SC35-mediated bZIP49 splicing regulates K⁺ channel AKT1 for salt stress adaptation in poplar
Abstract Soil salinization threatens plant distribution, crop yields, and ecosystem stability. In response, plants activate potassium (K+) signaling to maintain Na⁺/K⁺ balance, though the mechanisms regulating K⁺ uptake under salt stress remain poorly understood. This study identified two splice var...
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| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-08-01
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| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-025-62448-9 |
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| Summary: | Abstract Soil salinization threatens plant distribution, crop yields, and ecosystem stability. In response, plants activate potassium (K+) signaling to maintain Na⁺/K⁺ balance, though the mechanisms regulating K⁺ uptake under salt stress remain poorly understood. This study identified two splice variants of the bZIP49 transcription factor in Populus tomentosa: unspliced “bZIP49L” and spliced “bZIP49S”. bZIP49S, the active form under salt stress, reduces salt tolerance when overexpressed, while bzip49cr knockout enhances it. The serine/arginine-rich splicing factor SC35 was identified as a regulator of bZIP49 mRNA splicing through a self-developed experimental method, and its overexpression enhances salt sensitivity. bZIP49S inhibits the K+ transporter AKT1 by binding its promoter, and AKT1 loss in bzip49cr mutant limits K+ influx and reduces salt tolerance. Under salt stress, the E2 ubiquitin-conjugating enzyme UBC32 promotes SC35 degradation via ubiquitination, lowering bZIP49S levels and alleviating the inhibition of AKT1. This facilitates K⁺ uptake, restores Na⁺/K⁺ balance, and improves salt tolerance. Our study highlights the critical role of bZIP49 splicing and the “UBC32-SC35-bZIP49-AKT1” module in modulating Na⁺/K⁺ balance under salt stress in poplar. |
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| ISSN: | 2041-1723 |