Physiological and Transcription Analyses Reveal the Regulatory Mechanism of Melatonin in Inducing Drought Resistance in Blueberry (Vaccinium spp.) Seedlings

Melatonin (MT) has been confirmed to relieve drought stress in various plant species. However, its action mechanism remains to be elucidated in blueberries (Vaccinium spp.). This study analyzed the protective effects and regulatory mechanisms of MT on drought stress in blueberry seedlings. The physiological analysis showed that MT effectively mitigated chlorophyll degradation and malondialdehyde accumulation in the blueberry leaves under drought stress. In addition, MT improved the antioxidant enzyme activity and soluble sugar content of blueberry seedlings. Transcriptome results suggested that MT may enhance blueberry drought tolerance by regulating the ERF and bHLH genes in the secondary metabolite pathway. These results provided a new perspective on the role of MT in drought stress and a basis for gene function analysis in MT-mediated signaling pathways.