Authors
Xumei Jia, Wenqing Liu, Shuo Xu, Weiyu Miao, Xulin Xian, Lanlan Hao, Zhongxing Zhang, Zhijun Zhang, Yanxiu Wang, Fengwang Ma, Chao Li
Published in
Plant, cell & environment. Aug 11, 2026. Epub Aug 11, 2026.
Abstract
Saline-alkali stress is a major abiotic factor that compromises plant growth, crop yield, and quality. Cytokinin plays an essential role in plant responses to saline-alkali stress; however, the underlying molecular mechanisms remain unclear in apple (Malus domestica). In this study, CYTOKININ OXIDASE/DEHYDROGENASE7 (MdCKX7) was identified as a positive regulator of saline-alkali tolerance in apple, encoding a functional CKX enzyme that mediates cytokinin degradation. Consistently, applying exogenous lovastatin, an inhibitor of cytokinin biosynthesis, alleviated the saline-alkali-sensitive phenotype in MdCKX7-silenced plants by promoting stomatal closure through cytokinin degradation. Molecular genetic assays revealed that apple transcription factor MdSPL1 is involved in the response to saline-alkali stress by directly activating the expression of MdCKX7. Overexpression of MdSPL1 enhanced saline-alkali tolerance by modulating photosynthetic efficiency and stomatal aperture, whereas its silencing resulted in increased sensitivity. Furthermore, overexpression of MdCKX7 in the MdSPL1-RNAi background rescued the saline-alkali-sensitive phenotype. Further analysis revealed that MdNF-YB4, a positive regulator of saline-alkali tolerance, interacts with MdSPL1 to facilitate its transcriptional activation of MdCKX7. Collectively, our study reveals the MdSPL1-MdNF-YB4-MdCKX7 regulatory module that orchestrates cytokinin-mediated saline-alkali tolerance in apple, providing valuable molecular tools for the breeding of saline-alkali-tolerance apple varieties.
PMID:
42578962
Bibliographic data and abstract were imported from PubMed on 11 Aug 2026.
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