Deciphering molecular mechanisms controlling seed development under low energy stress

破译低能量胁迫下控制种子发育的分子机制

• 批准号: 408153945
• 负责人: Dr. Christoph Weiste
• 金额: --
• 依托单位: Julius-von-Sachs-Institut für Biowissenschaften
• 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 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/408153945?language=en
• 关键词: Deciphering; molecular; mechanisms; controlling; seed

Deciphering molecular mechanisms controlling seed development under low energy stressSummary:Seed yield is a major agronomic trait that depends on proper seed development. It is well-established that the early developmental stages, which comprise embryogenesis, are largely controlled by transcriptional regulation mediated by the phytohormone auxin. Besides this, recent studies revealed that environmental stresses that converge on energy deprivation, also exclusively interfere with early seed establishment, resulting in growth repression of siliques and seed abortion. Although this low energy stress (LES) response was characterised to be reversibly and dynamically tuned according to the plants` prevailing energy status, the underlying molecular mechanism is yet unknown.In our previous work, we unravelled that central players of the plant‘s energy management system, namely basic leucine ZIPper 11 (bZIP11) related transcription factors (TF), which are controlled by the pivotal low-energy activated Snf1 Related Protein Kinases 1 (SnRK1s) integrate low-energy related stimuli into auxin-driven meristematic growth processes. This is mechanistically accomplished by controlling expression of specific Aux/IAAs, which constitute negative feedback regulators of auxin signalling, auxin transport and in consequence auxin-driven meristem activity. As bZIP expression was found to result in strongly reduced seed set and bZIP11-related transcripts that underlie energy-dependent posttranscriptional regulation, reveal a distinct accumulation within the early ovule, we assume that a SnRK-bZIP growth regulatory system evolved to adjust auxin-mediated seed development according to the plants‘ prevailing energy reserves. Specifically operating during early and not late developmental stages, this low energy-triggered system could enable channelling of residual energy resources to nearly completed seeds, thereby ensuring survival of plant progeny under LES.To test this hypothesis, we will initially characterize starvation-responsive bZIP expression domains and kinetics throughout embryogenesis. At the defined, bZIP-controlled seed stages, we will study effects of bZIP mis-expression on the embryos’ auxin signalling and morphology under high- and low energy conditions, making use of inducible and constitutive gain- and loss-of-function approaches. The obtained results will unravel the impact of bZIP11-related TFs in starvation-responsive seed development. Finally, we will address the underlying molecular mechanisms by deciphering the transcriptional network downstream of the bZIP regulators, applying a combination of RNAseq and ChIPseq techniques. Taken together, the proposed project will provide essential insights how energy starvation is transduced into seed development. The obtained knowledge will strongly foster basic research on plant stress adaptation processes and, due to its impact on seed yield, support the development of stress tolerant crops.

破译低能量胁迫下控制种子发育的分子机制摘要：种子产量是一项主要的农艺性状，取决于种子的适当发育。众所周知，包括胚胎发生在内的早期发育阶段在很大程度上是由植物激素生长素介导的转录调控所控制的。此外，最近的研究表明，集中在能量匮乏上的环境胁迫也完全干扰了早期种子的建立，导致角果生长抑制和种子败育。虽然这种低能量胁迫(LES)响应的特点是可逆的和动态的根据植物的普遍能量状态进行调整，但潜在的分子机制尚不清楚。在我们之前的工作中，我们揭示了植物能量管理系统的核心角色，即碱性亮氨酸拉链11(BZIP11)相关的转录因子(Tf)，它受关键的低能激活的Snf1相关蛋白激酶1(SnRK1)控制，将低能量相关刺激整合到生长素驱动的分生组织生长过程中。这在机制上是通过控制特定AUX/IAA的表达来实现的，AUX/IAA构成生长素信号转导、生长素运输的负反馈调节，从而导致生长素驱动的分生组织活动。由于bZIP的表达导致种子结实率和bZIP11相关的转录本显著减少，这是能量依赖的转录后调控的基础，揭示了早期胚珠中明显的积累，我们假设SnRK-bZIP生长调控系统进化到根据植物的主要能量储备来调节生长素介导的种子发育。这个低能量触发的系统在发育的早期而不是后期运行，能够将剩余的能量资源输送到接近完成的种子，从而确保植物后代在LES下存活。为了验证这一假说，我们首先将表征饥饿响应的bZIP表达结构域和整个胚胎发生的动力学。在确定的、bZIP控制的种子阶段，我们将利用可诱导的和结构性的获得和丧失功能的方法，研究bZIP错误表达对高能量和低能量条件下胚胎生长素信号和形态的影响。所获得的结果将揭示与bZIP11相关的转录因子在饥饿反应种子发育中的影响。最后，我们将结合RNAseq和ChIPseq技术，通过破译bZIP调节器下游的转录网络来解决潜在的分子机制。综上所述，拟议的项目将提供重要的见解，如何将能源匮乏转化为种子发育。所获得的知识将有力地促进植物逆境适应过程的基础研究，并由于其对种子产量的影响，支持耐逆作物的发展。