Most angiosperms have nuclear endosperm, which consist of an initial syncytial phase and a cellularization phase. Before endosperm is fully cellularized, the embryo growth rate is relatively slow. Our work indicates that the expression of an Invertase inhibitor (InvINH1) during the syncytial phase correlates with the slow embryo growth rate. Since invertase is an enzyme that hydrolyzes sucrose into monosaccharides, we hypothesized that the expression of InvINH1 regulates sugar partition between the embryo and the endosperm during early seed development. To investigate which cis-elements are responsible for the specific expression of InvINH1 before endosperm cellularization, we performed a promoter-deletion analysis for the InvINH1 promoter. Eight promoter deletion constructs were designed to make deletions in 100-bp increment from the 5’ end of the InvINH1 promoter. The promoter regions containing deletions were PCR amplified and cloned in between XbaI and BamHI sites before the GUS reporter. The promoter deletion constructs will be verified by sequencing, and then used in expression analysis to identify regions of the promoter required for the expression of InvINH1 during the syncytial phase. By identifying the location of the cis-regulatory element, new connections can be made to further understand how InvINH1 expression is regulated during early seed development.
