title: Characterization of GhRac1 GTPase expressed in developing cotton (Gossypium hirsutum L.) fibers.
abstract: Cytoskeleton assembly plays an important role in determining cotton fiber cell length and morphology and is developmentally regulated. As in other plant cells, it is not clear how cytoskeletal assembly in fibers is regulated. Recently, several Rac/Rop GTPases in Arabidopsis were shown to regulate isotropic and polar cell growth of root hairs and pollen tubes by controlling assembly of the cytoskeleton. GhRac1, isolated from cottonseeds, is a member of the Rac/Rop GTPase family and is abundantly expressed in rapidly growing cotton tissues. GhRac1 shows the greatest sequence similarity to the group IV subfamily of Arabidopsis Rac/Rop genes. Overexpression of GhRac1 in E. coli led to the production of a functional GTPase as shown by in vitro enzyme activity assay. In contrast to other Rac/Rop GTPases found in cotton fiber, GhRac1 is highly expressed during the elongation stage of fiber development with expression decreasing dramatically when the rate of fiber elongation declines. The association of highest GhRac1 expression during stages of maximal cotton fiber elongation suggests that GhRac1 GTPase may be a potential regulator of fiber elongation by controlling cytoskeletal assembly.
authors.affiliation: USDA-ARS, Southern Regional Research Center, New Orleans, LA 70124, USA.
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Triplett
mesh_terms: D000595:Amino Acid Sequence; D015139:Blotting, Southern; D002473:Cell Wall / Q000235:genetics; D032561:Cotton Fiber; D003599:Cytoskeleton / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D003368:Gossypium / Q000235:genetics / Q000254:growth & development*; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000235:genetics* / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; C116764:RAC13 protein, Gossypium hirsutum; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein