The FaAP2-11 Transcription Factor Putatively Regulates Cell Wall Remodeling and Stress-Acclimation Responses Under Drought and Salinity Stress

Abstract

APETALA2/ethylene-responsive factor (AP2/ERF) transcription factors are key regula-tors of plant responses to abiotic stress, integrating environmental and hormonal signals into coordinated transcriptional programs. RNA-seq analysis of strawberry (Fragaria × ananassa) leaves and roots subjected to drought and salinity identified 58 differentially expressed FaAP2/ERF genes. Promoter analysis revealed cis-regulatory elements associated with abscisic acid, jasmonate, ethylene, salicylic acid, and drought-responsive signaling. Among these genes, FaAP2-11 was selected for functional characterization because of its strong response to both stresses. Expression profiling revealed preferential transcript accumulation in immature achenes and sepals, while FaAP2-11 expression was induced by oxidative and nitrosative signals and stress-related phytohormones. Heterologous overexpression of FaAP2-11 in Nicotiana benthamiana enhanced photosynthetic performance and intrinsic water-use efficiency under osmotic and salinity stress. Transcriptomic analysis revealed extensive reprogramming affecting hormone signaling, cell wall remodeling, primary metabolism, and redox-related processes. This response was characterized by repression of genes involved in cell wall modification and cuticular wax biosynthesis, together with selective upregulation of lignification-associated genes. Collectively, these findings suggest that FaAP2-11 contributes to coordinating transcriptional and physiological responses associated with abiotic-stress acclimation and supports its potential as a candidate gene for improving drought and salinity resilience in strawberry.