Understanding the role of chromatin modifying complexes in the abiotic stress response mechanisms of cereal plants

植物经常暴露在它们必须适应的环境压力下（如低温）。这些应激调节了参与应激反应机制的重叠基因组的表达。我们的长期目标是了解控制谷物非生物胁迫耐受性等重要农艺性状的染色质机制。我们假设除了转录元件的作用外，染色质在感知压力时的动态调节是适应所必需的主要调节机制。为了实现这一目标，我们将利用我们的第一笔NSERC发现基金所产生的知识和动力。在2015-2020年的资助期内，我们将重点关注3个新的目标：1)确定春季、兼性和冬季短茅属植物的冷驯化参数，以获得最佳的抗冻性发展。我们已经确定了常用的7种材料要么是兼性的，要么是冬季的习惯。然而，现在有超过180个二倍体材料，为我们提供了发现真正具有春季（敏感）和冬季（耐受）习性的材料的机会。这将使我们能够进行功能比较分析；2)表征BdADA2在低温染色质动力学中的作用。已知saga靶向基因受应激调节，我们已经在植物中发现该复合物的一个重要组成部分ADA2与CBF1相互作用。我们已经产生了过表达ADA2的Brachypodium转基因系。这些细胞系GCN5靶向的H3赖氨酸乙酰化增加，一些COR基因的表达减少。这些细胞系将用于提供证据，证明CBF1和ADA2之间的相互作用可能代表冷硬化转录和染色质调节反应之间的整合节点；3)表征DNA甲基化在短柄草冷硬化过程中的作用。DNA甲基化被认为在谷物的冷驯化反应中起主导作用。我们已经建立了该途径的几个关键基因：DRM2、CMT3和AGO4的短柄基敲低和过表达系。我们将把这些品系暴露在低温下，以揭示DNA甲基化在冷驯化过程中的重要性，这将精确地确定这些修饰剂在单子房中的作用。这个独特的项目旨在了解谷物中染色质对胁迫耐受性的控制，鉴于所涉及的分子电路的普遍逻辑，将对其他分类类群的表观遗传研究产生重大影响。此外，我们的研究将导致通过利用特定的染色质修饰剂进行遗传和表观遗传编辑策略来改善作物重要性状的策略的发展。随着表观遗传学对HQP需求的增加，本项目将培养3名博士、2名硕士和数名本科生。

Plants are constantly exposed to environmental stresses (e.g. low temperature) to which they must adapt. These stresses regulate the expression of overlapping suites of genes involved in stress response mechanisms. Our long-term goal is to understand the chromatin mechanisms that control agronomically important traits such as abiotic stress tolerance in cereals. We hypothesize that in addition to the role of transcriptional elements, the dynamic tuning of chromatin upon perception of stress is a major regulatory mechanism necessary for adaptation.  To achieve this goal, we will build on knowledge and momentum generated by our first NSERC Discovery grant. During the 2015-2020 funding period we will focus on 3 new objectives: 1) Determine the cold acclimation parameters of spring, facultative and winter Brachypodium accessions for optimal freezing tolerance development. We have established that the 7 accessions commonly used have either facultative or winter habits. However, more than 180 diploid accessions are now available, offering us the opportunity to uncover accessions with true spring (sensitive) and winter (tolerant) habits. This will allow us to perform functional comparative analyses; 2) Characterize the role of BdADA2 in low temperature chromatin dynamics. SAGA-targeted genes are known to be regulated by stress and we have shown in planta that an important component of this complex - ADA2 - interacts with CBF1. We have generated Brachypodium transgenic lines that overexpress ADA2. These lines have increased acetylation at the H3 lysines targeted by GCN5, as well as reduced expression of some COR genes. These lines will be used to provide evidence that the interaction between CBF1 and ADA2 potentially represents an integration node between the transcriptional and chromatin regulatory responses of cold hardening; 3) Characterize the role of DNA methylation during cold hardening in Brachypodium. DNA methylation is believe to play a predominant role in the cold acclimation response of cereals. We have generated Brachypodium knockdown and overexpression lines for several key genes of this pathway: DRM2, CMT3 and AGO4. We will expose these lines to low temperatures to reveal the importance of DNA methylation during cold acclimation, which will precise the role of these modifiers in monocots. This unique project aiming at understanding chromatin control of stress tolerance in cereals will have a major impact on epigenetic research on other taxonomic groups given the universal logic to the molecular circuitry involved. In addition, our research will lead to the development of strategies for the improvement of important traits in crops by harnessing specific chromatin modifiers for genetic and epigenetic editing strategies. In line with the increasing need for HQP in epigenetics, this project will train 3 PhD, 2 MSc and several undergraduate students.