Poster: Regulation of gene expression

Abs # 748: Integrated Genomic and Metabolic Analyses of Hypoxic Stress Response in Flooding-Tolerant P_SAG12:ipt Arabidopsis

Presenter:	Liu, Fenglong , fliu@tigr.org
Authors	Liu, Fenglong  (A)   VanToai, Tara  (B)   Klapa, Maria  (C)   Moy, Linda  (A)   Bock, Geoffrey  (A)   Kanani, Harin  (C)   Linford, Lara  (A)   Quackenbush, John  (A) (C)
Affiliations:	(A): The Institute for Genomic Research (B): USDA-ARS-Soil Drainage Research Unit (C): Department of Chemical Engineering, University of Maryland

Plants have evolved adaptation mechanisms to sense oxygen limitation in their environment and make coordinated physiological and structural adjustments to enhance their hypoxic tolerance. To gain insight into how plants respond to conditions of low oxygen, we examined both gene transcript and cellular metabolite levels at 9 time points over 24 hours, in wild-type and flooding-tolerant transgenic Arabidopsis plants with auto-regulated cytokinin synthesis under normaxic or hypoxic conditions. Gene expression data were collected using whole-genome DNA amplicon microarrays representing over 27,000 predicted nuclear, chloroplastic, and mitochondrial genes; profiles of metabolites were obtained using GC-MS. Analysis of expression data revealed statistically significant temporal patterns of gene expression. Analysis based on Gene Ontology (GO) terms indicated a significant down-regulation of genes associated with membranes and nucleosome structures during the early and late responses to hypoxia. Genes involved in glycolysis and fermentation pathways (SS, FK, ALD, PK, PDC, ADH1, LDH1, AAT), ethylene synthesis and perception (ACC oxidase, ACS, ETR2), calcium signaling (CAMs), nitrogen utilization (ANR1, NR1, ASP2), trehalose metabolism (TPP, TRE), and translational machinery (EF1-alpha) were up-regulated under conditions of low oxygen. Genes encoding water channels and ion transporters were down regulated in response to hypoxia. Promoter analysis revealed an over-representation of AtMYB2 transcription factor binding motif (GT-motif) and novel cis-elements present in the promoter regions of the up-regulated genes. Correlation of gene expression and metabolite profile data enables inferences into enzyme activities and dynamic metabolite fluxes along hypoxia-perturbed pathways.