Waterlogging adaptation in tea through hypoxia signaling and metabolic reprogramming

Waterlogging is an increasingly important climate-driven constraint threatening sustainable tea ( Camellia sinensis L.) production in humid and high-rainfall regions. Although tea requires adequate soil moisture, prolonged flooding induces rhizospheric hypoxia that severely disrupts root function, energy metabolism, and plant productivity. Oxygen deprivation suppresses mitochondrial respiration and ATP generation, leading to oxidative stress, metabolic dysfunction, impaired nutrient acquisition, and reduced photosynthetic carbon assimilation. Recent physiological, transcriptomic, and metabolomic studies have revealed extensive hypoxia-induced metabolic reprogramming involving anaerobic fermentation, reactive oxygen species (ROS) signaling, antioxidant defense activation, hormonal crosstalk, and ERF-VII-mediated oxygen-sensing pathways. These responses enhance short-term survival but frequently compromise growth, source–sink regulation, and secondary metabolism. Waterlogging also alters carbon–nitrogen balance and suppresses biosynthesis of quality-associated metabolites, including catechins, caffeine, theanine, flavonoids, and volatile aroma compounds, resulting in reduced tea quality and market value. This review synthesizes current advances in understanding the physiological, biochemical, and molecular mechanisms underlying waterlogging adaptation in tea, with particular emphasis on hypoxia signaling, metabolic reprogramming, and physiological plasticity. Furthermore, we discuss emerging climate-resilient strategies, including drainage engineering, rhizosphere management, biostimulants, flood-tolerant germplasm, genomics-assisted breeding, and precision agriculture technologies. Integrating mechanistic insights with adaptive management approaches will be critical for improving flood resilience and sustaining tea productivity and quality under future climate change scenarios.