Expression profile of maize microRNAs corresponding to their target genes under drought stress

Microarray assay of four inbred lines was used to identify 303 microRNAs differentially expressed under drought stress. The microRNAs were used for bioinformatics prediction of their target genes. The majority of the differentially expressed microRNA families showed different expression profiles at different time points of the stress process among the four inbred lines. Digital gene expression profiling revealed 54 genes targeted by 128 of the microRNAs differentially expressed under the same stress conditions. The differential expression of miR159 and miR168 was further validated by locked nucleic acid northern hybridization. These results indicated that miR159 and miR168, as well as numerous other microRNAs, play critical roles in signaling pathways of maize response to drought stress. However, the level of the post-transcriptional regulation mediated by microRNAs had different responses among genotypes, and the gene expression related to signaling pathways under drought stress is also regulated, possibly by multiple mechanisms.