDPK7 knock-out lines demonstrated increased sensitivity, indicating that ZmCDPK7 positively regulates maize immunity against MCMV. Furthermore, ZmCDPK7 interacts with ZmAPX1 and enhances its enzymatic activity by phosphorylating ZmAPX1 at Thr164, thereby reducing reactive oxygen species (ROS) production. The scaffold protein ZmRACK1 interacts with both ZmCDPK7 and ZmAPX1, facilitating the formation of a ternary complex that enhances ZmCDPK7-mediated ZmAPX1 enzymatic activity. Lines overexpressing ZmAPX1 also showed increased resistance to MCMV infection, while ZmAPX1 mutant lines (Zmapx1 MU1 and Zmapx1 MU2) exhibited increased sensitivity. Additionally, CRISPR/Cas9-mediated genome editing of ZmRACK1 in maize resulted in increased susceptibility to MCMV. To counteract plant defense, the MCMV protein P31 interacts with ZmCDPK7 and ZmRACK1, disrupting the interaction between ZmRACK1-ZmCDPK7 and ZmCDPK7-ZmAPX1, thereby blocking the ternary complex formation. Moreover, ZmCDPK7 is also implicated in defense against drought stress and corn stalk rot. Overall, our findings provide valuable insights into the molecular mechanisms by which the ZmRACK1-ZmCDPK7-ZmAPX1 module regulates plant immunity, identifying the potential new targets for the genetic control of maize viral diseases.

Keywords: calcium‐dependent protein kinase; maize; plant antiviral immunity

DOI: https://doi.org/10.1111/jipb.70285

Nat Chem Biol. 2026 May 14.

Genetically targeted mTORC1 inhibitor reveals transcriptional control by nuclear mTORC1.

Yanghao Zhong, Ayse Z Sahan, Zhengyao Shao, Qian-Yi Zhang, Xin Zhou, Jack G Haggett, Keiichi Koshizuka, Samuel A Myers, J Silvio Gutkind, Jin Zhang.

Mechanistic target of rapamycin complex 1 (mTORC1) is a nutrient sensor that integrates diverse inputs to regulate protein translation and cell growth. While mTORC1 is activated on the lysosome in the classical model, it has become increasingly clear that this multifaceted signaling complex is active at various subcellular locations, such as the nucleus. However, what specific functions mTORC1 serves at these locations and how its signaling is compartmentalized are unclear. To interrogate subcellular pools of mTORC1, we developed TerminaTOR, a genetically encodable inhibitor of mTORC1 that can be targeted to specific subcellular locations. When TerminaTOR is directed to the lysosome, it inhibits canonical lysosomal mTORC1 and induces autophagy. Furthermore, TerminaTOR targeted to the nucleus specifically inhibits nuclear mTORC1, uncovering noncanonical roles of nuclear mTORC1 in regulating the transcription of CCAAT motif-containing genes. Thus, mTORC1 exhibits functional spatial compartmentalization and TerminaTOR serves as a powerful tool for unraveling spatially regulated functions of mTORC1 across different scales.

DOI: https://doi.org/10.1038/s41589-026-02188-z

Plants (Basel). 2026 Apr 30. pii: 1369. [Epub ahead of print]15(9):

The RALF1-eIF4E1 Signaling Axis Mediates Root Hair Elongation, Flowering Time, and Stress Tolerance During Seed Germination and Early Root Growth in Arabidopsis thaliana.

Feirong Zeng, Pian Yang, Guixiang He, Aoxue Wang, Yan Gao, Jihong Zhang.

To investigate the coordinated role of RALF1 and eIF4E1 within the FER signaling module in regulating root hair elongation and stress responses in Arabidopsis thaliana, we constructed a ralf1/eif4e1 double mutant via conventional hybridization. Although the roles of the RALF1 and eIF4E1 genes are well known, the simultaneous absence of them remains poorly characterized. The double mutant exhibited significantly reduced root hair numbers and elongation and heightened sensitivity to ABA, Cd2+, and NaCl stress. The ralf1/eif4e1 double mutant exhibited delayed flowering time and higher numbers of rosette leaves. Fluorescence quantitative PCR analyses revealed that several key genes involved in regulating flowering such as FT, LFY and SOC reached maximum levels in wild-type plants. However, other genes that regulated floral meristem exhibited higher expression levels in the ralf1 mutant, followed by in wild-type plants. This work provides new insight into the RALF1-FERONIA-eIF4E1 module, demonstrating that it converges environmental cues to coordinately regulate root hair elongation, stress responses, and flowering time in Arabidopsis.

Keywords: Arabidopsis thaliana; RALF1; RALF1-FERONIA-eIF4E1 signaling; abiotic stress; eIF4E1; root hair

DOI: https://doi.org/10.3390/plants15091369