Targeted Transgene Expression in Rice Using a Callus Strong Promoter for Selectable Marker Gene Control

Area of Science:

• Plant molecular biology
• Genetics
• Biotechnology

Background:

• Precise transgene expression is crucial for plant genetic engineering and understanding gene function.
• Constitutive promoters, like Cauliflower mosaic virus (CaMV) 35S, used for selectable markers can interfere with desired transgene expression.
• Developing methods to avoid inappropriate gene regulation is essential.

Purpose of the Study:

• To characterize a novel callus strong promoter (CSP1) in rice.
• To evaluate CSP1's application for accurate transgene expression and mitigate misexpression issues.
• To establish a reliable method for acquiring transgenic rice plants with specific transgene expression for broad applications.

Main Methods:

• Characterization of the rice callus strong promoter (CSP1).
• Evaluation of CSP1-mediated hygromycin selection efficiency compared to CaMV 35S.
• Analysis of β-glucuronidase reporter gene expression driven by specific promoters in CSP1-selected transgenic rice.
• Investigation of root cellular responses to cytokinin and auxin in CSP1-selected marker lines.

Main Results:

• CSP1 exhibits high expression in callus, enabling efficient hygromycin selection comparable to CaMV 35S.
• CSP1 shows low expression in other rice tissues, minimizing potential transgene misexpression.
• Distinct β-glucuronidase expression was consistently observed in most transgenic lines selected via CSP1.
• CSP1-mediated selection facilitated the study of root responses to plant hormones, revealing differential regulation of cytokinin effects.

Conclusions:

• Callus-specific promoter-dependent selection using CSP1 effectively mitigates transgene misexpression in rice.
• CSP1 enables efficient transformation and acquisition of rice plants with reliable, specific transgene expression.
• This approach broadens the applicability of genetic engineering in rice for diverse research and agricultural purposes.