Functional analysis of nodulin-like promoter in transgenic cotton plants

For the first time, a nodulin-like gene promoter was isolated from Gossypium hirsutum L. Guo Y18 by means of inverse PCR. Three plant expression vectors were constructed for functional identification of the promoter. These vectors were different only in promoter regions; three truncations of the nodulin-like promoter took the place of the CaMV35S promoter in the pBI121 plant expression vector. Then, the three vectors were introduced into cotton plants via the pollen tube pathway. The expression patterns of the gus gene driven by nodulin-like promoter truncations were investigated in the offspring of transgenic cotton plants. Histochemical GUS staining and fluorescence quantitative analysis were performed to achieve this goal. The results showed that the nodulin-like promoter was a strong, highly reproductive organ-specific promoter, which demonstrated a much higher driver activity than the CaMV35S promoter did in cotton reproductive organs, but relatively lower activity in vegetation. Identification of the speciality and strength-determining regions of the nodulin-like promoter was also undertaken.