Dpto. de Biología Molecular, FCEFQN, Universidad Nacional de Río Cuarto, X5804BYA Río Cuarto, Córdoba, Argentina.
Dpto. de Biología Molecular, FCEFQN, Universidad Nacional de Río Cuarto, X5804BYA Río Cuarto, Córdoba, Argentina.
Plant Physiol Biochem. 2017 Apr;113:149-160. doi: 10.1016/j.plaphy.2017.02.008. Epub 2017 Feb 10.
Phospholipase D (PLD) hydrolyses phospholipids to yield phosphatidic acid (PA) and a head group, and is involved in responses to a variety of environmental stresses, including chilling and freezing stress. Barley responses to chilling stress (induced by incubating seedlings at 4 °C) are dynamic and the duration of stress, either short (0-180 min) or long-term (24-36 h) had a significant impact on the response. We investigated the roles of PLD/PA in responses of barley (Hordeum vulgare) seedlings to short and long-term chilling stress, based on regulation of proline and reactive oxygen species (ROS) levels. Short-term chilling stress caused rapid and transient increases in PLD activity, proline level, and ROS levels in young leaves. PLD has the ability to catalyse the transphosphatidylation reaction leading to formation of phosphatidylalcohol (preferentially, to PA). Pre-treatment of seedlings with 1-butanol significantly increased proline synthesis but decreased ROS (HO) formation. These observations suggest that PLD is a negative regulator of proline synthesis, whereas PA/PLD promote ROS signals. Exogenous PA pre-treatment reduced the proline synthesis but enhanced HO formation. Effects of long-term chilling stress on barley seedlings differed from those of short-term chilling stress. E.g., PLD activity was significantly reduced in young leaves and roots, whereas proline synthesis and ROS signals were increased in roots. Exogenous ROS application enhanced proline level while exogenous proline application reduced ROS level and modulated some effects of long-term chilling stress. Our findings suggest that PLD contributes to signalling pathways in responses to short-term chilling stress in barley seedling, through regulation of the balance between proline and ROS levels. In contrast, reduced PLD activity in the response to long-term chilling stress did not affect proline level. Increased ROS levels may reflect an antioxidant system that is affected by chilling stress and positively compensated by changes in proline level. Implications of our findings are discussed in regard to adaptation strategies of barley seedlings to low temperatures.
磷脂酶 D (PLD) 将磷脂水解生成磷酸脂和一个头基，参与多种环境胁迫的响应，包括冷胁迫和冻胁迫。大麦对冷胁迫（通过在 4°C 下培养幼苗来诱导）的响应是动态的，胁迫的持续时间，无论是短期（0-180 分钟）还是长期（24-36 小时），都对响应有显著影响。我们研究了 PLD/PA 在大麦幼苗对短期和长期冷胁迫响应中的作用，基于脯氨酸和活性氧（ROS）水平的调节。短期冷胁迫导致幼叶中 PLD 活性、脯氨酸水平和 ROS 水平的快速和短暂增加。PLD 能够催化转磷酸化反应，导致磷脂醇（优先形成 PA）的形成。幼苗用 1-丁醇预处理显著增加脯氨酸合成，但降低 ROS（HO）的形成。这些观察表明，PLD 是脯氨酸合成的负调节剂，而 PA/PLD 促进 ROS 信号。外源性 PA 预处理减少脯氨酸合成，但增强 HO 形成。长期冷胁迫对大麦幼苗的影响与短期冷胁迫不同。例如，PLD 活性在幼叶和根中显著降低，而脯氨酸合成和 ROS 信号在根中增加。外源 ROS 处理增强脯氨酸水平，而外源脯氨酸处理降低 ROS 水平并调节长期冷胁迫的一些影响。我们的研究结果表明，PLD 通过调节脯氨酸和 ROS 水平之间的平衡，在大麦幼苗对短期冷胁迫的响应中参与信号通路。相比之下，长期冷胁迫响应中 PLD 活性的降低并不影响脯氨酸水平。ROS 水平的增加可能反映了一种抗氧化系统，该系统受到冷胁迫的影响，并通过脯氨酸水平的变化得到积极补偿。我们的研究结果在讨论大麦幼苗适应低温的适应策略时具有重要意义。
