LAUSR

Despite the demonstration that proline accumulation and gene expression of Δ1-pyrroline-5-carboxylate synthase (p5cS) increased under osmotic stress, the impact of excess boron on proline metabolism is not well known. Therefore, we investigated the effect of different boron concentrations (10, 50, 70, 140 and 200 ppm) on seedlings root growth, lipid peroxidation rate, antioxidant enzyme activity (glutathione reductase (GR), ascorbate peroxidase (APX), catalase (CAT)), proline accumulation and transcription level of p5cS gene in Triticum aestivum L. AK-702. It was observed that seed germination and root growth in T. aestivum decreased depending on the concentration of boron. Our results indicated that boron toxicity induced lipid peroxidation and decreased GR activity under a high concentration of boron. However, the APX activity did not significantly change under high concentrations of boron (70, 140 and 200 ppm), while it increased under the lower levels of boron (10 and 50 ppm). In addition, excess boron enhanced CAT activity in the 200 ppm boron treated groups. Proline accumulation increased 2.25 and 1.45 fold in the 140 and 200 ppm boron applications. In addition, analyses of the mRNA transcription level using the semi-quantitative RTPCR results showed that excess boron increased the p5cS mRNA transcript levels and showed a positive correlation of these levels with proline accumulation in T. aestivum roots.