Genes expression analyses of sea-island cotton (Gossypium barbadense L.) during fiber development.

Sea-island cotton (Gossypium barbadense L.) is one of the most valuable cotton species due to its silkiness, luster, long staples, and high strength, but its fiber development mechanism has not been surveyed comprehensively. We constructed a normalized fiber cDNA library (from -2 to 25 dpa) of G. barbadense cv. Pima 3-79 (the genetic standard line) by saturation hybridization with genomic DNA. We screened Pima 3-79 fiber RNA from five developmental stages using a cDNA array including 9,126 plasmids randomly selected from the library, and we selected and sequenced 929 clones that had different signal intensities between any two stages. The 887 high-quality expressed sequence tags obtained were assembled into 645 consensus sequences (582 singletons and 63 contigs), of which 455 were assigned to functional categories using gene ontology. Almost 50% of binned genes belonged to metabolism functional categories. Based on subarray analysis of the 887 high-quality expressed sequence tags with 0-, 5-, 10-, 15-, and 20-dpa RNA of Pima 3-79 fibers and a mixture of RNA of nonfiber tissues, seven types of expression profiles were elucidated. Furthermore our results showed that phytohormones may play an important role in the fiber development.

Function analysis of promoter trapping system after inserted into cotton (Gossypium hirsutum L. ) genome.

The technique of promoter trapping was developed to investigate its viability in cotton ( Gossypium hirsutum L.) functional genomics. 141 independent transformants of cotton were generated via Agrobacterium tumefaciens mediated transformation, of which 97% showed positive by PCR detection. The reporter, GUS gene, was expressed to different extent in different organs, with a frequency of 48% in roots, 9.2% in vascular bundles of stem, 5.2% in leaves, and 51% in flowers. Meanwhile, we discovered that there existed great differences in expression patterns among different transgenic lines. Their GUS expression patterns were organ- or tissue-specific or ubiquitous in all of the plants. The promoter trapping system developed here was characterized as an effective method for creating mutants with diverse reporter gene expression patterns, which laid a solid foundation for further research of functional genomics in cotton.