Mitigating Arsenate-Induced Phytotoxicity in Fenugreek Seedlings Using Garlic Extract: Insights into Photosynthesis, Arsenate Uptake, Antioxidative Machinery and Ultrastructure

Abstract

Abstract Arsenate (As) pollution poses severe health issues due to its non-essentiality and mobility through food chains. The current investigation was conducted to study the stimulating capacity of aqueous garlic extract (AGE) to impede As toxicity in fenugreek ( Trigonella foenum-graecum L.). Gas Chromatography-Mass Spectrometry (GC/MS) analysis of AGE revealed the presence of organosulfur and phenolic compounds. The irrigation with 50 mM As hampered the morphological, physiological, and biochemical traits of fenugreek. As-induced toxicity increased levels of hydrogen peroxide (H 2 O 2 ), hydroxyl radical (OH • ) , and lipid peroxidation. The modified antioxidative machinery and increased osmolyte levels (amino acids, proline, and glycine betaine) were recorded following As application. Furthermore, As disrupted the ultrastructure of chloroplasts, mitochondria, cellular membranes, cell walls, and xylem vessels. AGE priming reduced As accumulation and restored plant growth, photosynthetic traits, and metabolic constituents. The antioxidative potential of AGE bioactive components upregulated enzymatic and non-enzymatic antioxidants and maintained the normal cell redox status of As-stressed fenugreek plants. Furthermore, AGE priming promoted superoxide dismutase (SOD) and ascorbate peroxidase (APOX) activities, limiting reactive oxygen species burst and membrane leakage. Additionally, AGE priming effectively restored normal ultrastructural compartments and cellular turgidity, preventing cell apoptotic symptoms and reducing As-induced cellular toxicity. The stimulatory potential of AGE can be assigned to its antioxidant components, which reduce oxidative stress and boost ROS detoxification mechanisms including the ascorbate–glutathione (ASA-GSH) cycle. Thus, As negatively impacted fenugreek, increased oxidative stress and disrupted cellular structures, but AGE priming countered As effects by enhancing antioxidants and cellular integrity, supporting plant recovery. Graphical Abstract

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