Integrated Physiological and Transcriptomic Profiling Reveals Transcriptional Signatures of Heat Tolerance in Anthurium andraeanum

Anthurium andraeanum is widely cultivated as an ornamental plant; however, high temperature (HT) stress severely restricts its growth and reduces spathe quality. To investigate the molecular basis of cultivar-specific thermotolerance, we integrated physiological and transcriptomic analyses to compare an HT-tolerant cultivar (Menghuan, MH) and an HT-sensitive cultivar (Kentucky, Ken). Under HT conditions, MH exhibited only mild color fading of spathes and slight scorching at the tips of young leaves and spathes, while Ken showed severe leaf tip scorching and spathe dehydration. Additionally, MH exhibited higher superoxide dismutase (SOD) activity and proline levels, more stable peroxidase (POD) activity and soluble protein (SP) content, and lower malondialdehyde (MDA) levels than Ken, indicating reduced lipid peroxidation and distinct antioxidant responses. RNA sequencing of leaves identified 11,901 differentially expressed genes (DEGs) across treatments. Cultivar-specific DEGs in MH were predominantly enriched in starch and sucrose metabolism and phenylpropanoid biosynthesis, whereas Ken-specific DEGs were mainly associated with the hormone signaling pathway. Weighted gene co-expression network analysis (WGCNA) identified four modules strongly correlated with HT conditions, from which several candidate hub genes were highlighted. In addition, heat shock factors and heat shock proteins showed differential induction patterns across cultivars, with earlier activation observed in MH. Together, these findings provide a comparative transcriptional framework for understanding heat stress responses in A. andraeanum and identify candidate pathways potentially underlying cultivar-specific thermotolerance.