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Zm ZHOUPI , an endosperm‐specific basic helix–loop–helix transcription factor involved in maize seed development
Author(s) -
Grimault Aurélie,
Gendrot Ghislaine,
Chamot Sophy,
Widiez Thomas,
Rabillé Hervé,
Gérentes MarieFrance,
Creff Audrey,
Thévenin Johanne,
Dubreucq Bertrand,
Ingram Gwyneth C.,
Rogowsky Peter M.,
DepègeFargeix Nathalie
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13024
Subject(s) - endosperm , biology , arabidopsis , embryo , gene , transcription factor , microbiology and biotechnology , arabidopsis thaliana , genetics , mutant , transcription (linguistics) , ectopic expression , linguistics , philosophy
Summary In angiosperm seeds the embryo is embedded within the endosperm, which is in turn enveloped by the seed coat, making inter‐compartmental communication essential for coordinated seed growth. In this context the basic helix–loop–helix domain transcription factor At ZHOUPI (At ZOU ) fulfils a key role in both the lysis of the transient endosperm and in embryo cuticle formation in Arabidopsis thaliana . In maize ( Zea mays ), a cereal with a persistent endosperm, a single gene, Zm ZOU , falls into the same phylogenetic clade as At ZOU . Its expression is limited to the endosperm where it peaks during the filling stage. In Zm ZOU ‐ RNA interference knock‐down lines embryo size is slightly reduced and the embryonic suspensor and the adjacent embryo surrounding region show retarded breakdown. Ectopic expression of Zm ZOU reduces stomatal number, possibly due to inappropriate protein interactions. Zm ZOU forms functional heterodimers with At ICE /At SCREAM and the closely related maize proteins Zm ICE b and Zm ICE c, but its interaction is more efficient with the Zm ICE a protein, which shows sequence divergence and only has close homologues in other monocotyledonous species. Consistent with the observation that these complexes can trans‐ activate target gene promoters from Arabidopsis, Zm ZOU partially complements the Atzou‐4 mutant. However, structural, trans ‐activation and gene expression data support the hypothesis that Zm ZOU and Zm ICE a may have coevolved to form a functional complex unique to monocot seeds. This divergence may explain the reduced functionality of Zm ZOU in Arabidopsis, and reflect functional specificities which are unique to the monocotyledon lineage.