DNA Microarrays

DNA microarrays can be set up robotically by depositing specific fragments of DNA at indexed locations on microscope slides. With  current technology, cDNAs, EST clones or open reading frames (ORFs) from sequenced genomes can be set up in microarrays of 10 000 spots
per 3.24 cm2, thus the whole genome of Arabidopsis could be displayed on one microscope slide. Fluorescently labelled mRNA probes are hybridised on to the array and specific hybridising sequences are identified by their fluorescent signals. Microarray technology can be used to study gene expression patterns, expression fingerprints, DNA polymorphisms and, in theory, as a breeding tool to evaluate new genetic materials, for a specific trait (e.g. drought tolerance), together with phenotypic tests.