Boron effectuation on barley (Hordeum vulgare) growth, metabolomics, protein profile, and antioxidant system during seedling growth stage

Boron is an essential micronutrient that plays a critical role in plant growth, development, and metabolic regulation. Its optimal concentration range is narrow; both deficiency and toxicity can negatively impact crop performance. Understanding its complicated impact, on barley (Hordeum vulgare), during the seedling stage is vital for elucidating its effects on growth dynamics, metabolic pathways, protein expression, and antioxidant defense mechanisms is significant. In this study, the effects of boron stress on the growth, metabolic profile, protein expression, and antioxidant system of barley (Hordeum vulgare L.) seedlings were systematically investigated. Seedlings were exposed to a range of boron concentrations (0.0, 0.4, 0.6, 0.8, and 1 mM) for 11 days, enabling a comprehensive assessment of boron's impact on morphological, physiological, and biochemical parameters critical to early plant development. Data obtained revealed that elevated boron levels, particularly at 0.8 and 1.0 mM, induced pronounced morphological and physiological damage, including yellowing, leaf curling, and stunted root and shoot growth. Growth parameters and cellulose content declined across all boron treatments, with the most severe reductions observed at the highest concentrations. These effects were accompanied by decreases in root soluble protein, total protein, and shoot proline content. Free and bound phenol contents generally declined, except at 1.0 mM, where an increasing trend was detected. Antioxidant enzyme activities, specifically catalase and peroxidase, were diminished at 1.0 mM boron, and isozyme profiles revealed marked variations between the control and high boron treatment. Protein profiling indicated overall similarity between control and 1.0 mM treatments, except for the presence of a 12 kDa band in the control and a 20 kDa band unique to the 1.0 mM boron concentration. These findings highlight the detrimental effects of excessive boron on barley growth and metabolism during the seedling stage.