Cadmium (Cd²⁺) is a non-essential and highly toxic element to all organic life forms, including plants and humans. In response to Cd stress, plants have evolved multiple protective mechanisms, such as Cd²⁺ chelation, vesicle sequestration, the regulation of Cd²⁺ uptake, and enhanced antioxidant defenses. When Cd²⁺ accumulates in plants to a certain level, it triggers a burst of reactive oxygen species (ROS), leading to chlorosis, growth retardation, and potentially death. To counteract this, plants utilize a complex network of enzymatic and non-enzymatic antioxidant systems to manage ROS and protect cells from oxidative damage. This review systematically summarizes how various elements, including nitrogen, phosphorus, calcium, iron, and zinc, as well as phytohormones such as abscisic acid, auxin, brassinosteroids, and ethylene, and signaling molecules like nitric oxide, hydrogen peroxide, and hydrogen sulfide, regulate the antioxidant system under Cd stress. Furthermore, it explores the mechanisms by which exogenous regulators can enhance the antioxidant capacity and mitigate Cd toxicity.

The precise control of free auxin (indole-3-acetic acid, IAA) gradient, which is orchestrated by biosynthesis, conjugation, degradation, hydrolyzation, and transport, is critical for all aspects of plant growth and development. Of these, the GRETCHEN HAGEN 3 (GH3) acyl acid amido synthetase family, pivotal in conjugating IAA with amino acids, has garnered significant interest. Recent advances in understanding GH3-dependent IAA conjugation have positioned GH3 functional elucidation as a hot topic of research. This review aims to consolidate and discuss recent findings on (i) the enzymatic mechanisms driving GH3 activity, (ii) the influence of chemical inhibitor on GH3 function, and (iii) the transcriptional regulation of GH3 and its impact on plant development and stress response. Additionally, we explore the distinct biological functions attributed to IAA-amino acid conjugates.

Camel poll gland tissues (PGs) secrete amber liquid and volatile substances during the breeding season, inducing estrus and mating in female camels. These processes are mainly regulated by steroid hormones and their receptors, including the Androgen Receptor (AR). However, the functional components of PGs and their regulatory mechanisms in camel reproduction remain unclear. Therefore, in this study, we identified candidate differentially expressed metabolites (DEMs) and differentially expressed proteins (DEPs) associated with steroids through a multi-omics analysis of PGs during the male camel breeding season. We found that total cholesterol and testosterone concentrations were significantly increased in camel PGs at different stages of the breeding season. DEMs and DEPs related to cholesterol or steroids were analyzed using metabolomics and data-independent acquisition proteomics in the PGs of male Bactrian camels at different stages (early and peak breeding seasons), and the potential mechanism of steroid hormone synthesis was further explored. The metabolomics results identified 13 DEMs related to steroids in PGs at different stages. The proteomics results revealed seven GO terms and 69 DEPs related to steroids, with apolipoprotein E (APOE) identified as the core DEP. Pathway analysis confirmed that APOE and related DEPs were involved in cholesterol and steroid hormone synthesis. Immunostaining showed that APOE and AR were co-localized in the cytoplasm of acinar epithelial cells, and exhibited opposite expression trends in PGs during different breeding stages. These findings demonstrate that APOE- and AR-mediated cholesterol metabolism plays an important role in steroid hormone synthesis during camel reproductive activity, providing valuable insights into the mechanisms of steroid synthesis in PGs. This study offers a theoretical framework for understanding camel reproductive biology, particularly the interplay between APOE and AR in regulating cholesterol metabolism and steroidogenesis.

The poll gland, a specialized tissue of male Bactrian camels, undergoes seasonal enlargement and marked metabolic activation during the rutting season. However, the metabolic mechanisms of the poll gland and its role in rutting activities and inducing estrus are still not fully understood. This study aimed to investigate the contribution of fatty acid metabolic pathways, specifically those mediated by carnitine palmitoyltransferase 1A (CPT1A), in poll gland activity during the breeding season; poll gland tissue, neck mane, and urine samples were systematically collected from healthy male Bactrian camels stratified into breeding and non-breeding season groups for integrated proteomic, metabolomic, and biochemical assays. Histological and immunohistochemical analyses revealed reduced adipocytes but elevated ATP production in rutting camels, suggesting increased mitochondrial activity and enhanced oxidative phosphorylation. Proteomic analyses identified 119 differentially expressed proteins (DEPs) linked to fatty acid metabolism, with CPT1A, a key regulator of mitochondrial fatty acid oxidation, emerging as a central hub. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis further confirmed enrichment in fatty acid biosynthesis, degradation, and PPAR/AMPK signaling. The metabolomic analysis identified 14 metabolites, including acetylcarnitine and glycine, that were closely correlated with CPT1A expression, suggesting their potential involvement in regulating fatty acid metabolism during the breeding season. Quantitative expression analyses revealed that CPT1A in glandular acini was significantly upregulated in the breeding group compared to the non-breeding group across all assays: qPCR (2.53-fold, p < 0.05), Western blot (3.5-fold, p < 0.05), and immunohistochemistry (1.5-fold, p < 0.05). This demonstrated that CPT1A-mediated fatty acid metabolism plays a pivotal role in energy provision for reproductive activities. The results suggested that CPT1A-mediated fatty acid oxidation sustains poll gland function and reproductive behaviors in male Bactrian camels. This study provided a theoretical basis for understanding the role of CPT1A-mediated fatty acid oxidation in maintaining poll gland function and supporting reproductive activities in male Bactrian camels.