Heat and drought stresses are among the most critical abiotic factors threatening floricultural crop production under accelerating climate change. Unlike food crops, where survival and yield are the primary concerns, the commercial value of ornamental plants is largely determined by aesthetic traits such as flower color, shape, fragrance, and vase life, which are highly sensitive to environmental stresses. This review provides an overview of the molecular mechanisms underlying heat and drought stress responses in plants, with particular emphasis on recent findings in major floricultural crops including chrysanthemum, rose, lily, and petunia, which were selected as representative species based on their commercial importance and the availability of recent molecular studies. Heat stress is primarily sensed through membrane fluidity changes, protein unfolding, and reactive oxygen species accumulation, triggering the heat shock transcription factor (HSF)-heat shock protein (HSP) signaling cascade. Drought stress is mediated principally through abscisic acid accumulation and the core pyrabactin resistance1-like (PYL)-protein phosphatase 2C (PP2C)-sucrose non-fermenting1-related protein kinase 2 (SnRK2) signaling module, which drives stomatal closure and downstream osmotic adjustment. In floricultural crops, these conserved pathways are further intertwined with ornamental quality-related processes such as flower pigmentation, vase life, and postproduction shelf life. Key transcription factors including CmHSFA4, RcMYB8, RcNAC091, LlHsfA2, and LlHSFA4 have been identified as central regulators of stress tolerance in these crops. Understanding these mechanisms provides a foundation for developing stress-tolerant floricultural cultivars capable of maintaining both productivity and ornamental quality under future climate scenarios.

Introduction
Molecular Mechanisms of Heat StressResponse
    Heat stress perception
    The HSF-HSP signaling cascade
    ROS accumulation and antioxidant defense
Molecular Mechanisms of DroughtStress Response
    Drought stress perception and ABA biosynthesis
    ABA core signaling: the PYL-PP2C-SnRK2 module
    Downstream drought tolerance mechanisms
Heat and Drought Stress Responsesin Floricultural Crops
    Chrysanthemum
    Rose
    Lily
    Petunia
Conclusion
Acknowledgments
References

• Suejin Park(Department of Horticulture, Jeonbuk National University, Jeonju 54896, Korea, Institute of Agriculture Science & Technology, Jeonbuk National University, Jeonju 54896, Korea) Corresponding author