Cotton provides about 55% of the fibre in textile manufacturing globalIy and is an important contributor to the Australian economy. The cotton fibre is a single cell hair (trichome) growing out from the surface of the cotton seed epidermis. Little is known about the molecular basis for the control of which cells initiate fibre growth and how that growth is regulated to produce fibres of a desired quality. We have initiated a project to study the genes expressed during the early stages of fibre cell initiation in cotton using both directed approaches to target genes that might be expected to have a role in fibre initiation, as well as a genomics approach to look for novel genes expressed in the early stages of fibre growth. cDNA libraries from early stage cotton ovules have been produced and we have started sequencing clones at random from these libraries (supplemented by a one year grant from CRDC - CSPllOC) and we will use bioinformatics techniques(computer database searching) to try to identify clones that might have a role in the control of fibre development processes (particularly genes known to control other genes - transcription factor genes). This can generate thousands of candidates and the next stage of the process is to narrow these genes down to aworkable number based on their patterns of expression in plants. To do this we can use micro-arrays - these are glass slides onto which small amounts of each of many thousands of the genes are spotted in an ordered sequence. By then using fluorescently labelled probes of the total RNA from particular stages or conditions we can use a dedicated scanner and computer software to measure the level of expression of all 10,000 or more genes under different conditions, such as at different stages of fibre initiation and development or between cultivars with different quality attributes. Genes whose expression goes up, down or stays the same can be identified and by doing different comparisons we can hope to identify those genes controlling the initiation process or quality traits.