Cotton is the leading fiber crop in the world. For studying the major fiber development specific genes, cDNA libraries were used to establish 1000 ESTs (expressed sequence tags) each from the fast growing fibers of Calotropis procera and Gossypium hirsutum L. Four orthologs of expansins (CpEXPA1, CpEXPA2, CpEXPA3 and CpEXPA4) and four of aquaporins (CpTiP1, CpTiP2, CpPiP1 and CpPiP2) were found to be the most abundantly expressed transcripts in C. procera fiber cells. Cotton fiber ESTs showed two orthologs of expansin, one for aquaporin (GhPiP1) and one transcript for sucrose synthase. The GhPiP1 had 70% amino acid identity to CpPiP1, while no homologue for CpPiP2 was detected in cotton fibers. Real-time PCR data showed that CpPiP2 and CpEXPA3 displayed high abundace of transcripts in C. procera hollow fibers that elongate to more than 45mm. Sucrose synthase transcript was found at its peak in 5-15DPA. The CpPiP2 expression cassette controlled by CaMV 35S promoter was transformed into Nicotiana tabacum, which resulted in highly dense and elongated leaf and stem trichomes. In order to test the individual genes in cotton cv. FH942, the CpEXPA3, CpPiP2 and Susy4 were cloned in pSB219 vector and transformed through Agrobacterium mediated transformation of mechanically incised embryo apices. The ammonium gluphosinate, phosphinothricin selected putative transgenics showed the PCR amplifications uniformly until the six leaf stage. However, at later stages of plant development variability in transgene detection was observed from leaf to leaf, T1 plants showed no respective amplifications. In order to explore the reason for this inconsistency, transformed GUS and GFP expression cassettes showed localized patches for the marker genes. The ChvA and HrCA genes of Agrobacterium genome could not be detected by at any of the plant development stage which excluded the migration of Agrobacterium within the plant tissues. It was inferred that integration of the transgene might have occurred in the somatic cell layers L1 and/or L2 of the embryo apex but not in L3 (germline) cells. It was concluded that direct transformation through apex transformation was not possible as the germline transformants could not be obtained from two thousand and five hundred embryos.