MYB118 Represses Endosperm Maturation in Seeds of Arabidopsis

• Published in: The Plant cell Vol. 26; no. 9; pp. 3519 - 3537
• Main Authors: Barthole, Guillaume, To, Alexandra, Marchive, Chloé, Brunaud, Véronique, Soubigou-Taconnat, Ludivine, Berger, Nathalie, Dubreucq, Bertrand, Lepiniec, Loïc, Baud, Sébastien
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01.09.2014; American Society of Plant Biologists (ASPB)
• Subjects: Arabidopsis; Arabidopsis - embryology; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Base Sequence; Biochemistry, Molecular Biology; Botanics; Complementary DNA; Development Biology; Developmental biology; Embryology and Organogenesis; Embryos; Endosperm; Endosperm - embryology; Endosperm - genetics; Endosperm - metabolism; Fatty acids; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes; Genes, Plant; Genomics; Life Sciences; Messenger RNA; Molecular Sequence Data; Mutation - genetics; Plant cells; Plants; Protein Binding - genetics; Seed maturation; Transcription Factors - genetics; Transcription Factors - metabolism; Transcriptional Activation - genetics; Vegetal Biology; EMBRYO DEVELOPMENT; DNA-BINDING; DOMAIN; OIL; THALIANA; GENE-EXPRESSION; PLANTS; DEVELOPMENTAL REGULATION; ABSCISIC-ACID; TRANSCRIPTIONAL REGULATION
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.114.130021

In the exalbuminous species Arabidopsis thaliana, seed maturation is accompanied by the deposition of oil and storage proteins and the reduction of the endosperm to one cell layer. Here, we consider reserve partitioning between embryo and endosperm compartments. The pattern of deposition, final amount, and composition of these reserves differ between the two compartments, with the embryo representing the principal storage tissue in mature seeds. Complex regulatory mechanisms are known to prevent activation of maturation-related programs during embryo morphogenesis and, later, during vegetative growth. Here, we describe a regulator that represses the expression of maturation-related genes during maturation within the endosperm. MYB118 is transcriptionally induced in the maturing endosperm, and seeds of myb118 mutants exhibit an endosperm-specific derepression of maturation-related genes associated with a partial relocation of storage compounds from the embryo to the endosperm. Moreover, MYB118 activates endosperm-induced genes through the recognition of TAACGG elements. These results demonstrate that the differential partitioning of reserves between the embryo and endosperm in exalbuminous Arabidopsis seeds does not only result from developmental programs that establish the embryo as the preponderant tissue within seeds. This differential partitioning is also regulated by MYB118, which regulates the biosynthesis of reserves at the spatial level during maturation.