Genetic and Molecular Analysis of Secondary Vein Patterning

1. 西伯思实验室的研究目标是了解静脉形态的分子基础。植物脉包含两个特殊的组织，木质部和韧皮部，它们的功能主要是运输水和光合作用的最终产物。这些运输功能是至关重要的，因为水通常只直接供应给根，但整个植物都需要水，光合作用的固定碳端点仅在光合器官（如叶子）中产生，但所有生长组织都需要水。因此，需要适当的静脉图案来满足所有器官的需要。Sieburth实验室使用遗传方法来识别在静脉模式中起作用的基因。这些研究已经确定的两个关键基因是SCARFACE （SFC）和VARICOSE （VCS）。SFC突变体有破碎的次脉。在原形成层发育的最早阶段，可以看到破碎的静脉，这表明SFC在建立连续线性次静脉模式方面发挥了作用。相比之下，vcs突变体具有紊乱的次脉。VCS编码一个WD结构域蛋白，表明它在蛋白-蛋白相互作用中起作用。在这些突变体和其他突变体的基础上，建立了一个强调叶片发育和叶脉模式之间联系的次生叶脉模式模型。本研究项目的目标是确定VCS和SFC基因的功能。VCS的表达模式将在正常植物和暴露于生长素和极性生长素运输抑制剂的植物中进行表征；将对VCS和生长素转运组分之间的双突变体进行表征；以及其产物与VCS相互作用的基因将被识别。SFC基因将被鉴定，生长素的影响将通过生长素报告基因和SFC与生长素转运或生长素反应组分之间的双突变体来表征。2. 通过开展这项研究，西伯思实验室将为本科生、研究生和博士后研究人员提供培训。本科生通常被赋予描述突变表型和进行高分辨率绘图的项目。对于这些学生来说，这些是重要的研究工具，他们中的许多人都在考虑未来的医学职业。西伯思博士向本科生群体（包括专门的女本科生小组）发表研究演讲，并鼓励她们寻求研究机会（特别是在她的实验室）。希伯思实验室的本科生成员被敦促参加会议并展示他们的研究。西伯思实验室的三名本科生研究人员参加了全国本科生研究人员会议（UNCR）并介绍了他们的工作。

1. Intellectual MeritThe research goal of the Sieburth lab is to understand the molecular basis for vein pattern. Plant veins contain two specialized tissues, xylem and phloem, which function to transport primarily water and photosynthetic end products, respectively. These transportation functions are crucial, as water is typically only directly supplied to roots, yet is needed throughout the plant, and the fixed carbon endpoints of photosynthesis are produced only in photosynthetic organs (e.g. leaves), yet are required by all growing tissues. Thus, appropriate patterning of veins is required to supply needs for all organs.The Sieburth lab uses a genetic approach to identify genes that function in vein patterning. Two crucial genes that have been identified by these studies are SCARFACE (SFC) and VARICOSE (VCS). sfc mutants have fragmented secondary veins. Fragmented veins are visible at the earliest stages of procambium development, indicating a role for SFC in establishing the pattern of continuous linear secondary veins. In contrast, vcs mutants have disorganized secondary veins. VCS encodes a WD domain protein, indicating that it functions in protein-protein interactions. Based on these and other mutants, a model for secondary vein patterning emphasizing the links between leaf development and vein pattern has been developed. The goals for this research project are to determine the functions of the VCS and SFC genes. VCS expression patterns will be characterized for normal plants and plants exposed to auxin and polar auxin transport inhibitors; double mutants between vcs and mutants for auxin transport components will be characterized; and genes whose products interact with VCS will be identified. The SFC gene will be identified, and the influence of auxin will be characterized both using auxin reporter genes and by characterizing double mutants between sfc and mutant for auxin transport or auxin response components. 2. Broader Impacts By carrying out this research, the Sieburth lab will provide training to undergraduate, graduate, and postdoctoral investigators. Undergraduates are typically given projects to characterize the phenotype of a mutant and to carry out high-resolution mapping. These are important research tools for these students, many of whom contemplate a future career in medicine. Dr. Sieburth presents research talks to undergraduate groups, including specialized small groups of undergraduate women, and encourages them to seek research opportunities (especially in her lab). Undergraduate members of the Sieburth Lab are urged to attend and present their research at meetings. Three undergraduate researchers in the Sieburth Lab attended and presented their work at the National Conference for Undergraduate Researchers (UNCR).