Genome-wide transcriptome analysis of two maize inbred lines under drought stress.

Drought stress greatly affects plant growth and crop yield. To understand the transcriptome dynamics during drought stress in maize seedlings, genome-wide gene expression profiling was compared between the drought-tolerant line Han21 and drought-sensitive line Ye478 using Affymetrix Maize Genome Array containing 17,555 probe sets. The results showed that in response to drought, the Han21 line had fewer probe sets with significant expression change than the Ye478 line and both lines had a common set of ~2,600 regulated probe sets under drought stress. The potential components of the abscisic acid signaling pathway were significantly identified from the common probe sets. A total of 827 probe sets with significantly differential expression between the two lines under drought stress were identified. The differential expression levels of cell wall-related and transporter genes may contribute to the different tolerances of the two lines. Additionally, we found that, compared to the sensitive line Ye478, the transcriptional levels of drought-responsive probe sets in the tolerant line Han21 recovered more quickly after re-watering, and more probe sets in the tolerant line Han21 were exclusively up-regulated at the re-watering stage. Our study provides a global gene expression dynamics of two maize inbred lines during drought stress and re-watering and will be valuable for further study of the molecular mechanisms of drought tolerance in maize.