Appropriate seed development in Arabidopsis involves the coordinated growth between embryo and endosperm. After endosperm cellularization, embryo growth accelerates, which suggests that sugar is reallocated from endosperm to embryo. Invertase, an enzyme that breaks down sucrose, has been shown to regulate the movement of sugar from maternal tissue to the endosperm. Our lab identified an invertase inhibitor (InvINH1) expressed in the endosperm before cellularization. When ZOU promoter was used to express InvINH1 in the cellularized endosperm, a subtle delay in embryo growth was observed. To validate this phenotype, a stronger promoter from RGP3 was used to drive the expression of InvINH1. RGP3 is an enzyme essential for the formation of the plant cell wall. To ectopically express InvINH1, RGP3 promoter was the first cloned in front of the InvINH1 coding region to create construct pRGP3-InvINH1. To confirm the expression pattern of RGP3 promoter, the promoter was also cloned in front of the coding region of a green flourescent protein. Both constructs were transformed into Arabidopsis. After transgenic plants carrying pRGP3-InvINH1 transgene are identified, detailed phenotypic analysis will be carried out to determine whether pRGP3-InvINH1 could enhance the delayed embryo growth phenotype.
