Cotton fiber biology: Integrating genomics and development for improving fiber traits

Understanding the underlying genetic mechanisms that control fiber growth and development and govern complex fiber traits is key to implementing long term strategies to improve yield and fiber quality using molecular approaches. As part of our fiber genomics initiative, a gene discovery project generated almost 50,000 ESTs (expressed sequence tags) from rapidly elongating cotton fibers that currently define the cotton fiber transcriptome, which represents ~35% of the cotton genome. The genetic complexity of elongating cotton fibers is very high and reflects the highly exaggerated growth of rapidly elongating fibers, indicating a very metabolically active cell type. Expression profiling of cotton long oligonucleotide arrays representing the fiber transcriptome provides a global view of the thousands of expansion-associated genes that are differentially regulated during fiber development, and provide candidate genes for genetic modification. With a genomic toolbox, candidate genes and a developmental model in hand, we can begin to focus determining fiber gene function using reverse genetic approaches as a step towards genetic modification of the fiber transcriptome. New innovations in cotton transformation and regeneration technology have improved and simplified the introduction of transgenes into cotton, and major strides have been made towards genotype-independent transformation. We are now entering a new era of cotton research in the areas of functional genomics and applied biotechnology with a promising future for manipulating the fiber transcriptome for improvement of fiber traits.