Abstract:

To investigate the expression characteristics of the target gene in transgenic cry2A* insect resistant early japonica rice, the study employed the T9 generation of transgenic cry2A* early japonica rice line ‘Songjing 9 (cry2A*)’ as experimental material. The transcription levels of the cry2A* gene in various organs at the tillering and heading stages were detected by quantitative real-time PCR (qPCR), and the expression levels of Bt protein in various organs at the tillering, heading and filling stages as well as in brown rice at the full ripening stage were determined by enzyme-linked immunosorbent assay (ELISA).The results showed that the transcription levels of the cry2A* gene varied among the same tissues of different transformation events and among different tissues of the same transformation event. The transcription levels at the heading stage were higher than those at the tillering stage, and the tissue-specific expression pattern was in the order of leaves > young panicles > culm-sheaths. In terms of temporal expression, the Bt protein levels showed the pattern of filling stage > heading stage > tillering stage in leaves and culm-sheaths, and heading stage > filling stage in young panicles; the Bt protein concentration in brown rice was the lowest at the full ripening stage. In terms of spatial expression, the pattern was leaves> culm-sheaths at the tillering stage, leaves>young panicles>culm-sheaths at the heading stage, and leaves > culm-sheaths > young panicles at the filling stage, with the Bt protein levels in all the above tissues consistently higher than those in brown rice at the full ripening stage. In conclusion, the transcription levels of the cry2A* gene in early japonica rice were significantly positively correlated with the Bt protein expression levels, with distinct temporal and spatial variations. Collectively, the expression increased with the progression of growth and development in vegetative organs, while it decreased with the advance of growth stages in reproductive organs.

Key words: cry2A*-transgenic early japonica rice, ‘Songjing 9 (cry2A*)’, qPCR technology, ELISA technology, Bt protein expression levels, temporal and spatial expression