Expression Vector Construction And Functional Analysis Of Cotton Rac Protein Gene (GhRacB)

Cotton (Gossypium hirsutum L.) is an economically important crop throughout the world and provides an important source of natural fiber to textile industry. Cotton seed is also an important source of feed protein and edible oil. The cotton fiber is a single-celled fiber differentiated from epidermal cells of ovules. The development of cotton fiber can be divided into four stages: initiation, elongation (primary cell wall synthesis), secondary cell wall synthesis and maturation. The cell wall components of cotton fiber are synthesized and transported by a functionally-integrated membrane system of endoplasmic reticulum, Golgi complex, and plasmalemma. Given that the rapid elongation and extraordinary final length, the cotton fiber has also been an excellent model for the study of polar cell growth.Rac proteins are small GTPase, belong to Rho GTPase family. As a signal switch on menbranes, Rac GTPase regulates many physiological processes during plant development, including polar cell growth, second cell wall synthesis, disease resistance and hormone signal transduction.In order to study the functions of Rac GTPase and its role in cotton fiber development, a Rac protein gene (GhRacB) were previously cloned from cotton fiber. It was demonstrated that GhRacB was expressed preferentially in elongating fibers, suggesting that GhRacB may play an important role in the early stage of fiber development.To further analyze the functions of GhRacB gene in the development of cotton, we constructed overexpression and antisense suppression vectors of GhRacB, which were then transferred into cotton by Agrobacterium-mediated method. The resultant transformants were finally compared phenotypiclly. The main results are as followings.1) The overexpression and antisense suppression vectors were successfully constructed by inserting the GhRacB gene to the expression vector P5, in sense and antisense orentiation,...