To develop custom cDNA microarray for specific crops: The spotted cDNA microarrays are useful for those non-model systems, because they do not require previous knowledge of genomic sequences. While genome expression analysis may still be difficult using this technology, due to some limitations with the source clones and in fabrication, it provides a quick way to analyze gene expression at the transcription level in parallel. In addition, for species with a high polymorphism frequency in their genome, such as in maize, the larger probes used in the spotted DNA microarray are superior to the oligonucleotide probes used in GeneChip microarray when comparing expression data among different varieties. A system with high-throughput potential was established for custom cDNA microarrays in our facility. This system includes Tecan robotic liquid handling systems for probe normalization and re-arraying; a GeneMachine OmniGrid arrayer with plate hotels and a server arm for high-speed printing; a GenomicSolution GeneTAC an automatic hybridization station for consistent hybridization and washing; a Packard ScanArray5000 with automatic slide loader for slide scanning; and BioDiscovery's ImaGene software for image-processing with batch mode capacity. With this system, a set of high-density maize genome arrays was developed and used for various projects. The set consists of two arrays; each with 20,000 elements represented 10,000 genes. The performance of these arrays is summarized in Table 2.