Integrative Physiological, Metabolomic and Transcriptomic Analyses Uncover the Mechanisms Underlying Differential Responses of Two Anubias Genotypes to Low-Temperature Stress

<i>Anubias</i> (Araceae) is a globally important group of ornamental aquatic plants. However, when temperatures drop to 10 °C, most species suffer obvious frostbite from cold stress, restricting winter cultivation and broader application. This study focused on two <i>Anubias</i> genotypes with distinct cold tolerance, adopting an integrated approach combining phenotypic, physiological, metabolomic, and transcriptomic analyses to reveal the mechanisms underlying their differential cold tolerance. Under 10 °C cold stress, compared with normal temperatures, the leaves of cold-tolerant <i>Anubias</i> sp. 'Long Leaf' (Jian) showed no significant frostbite, while cold-sensitive <i>Anubias barteri</i> var. <i>nana</i> 'Coin Leaf' (Jin) had clear frost damage. Both genotypes exhibited increased leaf relative electrical conductivity, malondialdehyde (MDA) content, soluble sugar content, and activities of superoxide dismutase (SOD) and catalase (CAT); "Jian" had more notable rises in SOD/CAT activities and maintained higher levels, whereas "Jin" showed greater increases in conductivity, MDA, and soluble sugar. Metabolomic and transcriptomic analyses revealed "Jian" specifically upregulated metabolites in pathways like flavone and flavonol biosynthesis and tryptophan metabolism, as well as genes related to valine, leucine, isoleucine degradation and phenylpropanoid biosynthesis pathways. ERFs, WRKYs, NACs and other transcription factors correlated with these differentially expressed genes, suggesting potential transcriptional regulation. These results provides insights for breeding cold-tolerant <i>Anubias</i> and optimizing low-temperature cultivation.