Arabidopsis Me-0 vs tetraploid Col

To investigate gene expression differences related to the regulation of stomatal aperture between two Arabidopsis accessions, Me-0 and tetraploid Col, we performed microarray analysis on guard cell protoplasts from these two accessions. We identified 1,777 probes as up-regulated and 1,706 probes as down-regulated differentially expressed genes (DEGs) in Me-0 compared with tetraploid Col (adjusted P-value < 0.001 and log 2 fold change of greater than 1 or less than -1). Using gene set analysis to functionally characterize DEGs, there were eight significant gene sets (at the level of P-value < 0.01) among the up-regulated genes and seven significant gene set among the down-regulated genes. Genes with the lowest P-value among the up-regulated genes were related to “plant-type cell wall loosening”, an essential step in guard cell swelling. Most of the down-regulated genes were related to the defense responses for immunity, hypoxia, and ozone, which also influence stomatal responses or gas exchange. We propose that these gene expression differences may cause the difference in stomatal aperture between Me-0 and tetraploid Col. Four samples from Me-0 and three samples from tetraploid Col are used for a microarray analysis.