MdMYB44‐like positively regulates salt and drought tolerance via the MdPYL8‐MdPP2CA module in apple

• Published in: The Plant journal : for cell and molecular biology 2024-04, Vol.118 (1), p.24-41
• Main Authors: Chen, Cui, Zhang, Zhen, Lei, Ying‐Ying, Chen, Wen‐Jun, Zhang, Zhi‐Hong, Li, Xiao‐Ming, Dai, Hong‐Yan
• Format: Article
• Language: English
• Subjects: Abscisic acid; Abscisic Acid - metabolism; apple; Apples; Arabidopsis; Arabidopsis - metabolism; Drought Resistance; drought tolerance; Droughts; Gene Expression Regulation, Plant; genetically modified organisms; Homeostasis; Malus - genetics; Malus - metabolism; MdMYB44‐like; MdPP2CA; MdPYL8; Modules; Molecular modelling; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified - metabolism; Protein phosphatase; Proteins; salt tolerance; Salts; Sodium Chloride - pharmacology; Stress, Physiological; transcription (genetics); transcription factors; water stress
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.16584

SUMMARY Abscisic acid (ABA) is involved in salt and drought stress responses, but the underlying molecular mechanism remains unclear. Here, we demonstrated that the overexpression of MdMYB44‐like, an R2R3‐MYB transcription factor, significantly increases the salt and drought tolerance of transgenic apples and Arabidopsis. MdMYB44‐like inhibits the transcription of MdPP2CA, which encodes a type 2C protein phosphatase that acts as a negative regulator in the ABA response, thereby enhancing ABA signaling‐mediated salt and drought tolerance. Furthermore, we found that MdMYB44‐like and MdPYL8, an ABA receptor, form a protein complex that further enhances the transcriptional inhibition of the MdPP2CA promoter by MdMYB44‐like. Significantly, we discovered that MdPP2CA can interfere with the physical association between MdMYB44‐like and MdPYL8 in the presence of ABA, partially blocking the inhibitory effect of the MdMYB44‐like–MdPYL8 complex on the MdPP2CA promoter. Thus, MdMYB44‐like, MdPYL8, and MdPP2CA form a regulatory loop that tightly modulates ABA signaling homeostasis under salt and drought stress. Our data reveal that MdMYB44‐like precisely modulates ABA‐mediated salt and drought tolerance in apples through the MdPYL8–MdPP2CA module. Significance Statement Under salt and drought stress, ABA promotes MdMYB44‐like gene expression, and MdPYL8 interacts with MdMYB44‐like to form a protein complex that further strengthens the transcriptional inhibition of MdMYB44‐like on the MdPP2CA promoter. Interestingly, MdPP2CA interferes with the interaction between MdMYB44‐like and MdPYL8 in the presence of ABA, thereby reducing the transcriptional inhibition of MdPP2CA by the MdMYB44‐like‐MdPYL8 complex and thus balancing ABA signaling in plants.