Physiological and molecular responses of urban ornamental plants to heat stress

Abstract

Climate change remains one of the major challenges facing society, and projections indicate that its impact will intensify in the coming decades. Among the abiotic factors most affected by climate change, temperature increases are particularly concerning, causing damages to humans, animals, and plants. In addition to sustainable practices targeting climate mitigating, several strategies have been developed to reduce its impacts and enhance environmental resilience. In this context, urban green infrastructure plays a crucial role by providing shading, reducing urban heat island effects. However, the effectiveness of these green spaces largely depends on the appropriate selection of ornamental plant species, particularly those exhibiting tolerance or resilience to heat stress. Therefore, a comprehensive understanding of plant responses to elevated temperatures is essential, including physiological adaptations, morphological alterations, and molecular mechanisms. These mechanisms involve the regulation of plant hormones, transcription factors, reactive oxygen species (ROS), epigenetic modifications, and other processes associated with thermotolerance. This review systematically synthesized the available literature through searches conducted in the Scopus and Web of Science databases, using predefined keywords. Eligible studies were selected according to predefined eligibility criteria and subsequently assessed for study quality before data synthesis. Knowledge regarding heat stress responses remains limited especially in ornamental species used in urban landscapes. Significant gaps persist in understanding the physiological and molecular mechanisms underlying heat tolerance and resilience in ornamental plants. Expanding comparative studies involving a wider range of species will support the identification of thermotolerance markers, supporting selection and breeding of climate resilient genotypes for sustainable urban landscape planning. Ultimately, integrating these advances into the selection of species and cultivars will contribute to the establishment of more resilient green spaces, reducing maintenance requirements, while enhancing the sustainability and functionality of urban green infrastructure.