Determining mechanisms of phloem formation

韧皮部组织是在植物体内运输有机物质（包括碳水化合物、激素和其他信号分子）的主要通道。由于韧皮部在植物生长和生理中的核心作用，近年来，韧皮部已成为植物组织形成的典范。先前，我们发现MAX2 1-LIKE 3 (SMXL3)， SMXL4和SMXL5蛋白的核抑制因子是韧皮部形成的关键调控因子，可能是通过建立韧皮部特异性染色质谱在早期阶段起作用。然而，对SMXL蛋白的分子作用的了解仍然有限，包括它们对核特征、蛋白质结合伙伴和假定的基因靶点的影响。在这个项目的背景下，我们将集中研究SMXL5的作用，假设SMXL5在未来韧皮部细胞的细胞核中形成蛋白质复合物，建立韧皮部形成所必需的染色质特征。我们将通过鉴定植物中的相互作用蛋白并验证这些相互作用的相关性，以及揭示组织特异性染色质特征及其对smxl5相关蛋白的依赖性来验证这一假设。按照这个策略，该项目利用SMXL5功能的高指导性读出，并结合了正交生化和遗传实验方法的优点。因此，我们期望，该项目不仅将加深我们对组织规格调节原理的理解，而且还将揭示一组有趣的发育调节因子的作用模式。

The phloem tissue is the main conduit for transporting organic matter including carbohydrates, hormones and other signaling molecules throughout the plant body. Driven by this central role for plant growth and physiology, the phloem has emerged in recent years as a paradigm for plant tissue formation. Previously, we discovered that the nuclear SUPPRESSOR OF MAX2 1-LIKE 3 (SMXL3), SMXL4 and SMXL5 proteins are key regulators of phloem formation acting at early stages, presumably, by establishing a phloem-specific chromatin profile. However, insight into the molecular role of SMXL proteins is still limited including knowledge of their effect on nuclear signatures, protein binding partners and putative gene targets. In the context of this project, we will concentrate on the role of SMXL5 hypothesizing that SMXL5 forms protein complexes in nuclei of future phloem cells establishing chromatin signatures essential for phloem specification. We will test this hypothesis by identifying interacting proteins in planta and verifying the relevance of these interactions, and by revealing tissue-specific chromatin signatures and their dependence on SMXL5-associated proteins. Following this strategy, the project makes use of highly instructive read-outs for the SMXL5 function and combines the benefits of orthogonal biochemical and genetic experimental approaches. We expect that, thereby, the project will not only deepen our understanding of the regulatory principles of tissue specification but also reveal the action mode of a group of intriguing developmental regulators.