棉 花 学 报 Cotton Science 2007，19(6)：419-423
Study on Transient Expression of Target Gene in the Epidermal Cells of Cotton Ovules via Particle Bombardment Abstract：Cotton fibers are unicellular trichomes which differentiate from epidermal cells of developing cotton ovules. They have been considered as an ideal model for studying plant cell elongation and cell wall biogenesis. A large number of regulatory genes are involved in the process of fiber differentiation and development. Only a few is known how they control and regulate the entire process of fiber development. Because generating transgenic cotton needs a long period of time and transformation efficiency of cotton is still low，it is necessary to develop a fast and efficient transient expression assay system for characterization of cotton fiber-specific expression genes and promoters as well as test of their function. Cotton ovule culture (0-1 DPA) and β -glucuronidase gene (GUS) were used in biolistic transformation experiment. The transient expression vector contains two expression cassettes. GUS reporter gene is driven by CaMV35S promoter，the target gene is under control of cotton fiber-specific promoter RDL1. Because GUS reporter gene and target gene simultaneously express in single fiber cell，the transient expression assay system could provide an effective method to investigate the relationship between the expression of target gene and the development process of fiber in transformed single cotton fiber cell. The conditions for bombardment were optimized to enhance the transformation efficiency. The result showed that the highest transformation efficiency of GUS was obstained when one day postanthesis (DPA) ovules were applied. The optimal condition for bombardment include helium pressures of 1100 psi，distance of 9 cm and bomb times of twice.
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