biostudies-literatureUnknown12Xing XFundamental Research Funds for the Central UniversitiesChina Postdoctoral Science FoundationNational Key Research and Development Program of ChinaHeat stress limits the growth and development of chrysanthemum seedlings. Although melatonin (MT) has been linked to the heat stress response in plants, research on the underlying molecular mechanisms is scarce. In this study, the regulatory networks of MT on heat stress in chrysanthemum seedlings were explored. Physiological measurements suggested that MT not only reduced malondialdehyde accumulation, hydrogen peroxide content, and superoxide anion free radical generation rate, but also significantly promoted osmotic regulation substance synthesis (proline and soluble protein), antioxidant accumulation (GSH and AsA), and the antioxidant enzyme activities (SOD, POD, CAT, and APX) in chrysanthemum leaves under heat stress. Furthermore, MT increased the fresh weight, dry weight, chlorophyll content, photosynthesis rate, and gas exchange indexes. Further, RNA-seq results revealed 33,497 and 36,740 differentially expressed genes in the S/Con and SMT/ConMT comparisons, respectively. The differences in the comparisons revealed that MT regulated heat shock transcription factors (HSFs) and heat shock proteins (HSPs), and the genes involved in Ca²⁺ signal transduction (<i>CNGCs</i> and <i>CAM/CMLs</i>), starch and sucrose metabolism (<i>EDGL, BGLU, SuS</i>, and <i>SPS</i>), hormone (<i>PP2Cs</i>, <i>AUX/IAAs</i>, <i>EBFs</i>, and <i>MYC2</i>), chlorophyll metabolism (<i>HEMA</i> and <i>PORA</i>), flavonoid biosynthesis (<i>CHS</i>, <i>DFR</i>, and <i>FNS</i>), and carotenoid biosynthesis (<i>DXPS</i>, <i>GGDP</i>, and <i>PSY</i>). MT effectively improved chrysanthemum seedling heat-resistance. Our study, thus, provides novel evidence of a gene network regulated by MT under heat stress.Frontiers in plant science673236https://www.ebi.ac.uk/biostudies/studies/S-EPMC8493036biostudies-literaturePhysiological and Transcripts Analyses Reveal the Mechanism by Which Melatonin Alleviates Heat Stress in Chrysanthemum Seedlings.PMC8493036Jiang JDing YFang WXing XSong AChen FChen SJin JfalsePhysiological and Transcripts Analyses Reveal the Mechanism by Which Melatonin Alleviates Heat Stress in Chrysanthemum Seedlings.Heat stress limits the growth and development of chrysanthemum seedlings. Although melatonin (MT) has been linked to the heat stress response in plants, research on the underlying molecular mechanisms is scarce. In this study, the regulatory networks of MT on heat stress in chrysanthemum seedlings were explored. Physiological measurements suggested that MT not only reduced malondialdehyde accumulation, hydrogen peroxide content, and superoxide anion free radical generation rate, but also significantly promoted osmotic regulation substance synthesis (proline and soluble protein), antioxidant accumulation (GSH and AsA), and the antioxidant enzyme activities (SOD, POD, CAT, and APX) in chrysanthemum leaves under heat stress. Furthermore, MT increased the fresh weight, dry weight, chlorophyll content, photosynthesis rate, and gas exchange indexes. Further, RNA-seq results revealed 33,497 and 36,740 differentially expressed genes in the S/Con and SMT/ConMT comparisons, respectively. The differences in the comparisons revealed that MT regulated heat shock transcription factors (HSFs) and heat shock proteins (HSPs), and the genes involved in Ca²⁺ signal transduction (<i>CNGCs</i> and <i>CAM/CMLs</i>), starch and sucrose metabolism (<i>EDGL, BGLU, SuS</i>, and <i>SPS</i>), hormone (<i>PP2Cs</i>, <i>AUX/IAAs</i>, <i>EBFs</i>, and <i>MYC2</i>), chlorophyll metabolism (<i>HEMA</i> and <i>PORA</i>), flavonoid biosynthesis (<i>CHS</i>, <i>DFR</i>, and <i>FNS</i>), and carotenoid biosynthesis (<i>DXPS</i>, <i>GGDP</i>, and <i>PSY</i>). MT effectively improved chrysanthemum seedling heat-resistance. Our study, thus, provides novel evidence of a gene network regulated by MT under heat stress.2021-01-01T00:00:00Z20212024-11-19T15:36:42.379Z2022-02-11T12:03:50.216ZS-EPMC84930363463044610.3389/fpls.2021.673236