Poster: Reproductive development

Abs # 370: Expression Based Gene Discovery of Putative Regulators of Ovule Development in Arabidopsis

Presenter:	Skinner, Debra J., djskinner@ucdavis.edu
Authors	Skinner, Debra J. (A)   Gasser, Charles S. (A)
Affiliations:	(A): Molecular and Cellular Biology, UC Davis, Davis, CA

Arabidopsis ovules comprise four morphologically distinct parts: the nucellus, which contains the embryo sac, two integuments that become the seed coat and the funiculus, that anchors the ovule within the carpel. Analysis of mutants has shown that ovule morphogenesis relies on tightly regulated genetic interactions and can be used as a model to study developmental processes. Redundancy or pleiotropic effects may preclude observation of some mutants in screens for phenotypic changes. In order to access such genes, Affymetrix microarrays are being used for expression-based gene discovery. These experiments are designed to identify sets of genes expressed in particular ovule parts by comparison of pistil mRNA from wild type with mRNA from mutants that lack these parts. Two mutants with ovule phenotypes have been investigated: inner no outer (ino), which lacks the outer integument, and aintegumenta (ant), which lacks both integuments. Two pools of pistils representing early and late stages of ovule development were used. From the 22,810 genes represented on the chip there are approximately 250 genes that show variation among the wild-type and mutant genotypes and stages (coefficient of variation >0.4). Cluster analysis and pairwise comparisons of this set of genes have been used to reveal several classes of expression profile during ovule development. For example, a small set of genes is present in wild type and ino pistils but absent from ant pistils, indicating that these genes may be preferentially expressed in the inner integument. Mutations in one member of this set, a putative transcription factor, results in altered integument morphology. Expression verification as well as loss-of-function analyses will be described for selected genes discovered in these experiments.