Tulips are a major global floricultural crop, but their greenhouse production faces challenges such as inconsistent quality and lengthy growth cycles. Hydroponics offers a controlled cultivation method, but strategies for precisely regulating development are needed. Rare earth elements like cerium (Ce) are known to exert hormetic effects, but their integrative mechanisms in ornamental plants remain unclear. This study investigated the concentration-dependent effects of Ce 3+ on hydroponically cultivated tulips (“World's Favourite”). A distinct hormetic response was observed. The 1.0 mg/L Ce 3+ treatment promoted root elongation and activity, accompanied by increased meristematic cell division and a strengthened antioxidant system, which improved ROS scavenging and redox homeostasis. This root improvement was associated with enhanced nutrient uptake. Critically, these root-mediated effects were synchronized with aerial improvements: increased leaf chlorophyll, photosynthetic performance, and petal anthocyanin content, collectively accelerating flowering and elevating cut flower quality. Transcriptomic analysis linked these coordinated changes to the upregulation of genes involved in cell cycle ( Cyclin B1-1 ), antioxidant defense (peroxidases), and phenylalanine/anthocyanin biosynthesis. We propose a dose-dependent response model where low-dose Ce 3+ is associated with a coordinated set of responses that simultaneously boosts root proliferation and floral pigment production without triggering a growth-defense tradeoff, representing a synergistic rather than competitive resource allocation. Conversely, 10.0 mg/L Ce 3+ inhibited growth, induced oxidative stress, and impaired development, reflecting a classic stress response. Our findings demonstrate that Ce 3+ dose-dependently regulates tulip growth and flowering through an integrated physiologico-molecular network, fine-tuning redox signaling, cell cycle progression, and secondary metabolism to optimize plant quality. • Ce 3+ exhibits a hormetic, concentration-dependent effect on tulip growth, with stimulation at 1.0 mg/L and inhibition at 10.0 mg/L. • Low-dose Ce 3+ is associated with ROS signaling that upregulates antioxidant enzymes and a Cyclin B1-1 homolog, enhancing root meristem activity. • This root response links to enhanced leaf photosynthesis and phenylpropanoid pathway activation, boosting petal anthocyanin content. • Gene expression analyses link specific peroxidases to ROS reduction, and phenylalanine genes to anthocyanin accumulation. • High-dose Ce 3+ induces a toxic ROS burst, represses growth genes, and activates metal detoxification (metallothioneins), halting development.
Shan et al. (Wed,) studied this question.