Salt stress affects over 6% of global land area, leading to severe consequences for agricultural productivity. Apple trees, widely cultivated for their ecological adaptability and high nutritional value, are not immune to these challenges. The mechanism by which apples respond to salt stress is complex, involving both hormonal and genetic regulation. Jasmonic acid (JA), a plant hormone, has been shown to enhance salt tolerance, but its molecular underpinnings, particularly through WRKY transcription factors like MdWRKY9, were previously unclear. Given the increasing need for salt-tolerant crops, understanding these molecular mechanisms is crucial. Based on these challenges, in-depth research is needed to explore how MdWRKY9 interacts with other signaling pathways to mediate salt tolerance in apples.
In a new study published (DOI: 10.1093/hr/uhaf068) in Horticulture Research, researchers from Shandong Agricultural University have identified MdWRKY9, a transcription factor in apple, as a key player in salt stress tolerance. The study, published on March 4, 2025, reveals how MdWRKY9 interacts with the jasmonic acid (JA) signaling pathway to promote salt tolerance in apple trees by regulating genes involved in ion transport.
The researchers found that under salt stress, MdWRKY9 expression in apple roots significantly increased. Transgenic apples with overexpressed MdWRKY9 exhibited enhanced salt tolerance, displaying improved growth even under high salt concentrations. Notably, the study highlighted the role of MdWRKY9 in regulating MdNHX1 and MdSOS2, two genes crucial for maintaining ionic balance under salt stress. MdWRKY9 directly binds to the promoters of these genes, boosting their expression. Furthermore, the interaction between MdWRKY9 and JAZ proteins, repressors in the JA signaling pathway, was shown to be modulated by JA signaling, which triggers the degradation of JAZ proteins, releasing MdWRKY9 to activate downstream gene expression. This dynamic process is essential for maintaining cellular ion homeostasis during salt stress.
"Understanding how transcription factors like MdWRKY9 regulate salt tolerance at the molecular level opens new possibilities for improving crop resilience to environmental stresses," said Dr. Xuesen Chen, one of the lead researchers at Shandong Agricultural University. "Our findings underscore the importance of JA-mediated pathways in enhancing salt stress resistance, offering new strategies for developing salt-tolerant apple varieties."
The findings of this study could have significant implications for agricultural practices, particularly in regions affected by soil salinization. By harnessing the power of MdWRKY9, researchers and agronomists can develop genetically modified apple varieties with enhanced salt tolerance, potentially increasing apple yields in saline-prone areas. Additionally, this research could inform similar strategies for improving salt tolerance in other crops, contributing to global food security.
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References
DOI
10.1093/hr/uhaf068
Original Source URL
https://doi.org/10.1093/hr/uhaf068
Funding information
This work was supported by the Key Research and development Programs of Shandong Provence (2023CXPT013, 2022CXPT021), the National Key R&D Program of China (No.2023YFD1200100), and the Youth Innovation Team Program of Shandong Province (2022KJ236).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.