Microarray analysis of gene expression of the Arabidopsis leaf and callus

Callus formation is usually a necessary step in regenerating a new plant from detached plant tissues, and the nature of the callus is similar to that of the root meristem. In this study, we intended to address the molecular basis that directs different plant tissues to form the root-meristem-like callus. We found that leaves, but not roots, of the Polycomb group (PcG) double mutant curly leaf-50 swinger-1 lost the ability to form a callus. Using ChIP-chip analysis, we identified genes that are changed markedly in the histone H3 lysine 27 trimethylation (H3K27me3) levels during callus formation from leaf explants. Among these genes, a number of leaf-regulatory genes were repressed through PcG-mediated H3K27me3. Conversely, certain auxin pathway genes and many root-regulatory genes were derepressed through H3K27 demethylation. Our data indicate that genome-wide H3K27me3 reprogramming, through the PcG-mediated H3K27me3 and the H3K27 demethylation pathways, is critical in directing cell fate transition.

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He C, Chen X, Huang H, Xu L