Expression datasets relating to the Arabidopsis female gametophyte have enabled the creation of a tool set which allows simultaneous visual tracking of each specific cell type (egg, synergids, central cell, and antipodals). This cell-specific, fluorescent labeling tool-set functions from gametophyte cellularization through fertilization and early embryo development. Using this system, cell fates were tracked within Arabidopsis ovules following molecular manipulations, such as the ablation of the egg and/or synergids. Upon egg cell ablation, it was observed that a synergid can switch its developmental fate to become egg/embryo-like upon loss of the native egg. Also, manipulated was the fate of the somatic ovular cells, which can become egg- and embryo-like, reminiscent of adventitious embryony. These advances represent initial steps toward engineering synthetic apomixis resulting in seed derived wholly from the maternal plant. The end goal of applied apomixis research, fixing important agronomic traits such as hybrid vigor, would be a key benefit to agricultural productivity.

Center for Plant Cell Biology (A.E.A., M.S., E.J.S., T.G., A.R., H.J., G.R.H., N.V.R.), Department of Botany and Plant Sciences (A.E.A., M.S., E.J.S., T.G., A.R., G.R.H., N.V.R.), Institute for Integrative Genome Biology (T.G., H.J., G.R.H., N.V.R.), and Department of Plant Pathology and Microbiology (H.J.), University of California, Riverside, California 92521; Department of Biology, University of Minnesota, Duluth, Minnesota 55812 (B.W.K., C.C.); Genetics Graduate Group and Department of Plant Sciences, University of California, Davis, California 95616 (A.M.W., D.J.K.); and School of Life Sciences and Biotechnology, Korea University, Seoul 136–701, Korea (H.C.J., O.K.P.)

We identified an Arabidopsis (Arabidopsis thaliana) ethyl methanesulfonate mutant, modified vacuole phenotype1-1 (mvp1-1), in a fluorescent confocal microscopy screen for plants with mislocalization of a green fluorescent protein-delta tonoplast intrinsic protein fusion. The mvp1-1 mutant displayed static perinuclear aggregates of the reporter protein. mvp1 mutants also exhibited a number of vacuole-related phenotypes, as demonstrated by defects in growth, utilization of stored carbon, gravitropic response, salt sensitivity, and specific susceptibility to the fungal necrotroph Alternaria brassicicola. Similarly, crosses with other endomembrane marker fusions identified mislocalization to aggregate structures, indicating a general defect in protein trafficking. Map-based cloning showed that the mvp1-1 mutation altered a gene encoding a putative myrosinase-associated protein, and glutathione S-transferase pull-down assays demonstrated that MVP1 interacted specifically with the Arabidopsis myrosinase protein, THIOGLUCOSIDE GLUCOHYDROLASE2 (TGG2), but not TGG1. Moreover, the mvp1-1 mutant showed increased nitrile production during glucosinolate hydrolysis, suggesting that MVP1 may play a role in modulation of myrosinase activity. We propose that MVP1 is a myrosinase-associated protein that functions, in part, to correctly localize the myrosinase TGG2 and prevent inappropriate glucosinolate hydrolysis that could generate cytotoxic molecules.

The small plant Arabidopsis thaliana has been an indispensable tool for plant biologists working in fields that utilize cell biology, molecular biology, and genetics; these topics are almost universal in plant biology studies, ranging from genomics to ecology. In this chapter, we present a start-to-finish approach to high-throughput imaging of Arabidopsis that caters to two different audiences: those who are working with plants for the first time, and plant scientists looking to the apply high-throughput imaging to existing projects.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

We have focused our studies in the past several years on understanding protein trafficking from the secretory system to the vacuole—an organelle present in all plant cells. Here, we report an approach for generating and screening plants with defects in vacuolar biogenesis. Plant vacuoles are