Functional characterization of Fe-dependent mechanisms promoting the stimulation of adventitious root formation in petunia cuttings

不定根的形成是重要作物无性繁殖的先决条件，也是维持后代遗传同一性的普遍做法。随着无土培养基在高通量繁殖中的使用越来越多，以及对可持续园艺实践的需求不断增长，深入了解矿物质营养在AR形成中的作用对于改进现有的繁殖方案至关重要。我们之前的工作表明，铁是AR形成的最限制性营养物质，并提供了令人信服的证据，证明铁在刺激分生组织细胞分裂中具有独特的未开发作用，与它在分生组织细胞细胞核中的高积累有关。本项目旨在研究铁刺激AR形成的生理生化机制，并确定可用于改善AR形成的基因。首先，详细的细胞生物学分析和铁的超微结构定位将确定铁应用后的主要解剖和生理过程。使用RNAseq和基于质谱的核仁蛋白分析的综合转录组分析将识别参与铁加速AR形成的基因和蛋白质。从蛋白质组学和转录组学研究中获得的顶级候选基因的功能将通过解剖学和生理学的方法在转座子插入或CRISPR/ cas9修饰的转基因植物中进行表征。最后，将在野生矮牵牛加入系、茄科密切相关属（如番茄基因库）和几个园艺作物商业品种中研究铁依赖的AR形成，以便更好地获得额外的突变体。本研究将促进对铁在植物核仁中独特功能的认识，并为无性繁殖作物铁营养的定向开发奠定基础

Adventitious root (AR) formation is prerequisite for vegetative propagation of important crops and common practice to maintain the genetic identity among progenies. With increasing use of soil-free media in high-throughput propagation and growing demand for sustainable horticultural practices, a deep understanding of the role of mineral nutrition in AR formation is essential for the improvement of existing propagation protocols. Our previous work demonstrated that Fe is the most limiting nutrient for AR formation and provided compelling evidence for a unique unexploited role of Fe in stimulation of meristematic cell division, associated with its high accumulation in the nuclei of meristematic cells. The proposed project aims to study the physiological and biochemical mechanisms underlying Fe-stimulated AR formation and to identify genes that can be used to improve AR formation. Initially, a detailed cell biological analysis and ultrastructural localization of Fe will define the major anatomical and physiological processes upon Fe application. A comprehensive transcriptome profiling using RNAseq and MS-based analysis of nucleolar proteins will identify genes and proteins involved in Fe-accelerated AR formation. The function of top candidate genes derived from proteomic and transcriptomic studies will be characterized in transposon-insertion or CRISPR/Cas9-modified transgenic plants using anatomical and physiological approaches. Finally, the Fe-dependent AR formation will be studied in wild petunia accession lines, closely related Solanaceae genera such as tomato gene pool for a better access to additional mutants and several commercial cultivars of horticultural crops. The proposed study will advance the understanding of the unique function of Fe in the plant nucleolus and will pave the ground for a targeted exploitation of Fe nutrition in vegetative propagated crops