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Nat Genet. 2015 Dec;47(12):1489-93. doi: 10.1038/ng.3422. Epub 2015 Nov 2.

Seed filling in domesticated maize and rice depends on SWEET-mediated hexose transport.

Author information

1
Department of Plant Biology, Carnegie Science, Stanford, California, USA.
2
Department of Genetics, Development and Cell Biology, Iowa State University, Ames, Iowa, USA.
3
US Department of Agriculture, Agricultural Research Service (USDA-ARS), Gainesville, Florida, USA.
4
Department of Plant Sciences, University of California, Davis, Davis, California, USA.
5
Ecole Normale Supérieure de Lyon, Université Lyon 1, Unité Reproduction et Développement des Plantes, Lyon, France.
6
Plant Molecular and Cellular Biology, Agronomy Department, University of Florida, Gainesville, Florida, USA.
7
Department of Plant Sciences, Center for Population Biology and Genome Center, University of California, Davis, Davis, California, USA.

Abstract

Carbohydrate import into seeds directly determines seed size and must have been increased through domestication. However, evidence of the domestication of sugar translocation and the identities of seed-filling transporters have been elusive. Maize ZmSWEET4c, as opposed to its sucrose-transporting homologs, mediates transepithelial hexose transport across the basal endosperm transfer layer (BETL), the entry point of nutrients into the seed, and shows signatures indicative of selection during domestication. Mutants of both maize ZmSWEET4c and its rice ortholog OsSWEET4 are defective in seed filling, indicating that a lack of hexose transport at the BETL impairs further transfer of sugars imported from the maternal phloem. In both maize and rice, SWEET4 was likely recruited during domestication to enhance sugar import into the endosperm.

PMID:
26523777
DOI:
10.1038/ng.3422
[Indexed for MEDLINE]

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