Abstract
Inositol-requiring enzyme 1 (IRE1) is the most conserved transducer of the unfolded protein response that produces either adaptive or death signals depending on the amplitude and duration of its activation. Here, we report that SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 6 (SPL6)-deficient plants displayed hyperactivation of the endoplasmic reticulum (ER) stress sensor IRE1, leading to cell death in rice panicles, indicating that SPL6 is an essential survival factor for the suppression of persistent or intense ER stress conditions. Importantly, knockdown of the hyperactivated mRNA level of IRE1 rescues panicle apical abortion in the spl6-1 transgenic plants harbouring the IRE1-RNAi constructs, establishing the genetic linkage between the hyperactivation of IRE1 and cell death in spl6-1. Our findings reveal a novel cell survival machinery in which SPL6 represses the transcriptional activation of the ER stress sensor IRE1 in control of ER stress signalling outputs that hinge on a balance between adaptive and death signals for determining cell fates during ER stress.
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Acknowledgements
This study was supported by the Chinese Academy of Sciences (Strategic Priority Research Program XDPB0404), the Ministry of Science and Technology of China (National Key R&D Program of China, 2016YFD0100405), the National Natural Science Foundation of China (31770314 and 31570260) and the Chinese Academy of Sciences (XDA08010203). We thank the Rice T-DNA Insertion Sequence Database for providing the rice mutant lines; H.-T. Liu, X.-F. Yang and S.-Q. Zhao for suggestions and technical assistance; X.-Y. Gao, X.-S. Gao, J.-Q. Li and Z.-P. Zhang for assistance with electron microscopy and confocal microscopy.
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F.-Q.G. and Q.-L.W. supervised the project and designed the experiments. Q.-L.W., A.-Z.S., S.-T.C. and L.-S.C. performed the experiments. Q.-L.W., A.-Z.S. and S.-T.C. analysed the data and interpreted the results. F.-Q.G. and Q.-L.W. wrote the manuscript.
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Wang, QL., Sun, AZ., Chen, ST. et al. SPL6 represses signalling outputs of ER stress in control of panicle cell death in rice. Nature Plants 4, 280–288 (2018). https://doi.org/10.1038/s41477-018-0131-z
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DOI: https://doi.org/10.1038/s41477-018-0131-z
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