Cell wall remodeling in Arabidopsis stamen abscission zones Temporal aspects of control inferred from transcriptional profiling

Organ shedding requires cell separation within abscission zones (AZs). Functional genomic AZ studies have been limited by their small size and low incidence. Optimization of laser capture microdissection (LCM) for AZs and other specialized cell types in Arabidopsis1 allowed recent characterization of the floral stamen AZ transcriptome responding to a developmental shedding cue. 2 Analyses focused on 551 AZ transcripts (AZ(551)) that were regulated at the highest statistical significance (p <= 0.0001) over five stages of stamen development spanning pre-pollination to organ shed. 2 Here, we seek a fuller understanding of AZ integrity control by relaxing P value restrictions on statistical significance ten-fold to generate an expanded population of 1461 stamen transcripts (AZ(1461)). Cell wall remodeling functions in AZ(1461) are significantly over-represented relative to all transcripts represented on the whole genome GeneChip. Hierarchical clustering of gene expression data corresponding to cell wall-related transcripts suggests a temporal model for AZ remodeling in Arabidopsis stamens destined to abscise.