Identification of the Core Pollen-Specific Regulation in the Rice OsSUT3 Promoter.

Dandan Li,Hong Yang,Chengyun Li,Dong Lv,Rucong Xu,Jiancheng Wen,Jianbo Zhang,Xuelin Tan,Chunlong Zhang

doi:10.3390/ijms21061909

Abstract

The regulatory mechanisms of pollen development have potential value for applications in agriculture, such as better understanding plant reproductive regularity. Pollen-specific promoters are of vital importance for the ectopic expression of functional genes associated with pollen development in plants. However, there is a limited number of successful applications using pollen-specific promoters in genetic engineering for crop breeding and hybrid generation. Our previous work led to the identification and isolation of the OsSUT3 promoter from rice. In this study, to analyze the effects of different putative regulatory motifs in the OsSUT3 promoter, a series of promoter deletions were fused to a GUS reporter gene and then stably introduced into rice and Arabidopsis. Histochemical GUS analysis of transgenic plants revealed that p385 (from −385 to −1) specifically mediated maximal GUS expression in pollen tissues. The S region (from −385 to −203) was the key region for controlling the pollen-specific expression of a downstream gene. The E1 (−967 to −606), E2 (−202 to −120), and E3 (−119 to −1) regions enhanced ectopic promoter activity to different degrees. Moreover, the p385 promoter could alter the expression pattern of the 35S promoter and improve its activity when they were fused together. In summary, the p385 promoter, a short and high-activity promoter, can function to drive pollen-specific expression of transgenes in monocotyledon and dicotyledon transformation experiments.

Highlights

Promoters, the upstream sequences of the gene coding sequences, are important molecular biological tools that play a crucial role in the regulation of expression of target genes
The GUS expression in the panicles of p385::GUS lines, 52.19% of the level of that of 35S::GUS plants, was significantly weaker. These results indicated that the p385 region of the OsSUT3 promoter was effective for expressing a downstream gene in a pollen-specific manner, despite the gene expression level being observably decreased compared to the level as a gene driven by the 35S promoter
We found that p385 adjacent to the 35S promoter worked as a directed promoter with pollen specificity. p385 altered the 35S promoter characteristics, which constitutively expressed the GUS gene in all tested organs or tissues and guided the promoter activity only in pollen tissue

Summary

Introduction

The upstream sequences of the gene coding sequences, are important molecular biological tools that play a crucial role in the regulation of expression of target genes. This region harbors many cis-elements influencing the expression of a downstream gene, for example, 5 untranslated region (5 UTR). Constitutive promoters, which drive the expression of target genes uniformly in most parts of a host plant, are commonly used as a means to introduce genes of interest in cereals crops, such as the CaMV35S [1], actin [2], and maize ubiquitin [3] promoters. Pollen-specific promoters are extremely useful tools for studying pollen development by molecular genetics and have quickened molecular breeding with male sterile lines [11]

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Methods

Conclusion