This paper by Nathalie Leonhardt, June Kwak, et al., as published in the journal Plant Cell in March, 2004, reports on microarray expression data in specific cell types: guard cells and, independently, mesophyll cells. The guard cell system has been developed into a well-suited system for plant signal transduction network studies and the knowledge of which genes are expressed in a certain cell type allows an addressing of the redundancy problem in signal transduction studies. Furthermore, we report microarray expression data in both cell types in the presence of the plant stress hormone abscisic acid, which regulates mRNA levels of many genes.

Methods for isolating >98% pure guard cells are described. These can be used in future microarray studies of guard cells under diverse conditions or in unique mutant backgrounds. The raw microarray data published in this paper are publicly available at our lab's web site and at TAIR. Furthermore we characterize a mutant phenotype of a protein phosphatase (PP2C) that is highly expressed in guard cells and regulated by the hormone abscisic acid. This PP2C mutant shows hypersensitivity to abscisic acid.

This paper reports expression of genes on a genomic scale in an important plant cell type, guard cells, that regulate gas exchange and water loss in plants.

This work is an essential stepping stone in our long-term research goals. The reported methods were developed and improved in our lab over several years, to address the redundancy problem in plant signaling networks. The developed methods were then used to obtain genomic scale expression in mesophyll cells and guard cells. The latter have taught us much about plant ion channel functions and plant signal transduction branches, with many interesting new questions becoming addressable.