The phytohormone abscisic acid (ABA) enables plants to adapt to adverse environmental
conditions through the modulation of metabolic pathways and of growth and developmental programs.
We used comparative microarray analysis to identify genes exhibiting ABA-dependent expression
and other hormone-dependent expression among them in Oryza sativa shoot and root. We
identified 854 genes as significantly up- or down-regulated in root or shoot under ABA treatment
condition. Most of these genes had similar expression profiles in root and shoot under ABA treatment
condition, whereas 86 genes displayed opposite expression responses in root and shoot. To examine
the crosstalk between ABA and other hormones, we compared the expression profiles of the ABAdependently
regulated genes under several different hormone treatment conditions. Interestingly,
around half of the ABA-dependently expressed genes were also regulated by jasmonic acid based on
microarray data analysis. We searched the promoter regions of these genes for cis-elements that could
be responsible for their responsiveness to both hormones, and found that ABRE and MYC2 elements,
among others, were common to the promoters of genes that were regulated by both ABA and JA.
These results show that ABA and JA might have common gene expression regulation system and
might explain why the JA could function for both abiotic and biotic stress tolerance.
Keywords: Plant stress, ABA signaling, ABA responsive genes, JA responsive genes, Hormone crosstalk, Microarray analysis.
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