Protein storage vacuoles (PSV) are the main repository of protein in dicotyledonous seeds. Little is known about the origins of these transient organelles. PSV are hypothesised to either arise de novo or to originate from the pre-existing embryonic vacuole (EV) during seed maturation. We have tested these hypotheses by studying PSV formation in Arabidopsis embryos at different stages of seed maturation and have recapitulated this process in Arabidopsis leaves reprogrammed to an embryogenic fate by inducing expression of the LEAFY COTYLEDON2 transcription factor. Confocal and immunoelectron microscopy indicate that both storage proteins and tonoplast proteins typical of PSV are delivered to the pre-existing EV in embryos or to the lytic vacuole in reprogrammed leaf cells. In addition, sectioning through embryos at several developmental stages using serial block face scanning electron microscopy reveals the 3D architecture of forming PSV. Our results indicate that in Arabidopsis the pre-existing vacuole is reprogrammed to become a PSV.
Feeney, MistianneKittelmann, Maike Menassa, RimaHawes, Chris Frigerio, Lorenzo
Faculty of Health and Life Sciences\Department of Biological and Medical Sciences
Year of publication: 2018Date of RADAR deposit: 2018-03-16