The endosperm and embryo are the results of double fertilization in flowering plants. These structures rely on each other for successful seed development. In the early stages of Arabidopsis seed development, the endosperm grows rapidly while the embryo grows slowly. After endosperm cellularization, this growth pattern changes so that the endosperm grows slowly while the embryo grows quickly. This shift in growth is likely due to nutrients shifting from the endosperm to the embryo. We hypothesized that invertase, an enzyme that breaks down sucrose, is one of the primary mechanisms for this nutrient shift. Invertase Inhibitor 1 (InvINH1) was identified in our lab as being specifically expressed before endosperm cellularization. Therefore, the presence of InvINH1 is correlated with slow embryo growth. To further investigate the effects of InhINH1 on embryo growth rate, KRS promoter was selected to ectopically express InvINH1 after endosperm cellularization. The 2048bp KRS promoter region was amplified and cloned in front of InvINH1 coding region, creating the chimeric gene pKRS-InvINH1. For transgenic plants carrying pKRS-InvINH1, we expect to see a delay in embryo growth, which will support our hypothesis that the function of InvINH1 is to suppress embryo growth before endosperm cellularization.
