Dissecting conserved cis-regulatory modules of Glu-1 promoters which confer the highly active endosperm-specific expression via stable wheat transformation uri icon

abstract

  • Wheat high-molecular-weight glutenin subunits (HMW-GS) determine dough elasticity and play an essential role in processing quality. HMW-GS are encoded by Glu-1 genes and controlled primarily at transcriptional level, implemented through the interactions between cis-acting elements and trans-acting factors. However, transcriptional mechanismof Glu-1 genes remains elusive. Here we made a comprehensive analysis of cis-regulatory elements within 1-kb upstream of the Glu-1 start codon (-1000 to -1) and identified 30 conserved motifs. Based on motif distribution pattern, three conserved cis-regulatory modules (CCRMs), CCRM1 (-300 to -101), CCRM2 (-650 to -400), and CCRM3 (-950 to -750), were defined, and their functions were characterized in wheat stable transgenic lines transformed with progressive 5' deletion promoter::GUS fusion constructs. GUS staining, qPCR and enzyme activity assays indicated that CCRM2 and CCRM3 could enhance the expression level of Glu-1, whereas the 300-bp promoter (-300 to -1), spanning CCRM1 and core region (-100 to -1), was enough to ensure accurate Glu-1 initiation at 7 days after flowering (DAF) and shape its spatiotemporal expression pattern during seed development. Further transgenic assays demonstrated that CCRM1-2 (-300 to -209) containing CompleteHMWEnhancer (-246 to -209) was important for expression level but had no effect on expression specificity in the endosperm. In contrast, CCRM1-1 (-208 to -101) was critical for both expression specificity and level of Glu-1. Our findings not only provide new insights to uncover Glu-1 transcription regulatory machinery but also lay foundations for modifying Glu-1 expression. (C) 2018 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.

publication date

  • 2019
  • 2019