Drought stress imposes oxidative damage on plants, yet the tissue-specific roles of salicylic acid (SA) in modulating phenolic metabolism remain poorly understood in woody species. Using Ilex rotunda seedlings, we investigated whether exogenous SA (100 µM) mitigates drought-induced oxidative damage and reshapes phenolic profiles in different tissues. Drought alone increased leaf total phenolics by 32% but depleted root phenolics by 29%, whereas combined drought + SA (DSA) treatment partially restored root phenolic levels, coinciding with elevated malondialdehyde (MDA) (2.2-fold in leaves, 2.6-fold in roots) and H₂O₂. Leaf antioxidant capacity increased under drought (DPPH by 73%, •OH by 33%), whereas root DPPH declined by 27% despite a 26% rise in •OH scavenging. SA alone induced mild oxidative responses and selectively upregulated caffeoylquinic and galloyl derivatives, notably 1-Caffeoylquinic acid (log₂FC = 6.38) in leaves. DSA treatment mitigated oxidative damage—reducing leaf MDA by 44% and root H₂O₂ by 38%. Metabolomics revealed tissue-specific reprogramming leaves accumulated dicaffeoylshikimic acid (log₂FC = 10.66) and trilobatin D (log₂FC = 11.18) under DSA, whereas roots showed contrasting patterns with up-accumulation of vanillate (log₂FC = 5.77) and suppression of 3,5-dicaffeoylquinic acid (log₂FC = −7.21) under drought, with stronger metabolic reprogramming in leaves than roots. Our findings indicate that SA-mediated drought tolerance is associated with tissue-specific phenolic reprogramming, identifying candidate indicators that advance the mechanistic understanding of woody plant resilience to drought. These results provide a framework for translating metabolomic signatures into practical strategies for stress mitigation in medicinal perennials facing climate change.

Ilex vomitoria Ait. is a star substitute for “tea” in recent years. At present, research on I. vomitoria mainly focuses on its breeding and cultivation, and there are few reports on the seasonal changes of important components such as leaf nutrients. This study focuses on the leaves of the topmost annual branches of I. vomitoria. Leaves were harvested at different stages, and the nutrient elements, antioxidant substances, antioxidant capacity, and aroma components in the leaves were measured and analyzed. The results showed that the content of mineral elements, soluble sugars, vitamin C, amino acids, flavonoids, polyphenols, saponins, caffeine, and catechins, as well as the DPPH free radical scavenging ability, ABTS cation free radical scavenging ability, and FRAP iron ion reduction ability in the leaves of I. vomitoria showed significant differences with seasonal changes. The mineral element content in spring leaves is relatively high. Flavonoids and polyphenols are the main antioxidant substances in the leaves of I. vomitoria, indicating that the antioxidant capacity of spring leaves is the strongest. The content of aroma components in the leaves of I. vomitoria in spring is the highest, with alcohols ranging from 54.93% to 66.08%, followed by ketones from 17.63% to 48.07%, and aldehydes from 21.27% to 38.51%. Overall, spring leaves are more suitable for harvesting, development, and utilization.

Cryptomeria japonica var. sinensis Miquel (Chinese cedar) is an ecologically and economically vital evergreen conifer endemic to China. Renowned for its rapid growth and superior timber quality, the species has evolved from a traditional forestry resource into a multifaceted model species for phytochemistry and biotechnology. This review synthesizes recent advancements in its biology, chemical profiling, industrial utilization, and molecular breeding. Taxonomically and morphologically distinct from the Japanese variety, Chinese cedar exhibits robust physiological plasticity and complex transcriptomic responses to abiotic stresses. Phytochemically, the tree is a prolific reservoir of volatile essential oils, complex terpenoids, and flavonoids. These bioactive secondary metabolites demonstrate potent antimicrobial, antioxidant, and neuroprotective properties, driving broad applications in modern pharmacology and sustainable agrochemicals. Industrially, the timber is increasingly utilized in the fabrication of advanced engineered structural composites and circular bioenergy production. Concurrently, breakthrough biotechnological platforms including a chromosome-level reference genome assembly, multi-omics, somatic embryogenesis, and CRISPR/Cas9-mediated genome editing have advanced molecular breeding, accelerating the targeted development of climate-resilient and non-pollen-producing (hypoallergenic) elite cultivars. However, as global climate change and historical habitat fragmentation severely threaten ancient wild populations, this review advocates for integrated in situ and ex situ conservation strategies. By identifying critical research gaps in translational pharmacology, precision gene editing, and comparative genomics, this review provides a comprehensive foundation for understanding the biology, phytochemistry, biotechnology, and utilization of this invaluable botanical resource, offering a strategic roadmap for its sustainable management and commercial valorization.

Chinese hickory (Carya cathayensis Sarg.) is a significant woody oil tree species indigenous to China; nevertheless, excessive nitrogen (N) application has emerged as a primary limiting factor for sustainable production, as it induces leaf damage, metabolic imbalance, and premature senescence. α-Ketoglutarate (α-KG), an intermediate of the tricarboxylic acid (TCA) cycle, plays a crucial role in coordinating carbon (C) and N metabolism by providing carbon skeletons for N assimilation. In this study, one-year-old C. cathayensis seedlings were subjected to the following treatments: water control (CK), α-KG alone (40 mg/L, KG3), high urea (0.8%, U), and sequential applications of urea combined with 10, 20, or 40 mg/L α-KG (UKG1–UKG3). Photosynthetic characteristics, antioxidant responses, C–N metabolic parameters, and mineral element contents were evaluated at 0, 4, 8, and 12 weeks after treatment. High-concentration urea application led to visible leaf scorching and curling. At week 8, the urea-only treatment showed no significant difference from the water control in the six OJIP parameters; however, exogenous α-KG application significantly influenced the PSII fluorescence parameters of urea-treated seedlings. Compared with U, UKG3 markedly enhanced PSII performance, with the PI_ABS value rising to 0.614 ± 0.093 (approximately 6.4 times that of U). Although urea treatment increased chlorophy ll content and net photosynthetic rate (Pn), these responses were not accompanied by a significant improvement in PSII photochemical efficiency relative to CK, indicating an imbalance between carbon assimilation and photosynthetic electron utilization under high urea supply. α-KG supplementation also improved nitrogen assimilation-related enzyme activities. GS activity under UKG treatments reached a level comparable to that of KG3. NR activity under UKG treatments decreased compared with both U and KG3 but remained higher than that of CK. α-KG alone enhanced photosynthetic performance, carbon accumulation, GS/Fd-GOGAT activities, and leaf Fe concentration without causing visible stress symptoms. Overall, exogenous α-KG supplementation partially alleviated high-urea-induced physiological disturbances in C. cathayensis seedlings, which was associated with improved PSII function and a more balanced regulation of C–N metabolism. These findings provide physiological evidence supporting the potential application of α-KG in optimizing nitrogen management strategies for C. cathayensis cultivation.