| Summary: | Global gene expression in Sorghum bicolor, an important crop showing drought
tolerance in arid and semi-arid cultivated areas, was monitored to exposure of 8-days
seedlings to water deficit (20% polyethylene glycol) or cold stress (4 úC). A sorghum
cDNA microarray, including ~13,000 (milestone version 1) or ~28,000 (milestone
version 2) unigenes, was used to examine gene expression in shoots and roots at 3 and
27hours after stress treatment. ~1,300 and ~2,300 genes were modulated by water deficit
and cold stress, respectively. Up-regulated genes included previously identified stressinduced
genes such as early drought-induced gene, dehydrin, late embryogenesis
abundant gene, glycin and proline-rich gene, and water stress-inducible genes as well as
unknown genes. Genes involved in signal transduction, lipid metabolism, transporter,
and carbohydrate metabolism are induced. Quantitative real-time PCR was used to
quantify changes in relative mRNA abundance for 333 and 108 genes in response to
water deficit and cold stress, respectively. Stress-induced genes were classified by
kinetics. Eighteen of 108 cold-induced genes were modulated by cold but not by ABA and PEG treatment. This research provides the starting point for detailed analysis and
comparison of water deficit and cold modulated gene networks in sorghum.
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