Mechanisms of root system adaptation to hypoxic stress in Arabidopsis

拟南芥根系适应低氧胁迫的机制

• 批准号: 415031136
• 负责人: Professorin Dr. Jennifer Selinski, since 7/2023
• 金额: --
• 依托单位: Botanisches Institut und Botanischer Garten
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/415031136?language=en
• 关键词: Mechanisms; root; system; adaptation; hypoxic

Plants are aerobic organisms. Oxygen shortage is a constraint because it prevents mitochondrial respiration, a major source of the universal energy unit ATP. Soil waterlogging and flooding are common causes of oxygen shortage and hence of energy restriction in roots. Growth requires energy and can be limited by energy supply. However, using the model plant Arabidopsis thaliana, we recently revealed that oxygen shortage does not simply result in root growth inhibition but in controlled reshaping of the root system. The primary root changes its growth direction when exposed to hypoxia, most likely to escape to better aerated soil layers. Molecular analysis revealed that root bending is controlled by the transcription factor RAP2.12, a member of group VII Ethylene Response Factors (ERFVII) that act as oxygen sensors in plants. At the primary root tip, RAP2.12 reduces the protein level of PIN2, a polar auxin transporter, and increases local auxin activity thereby modulating the degree of root bending. We further showed that lateral roots undergo a transient growth arrest after emergence from the maternal root during the first days of hypoxia after which they resume growth. Rescue of lateral root elongation is dependent on ERFVIIs and appears to be controlled through changes in abscisic acid levels that transiently decline due to elevated expression of abscisic acid-8’-hydroxylase genes. Altered primary root growth direction and delayed lateral root growth contribute to an overall altered root system architecture as a result of low oxygen stress. From these findings, it has become clear that root system development is actively controlled during, and despite of, oxygen shortage with ERFVIIs as key regulators. Auxin and abscisic acid are targets of ERFVIIs indicating that low oxygen signaling taps into hormonal pathways for developmental reprogramming of the root system. While we have identified some of the key players, we still need to elucidate in more detail the molecular mechanisms underlying root bending and lateral root elongation. For instance, we need to understand how PIN2 abundance and auxin distribution are altered by RAP2.12. What are the primary target genes of ERFVIIs that alter root development? And there is a need to evaluate the impact of root system architecture on flooding tolerance in the long term. This project aims to address these issues and will contribute to uncover the molecular mechanisms of root system development in response to oxygen shortage.

植物是需氧生物。缺氧是一种限制，因为它阻止了线粒体呼吸，这是通用能量单位ATP的主要来源。土壤内涝和水淹是氧气短缺的常见原因，因此限制了根系的能量。增长需要能源，并可能受到能源供应的限制。然而，利用模式植物拟南芥（Arabidopsis thaliana），我们最近发现缺氧不仅会导致根系生长抑制，还会导致根系的受控重塑。初生根在缺氧条件下改变生长方向，最有可能逃到通气较好的土层。分子分析表明，根弯曲受转录因子RAP2.12控制，RAP2.12是VII组乙烯响应因子（ERFVII）的成员，在植物中起氧气传感器的作用。在初根尖，RAP2.12降低了极性生长素转运体PIN2的蛋白水平，增加了局部生长素活性，从而调节了根的弯曲程度。我们进一步发现，在缺氧的第一天，侧根从母根萌发后会经历短暂的生长停滞，之后它们会恢复生长。侧根伸长的恢复依赖于erfvii，似乎是通过脱落酸水平的变化来控制的，由于脱落酸-8 ' -羟化酶基因的表达升高，脱落酸水平会短暂下降。低氧胁迫导致主根生长方向的改变和侧根生长的延迟导致根系结构的整体改变。从这些发现可以清楚地看出，尽管缺氧，但在erfvis作为关键调节因子的情况下，根系发育受到积极控制。生长素和脱落酸是erfvis的靶标，表明低氧信号通过激素途径进入根系发育重编程。虽然我们已经确定了一些关键因素，但我们仍然需要更详细地阐明根弯曲和侧根伸长的分子机制。例如，我们需要了解RAP2.12如何改变PIN2丰度和生长素分布。erfvii改变根发育的主要靶基因是什么？有必要评估根系结构对长期耐涝能力的影响。本项目旨在解决这些问题，并将有助于揭示根系发育在缺氧条件下的分子机制。