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，也是维持后代遗传一致性的普遍做法。随着无土基质在高通量繁殖中的使用越来越多，以及对可持续园艺措施的需求日益增长，深入了解矿质营养在AR形成中的作用对于改进现有的繁殖方案至关重要。我们以前的工作表明，铁是AR形成的最有限的营养物质，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方面具有独特的未被开发的作用，与其在分生组织细胞核中的高度积累有关。该项目旨在研究铁刺激AR形成的生理生化机制，并确定可用于促进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在施铁时的主要解剖和生理过程。使用RNAseq和基于核仁蛋白质的MS分析的全面转录组图谱将识别参与铁加速AR形成的基因和蛋白质。从蛋白质组学和转录学研究中获得的主要候选基因的功能将在转座子插入或CRISPR/Cas9修饰的转基因植物中利用解剖学和生理学方法进行表征。最后，为了更好地获得更多的突变体和几个园艺作物的商业品种，将在野生矮牵牛加入系、茄科密切相关属如番茄基因库中研究铁依赖AR的形成。这项研究将促进对铁在植物核仁中独特功能的理解，并将为有针对性地开发无性繁殖作物中的铁营养奠定基础。

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