Genetic and Molecular Analysis of Secondary Vein Patterning

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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).