Increasing stems length and leaf area in transgenic tobacco plants expressing Arabidopsis AtEXPA18 gene

Expansins are cell wall proteins that due to changes in pH، causing the expansion of the cell wall. These proteins are causing deformation of walls through loosening hydrogen bonds between the cellulose and polymer matrix microfibrils. In this study، a root specific gene called AtEXPA18 -that directly affect the formation of root hairs and also its role have been proved in other parts of the plant- was isolated from Arabidopsis thaliana and cloned into the plant expression vector PBI121 under the control of CaMV 35S promoter and NOS terminator and finally was transferred to Agrobacterium. This gene was then transferred to the tobacco through leaf disks transformation. Plants obtained from regeneration was selected on selective medium containing kanamycin. Plants were transferred to the greenhouse and after growth، molecular and morphological analysis was conducted. To prove the transformation of plants in genome wide، DNA was extracted and AtEXPA18 gene was amplified by polymerase chain reaction technique with specific primers. Also، the results of RT-PCR confirmed the transcription of transgene in transgenic tobacco، after RNA extraction and cDNA synthesis. The obtained transgenic tobacco plants were shown to have significantly larger leaves and longer stems compared to control plants. The results obtained with other results demonstrate the role of mentioned gene in cell expansion and recommend it as a public growth regulator to obtain transgenic plants with larger organs.