Abstract：Sugarcane (Saccharum officinarum) is an allopolyploid crop, and its complex genetic background leads to a more complex regulation mechanism of sugarcane genes. The ScGAI (sugarcane gibberellic acid insensitive) gene encodes a DELLA protein involved in sugarcane stem development. Previous studies of our research group's found that the ScGAI gene is located on Chr 1B and Chr 1C chromosomes of S. spontaneum genome, and is regulated by 2 promoters with different lengths. Sequence analysis showed that the main difference in the upstream 1.1 kb regions of the 2 promoters was that compared with the more extended promoter, there were 2 fragment deletions in the -982~-496 region of the shorter promoter. The prediction of cis-acting regulatory elements in this study found that the deleted fragment contained multiple cis-acting elements related to expression regulation, such as TATA-box and CAAT-box. Thus, the 2 promoters of the ScGAI gene might have different regulation effects on ScGAI expression. The plant expression vectors of the β-glucuronidase (GUS) gene driven by the promoters of the ScGAI gene or maize (Zea mays) ubiquitin (UBI) gene were constructed and transferred into Arabidopsis thaliana. GUS staining analysis of T3 transgenic Arabidopsis thaliana at different growth stages and tissues showed that the longer ScGAI gene promoter was expressed in all tissues of Arabidopsis thaliana. In contrast, the shorter ScGAI gene promoter was mainly expressed in leaf veins and weakly expressed in roots and stems. This study provides important scientific basis for the subsequent functional study of the ScGAI gene.
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