CAREER: Genetics of Pattern Formation in the Arabidopsis Shoot Apex

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The shoot apical meristem (SAM) is the ultimate source of all above groundtissues of the plant. The SAM gives rise to leaves, stems, flowers, andaxillary buds, and is responsible for the pattern of the shoot. Despitethe crucial role of the shoot apical meristem in plant development, almostnothing is known about the mechanisms by which organs are produced from theflanks of this structure. Using a novel mutagenesis system, enhancer trap(ET) and gene trap (GT) transposant lines that exhibit GUS reporter geneexpression in discrete domains in the SAM or surrounding cells have beenidentified. Two transposant lines show GUS expression specific to the SAM. The genes controlling GUS expression in these lines could play a role inSAM identity and/or function. Eight transposant lines have been identifiedthat show GUS expression in discrete, novel domains surrounding the SAM.These expression patterns do not appear to reflect anatomical ormorphological features, but define new domains based on gene expression.The genes controlling GUS expression in these lines may function to defineboundaries during organ initiation. These lines were identified based onGUS expression patterns, and the genes controlling that expression are ofunknown function. A series of analyses will be performed in order to beginto understand the role that these genes play in meristem function andorganogenesis. The genes will be cloned and sequenced, and a detailedcharacterization of their expression patterns will be performed. In orderto identify genetic relationships between genes that function in themeristem, GUS expression in our gene trap and enhancer trap lines will beexamined in backgrounds containing mutations that affect meristem function,and in transgenic plants that ectopically express selected meristem genes. The educational component of this proposal is geared towards trainingundergraduate and graduate students and postdoctoral researchers in modernmethods in Arabidopsis research. Arabidopsis thaliana is a model organismfor studies in plant biology. The many available Arabidopsis resources areof use to all plant biology researchers. In order for plant biologyresearchers to be able to take full advantage of the Arabidopsis resourcesthat are available, it is important that they be familiar with the standardmethods used in Arabidopsis research. To this end, an intensive laboratorycourse will be developed, that will teach standard Arabidopsis methods.Materials from the PI's research program will be used for the laboratories. In addition, the PI will serve as a mentor to graduate students andpostdoctoral researchers who will carry out the research component of thisproposal.