524 / 2019-03-04 19:54:35

Maternal control of seed size by regulating ABI5 stability in Arabidopsis

seed development,endosperm cellularization,maternal effect,abscisic acid,seed size

Growth and Development > Growth and Development

In flowering plants, seed development is crucial because it determines not only the plant survival but also the crop yield. During the early stage of seed development in Arabidopsis, ABA from the maternal plants accumulates to a high level in young seeds, and is known to affect the timing of endosperm cellularization and hence seed size. ABA INSENSITIVE 5 (ABI5) is a crucial factor in the ABA signaling pathway and its loss-of-function mutant produces large seeds. Here, we isolate a large seed size1 mutant (lss1), which has a maternal effect on determining seed size by controlling endosperm cellularization. The loss of function of LSS1 results in large seeds with delayed endosperm cellularization. We further show that LSS1 interacts with ABI5 during seed development. In vivo degradation assay demonstrates that LSS1 enhances the protein stability of ABI5. Thus, LSS1 integrates ABA signal from the maternal plants in regulating the endosperm cellularization, thereby affecting the final seed size.