Hosta ventricosa is a popular shade-tolerant ornamental perennial vulnerable to high light, whose molecular mechanisms of high-light stress response remain unclear. To clarify this, we measured leaf morphology, photosynthetic physiology, and performed integrated analyses using PacBio full-length and Illumina transcriptome sequencing on plants under full sunlight (FS), moderate shade (MS), and deep shade (DS) treatments. The results indicated that MS showed optimal growth, whereas FS and DS inhibited growth, each associated with distinct gene expression profiles. High light induced VDE by 5.68-fold to activate the xanthophyll cycle and repress light-harvesting complex II and ribulose-1,5-bisphosphate carboxylase/oxygenase genes, whereas deep shade inhibited the photosynthetic apparatus and triggered stress genes. In contrast, deep shade conditions suppressed the photosynthetic machinery and induced the expression of stress-related genes. This study elucidates the molecular mechanisms underlying light stress responses in H. ventricosa, providing valuable insights for future molecular breeding efforts.
Drought limits the growth of Paeonia ostii 'Fengdan'. While melatonin (MT) is known to enhance general drought tolerance, its association with Photosystem I-Photosystem II (PSI-PSII) photochemical coordination and secondary-metabolite accumulation in P. ostii remains unclear. We foliar-sprayed potted plants under simulated drought with 0, 50, 100, 200, and 400 μmol(MT) L-1. Drought induced severe oxidative damage, impaired photosynthesis, and disrupted photochemical coordination between PSI and PSII. Among all treatments, 100 μmol(MT) L-1 proved the most effective. It coincided with reduced reactive oxygen species and membrane damage, alongside increased antioxidants, osmolytes, and PSI/PSII performance. Furthermore, compared to drought alone, 100 μmol(MT) L-1 treatment increased the root-bark contents of total flavonoids, total phenolics, gallic acid, catechin, albiflorin, paeoniflorin, benzoic acid, and paeonol by 48.1, 36.1, 17.7, 69.4, 69.9, 24.1, 7.7, and 22.7%, respectively. Thus, 100 μmol(MT) L-1 alleviated drought-induced physiological damage and increased selected secondary-metabolite contents in P. ostii.
Drought constrains shrub establishment and persistence in arid and semi-arid restoration systems. Although Hippophae rhamnoides is widely planted in northern China, its drought responses vary among studies, hindering the identification of stable indicators. We synthesized 3,855 treatment-control comparisons from 49 controlled experiments across 12 Chinese provinces using random-effects meta-analysis and structural equation modeling. Results showed that drought adaptation in H. rhamnoides follows a functional cascade. Water status and membrane stability were the most consistent early constraints, followed by strong suppression of photosynthetic and gas-exchange traits. Photosynthesis acted as a key mediating factor linking water deficit, hormonal adjustment, and growth reduction. Under severe drought, membrane permeability increased by 89.5%, while leaf water content, net photosynthetic rate, transpiration rate, and stomatal conductance decreased by 37.2, 83.3, 91.2, and 92.9%, respectively. Therefore, drought evaluation should prioritize water status, membrane stability, photosynthetic performance, and growth traits.
Cadmium impairs plant growth by inducing oxidative damage through excessive ROS production. Sulfur and nitrogen supplementation can affect Cd mobility, uptake, and toxicity. This study quantifies the spatial heterogeneity of Cd-induced photochemical limitation in Solanum lycopersicum leaves using chlorophyll fluorescence imaging, and examines Cd2+ distribution in roots, stems, and leaves of hydroponic plants treated with ammonium sulfate. We assessed four treatments: control, ammonium sulfate (5 mM), cadmium (100 µM CdCl2), and their combination, using fluorescence imaging, the JIP-test, and polarography. Cd stress was intrinsically heterogeneous within single leaves, with the strongest PSII inhibition along vascular tissue and leaf tips. Contrary to expectations, ammonium sulfate failed to mitigate Cd toxicity, suggesting an adverse ammonium-Cd interaction. OJIP analysis revealed severe oxygen-evolving complex damage under combined treatment, marked by prominent K- and L-bands. These findings highlight the localised nature of Cd stress and reveal responses missed by whole-leaf measurements.
