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<p>In plasma membranes, the generation of reactive oxygen species (ROS) is primarily mediated by the activation of NADPH oxidases (NOXs). This study investigated the role of NOX-derived ROS in the germination of <i>Melanoxylon brauna</i> under optimal (25&#xa0;°C) and heat stress (40&#xa0;°C) conditions. Seeds were treated with diphenyleneiodonium (DPI), a NOX inhibitor, and evaluated after 48 and 96&#xa0;h for germination rate, germination speed index, internal anatomy, hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) content, and the activity of amylases and antioxidant enzymes. Internal anatomical changes were examined by light microscopy, whereas H<sub>2</sub>O<sub>2</sub> levels and enzyme activities were determined spectrophotometrically. Under optimal conditions, DPI treatment reduced germination rate and speed by 27% and 35.4%, respectively, and hindered seed coat loosening. In addition, DPI lowered H<sub>2</sub>O<sub>2</sub> content and suppressed both amylase and antioxidant enzyme activities. Under heat stress, seeds failed to germinate regardless of treatment; however, ROS inhibition further decreased H<sub>2</sub>O<sub>2</sub> levels and reduced the activities of superoxide dismutase and ascorbate peroxidase. Collectively, these results indicate that in <i>M. brauna</i>, heat stress is the dominant factor impairing germination, and inhibition of NOX-derived ROS does not mitigate—and may even aggravate—the deleterious effects of elevated stress.</p>

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Role of NADPH oxidase-derived reactive oxygen species in Melanoxylon brauna germination under heat stress

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月30日

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  • Luciane Pereira Reis,
  • Genaina Aparecida de Souza,
  • Eduardo Euclydes de Lima e Borges,
  • Renan dos Santos Araújo

摘要

In plasma membranes, the generation of reactive oxygen species (ROS) is primarily mediated by the activation of NADPH oxidases (NOXs). This study investigated the role of NOX-derived ROS in the germination of Melanoxylon brauna under optimal (25 °C) and heat stress (40 °C) conditions. Seeds were treated with diphenyleneiodonium (DPI), a NOX inhibitor, and evaluated after 48 and 96 h for germination rate, germination speed index, internal anatomy, hydrogen peroxide (H2O2) content, and the activity of amylases and antioxidant enzymes. Internal anatomical changes were examined by light microscopy, whereas H2O2 levels and enzyme activities were determined spectrophotometrically. Under optimal conditions, DPI treatment reduced germination rate and speed by 27% and 35.4%, respectively, and hindered seed coat loosening. In addition, DPI lowered H2O2 content and suppressed both amylase and antioxidant enzyme activities. Under heat stress, seeds failed to germinate regardless of treatment; however, ROS inhibition further decreased H2O2 levels and reduced the activities of superoxide dismutase and ascorbate peroxidase. Collectively, these results indicate that in M. brauna, heat stress is the dominant factor impairing germination, and inhibition of NOX-derived ROS does not mitigate—and may even aggravate—the deleterious effects of elevated stress.