A Cascade of Sequentially Expressed Sucrose Transporters in the Seed Coat and Endosperm Provides Nutrition for the Arabidopsis Embryo

• Published in: The Plant cell Vol. 27; no. 3; pp. 607 - 619
• Main Authors: Chen, Li-Qing, Lin, I Winnie, Qu, Xiao-Qing, Sosso, Davide, McFarlane, Heather E., Londoño, Alejandra, Samuels, A. Lacey, Frommer, Wolf B.
• Format: Journal Article
• Language: English
• Published: England American Society of Plant Biologists 01.03.2015
• Subjects: Animals; Arabidopsis; Arabidopsis - drug effects; Arabidopsis - embryology; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biological Transport - drug effects; Biological Transport - genetics; Embryogenesis; Embryos; Endosperm; Endosperm - genetics; Endosperm - metabolism; Gene Expression Regulation, Developmental - drug effects; Gene Expression Regulation, Plant - drug effects; Integument; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Models, Biological; mutants; Mutation - genetics; nutrition; Nutritional Physiological Phenomena - drug effects; Oocytes - metabolism; Organ Specificity - drug effects; Organ Specificity - genetics; Phenotype; Plant cells; Plant Leaves - drug effects; Plant Leaves - metabolism; Plant Roots - drug effects; Plant Roots - genetics; Plant Roots - growth & development; Plants; seed coat; seed yield; Seeds; Starch - metabolism; Starches; sucrose; Sucrose - metabolism; Sucrose - pharmacology; Sugars; Testa; Time Factors; tissues; transporters; Xenopus laevis
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.114.134585

Developing plant embryos depend on nutrition from maternal tissues via the seed coat and endosperm, but the mechanisms that supply nutrients to plant embryos have remained elusive. Sucrose, the major transport form of carbohydrate in plants, is delivered via the phloem to the maternal seed coat and then secreted from the seed coat to feed the embryo. Here, we show that seed filling in Arabidopsis thaliana requires the three sucrose transporters SWEET11, 12, and 15. SWEET11, 12, and 15 exhibit specific spatiotemporal expression patterns in developing seeds, but only a sweet11;12;15 triple mutant showed severe seed defects, which include retarded embryo development, reduced seed weight, and reduced starch and lipid content, causing a “wrinkled” seed phenotype. In sweet11;12;15 triple mutants, starch accumulated in the seed coat but not the embryo, implicating SWEET-mediated sucrose efflux in the transfer of sugars from seed coat to embryo. This cascade of sequentially expressed SWEETs provides the feeding pathway for the plant embryo, an important feature for yield potential.