Physiological and molecular responses of different rose (Rosa hybrida L.) cultivars to elevated ozone levels

The increasing ground-level ozone (O-3) pollution resulting from rapid global urbanization and industrialization has negative effects on many plants. Nonetheless, many gaps remain in our knowledge of how ornamental plants respond to O-3. Rose (Rosa hybrida L.) is a commercially important ornamental plant worldwide. In this study, we exposed four rose cultivars ("Schloss Mannheim," "Iceberg," "Luye," and "Spectra") to either unfiltered ambient air (NF), unfiltered ambient air plus 40 ppb O-3 (NF40), or unfiltered ambient air plus 80 ppb O-3 (NF80). Only the cultivar "Schloss Mannheim" showed significant O-3-related effects, including foliar injury, reduced chlorophyll content, reduced net photosynthetic rate, reduced stomatal conductance, and reduced stomatal apertures. In "Schloss Mannheim," several transcription factor genes-HSF, WRKY, and MYB genes-were upregulated by O-3 exposure, and their expression was correlated with that of NCED1, PP2Cs, PYR/PYL, and UGTs, which are related to ABA biosynthesis and signaling. These results suggest that HSF, WRKY, and MYB transcription factors and ABA are important components of the plant response to O-3 stress, suggesting a possible strategy for cultivating O-3-tolerant rose varieties.