Overexpression of the Gossypium barbadense Actin-Depolymerizing Factor 1 Gene Mediates Biological Changes in Transgenic Tobacco

The function of a member of the actin-depolymerizing factor family from Gossypium barbadense, GbADF1, was investigated. Tobacco (Nicotiana tabacum) lines expressing GbADF1 were produced by Agrobacterium-mediated transformation. Southern and northern blot analyses showed that GbADF1 was successfully incorporated as a single copy into the tobacco genome and stably expressed in three lines of T₁ transgenic tobacco plants. Biological changes were detected in these transgenic lines, wherein GbADF1 transgenic seedlings exhibited shorter hypocotyls along with fewer root hairs than those of control plants. Moreover, guard cells of leaves of the transgenic plants were induced to close stomata, while flowering was delayed 5 days in T₁ lines compared to those of empty vector transgenic control plants. Segregation of GbADF1 in the T₂ generation fits the expected 3:1 ratio corresponding to a single dominant gene. Subsequently, GbADF1 was fused to the green fluorescent protein gene to generate a fusion expression vector. Transient expression analysis indicated that this fusion protein was localized in the nucleus and cytoskeleton of epidermal cells of onion. These results suggest that actin-depolymerizing factor 1 gene from G. barbadense plays an important role in the process of plant cell morphogenesis.