title: SALT-RESPONSIVE ERF1 is a negative regulator of grain filling and gibberellin-mediated seedling establishment in rice.
abstract: Grain quality is an important agricultural trait that is mainly determined by grain size and composition. Here, we characterize the role of the rice transcription factor (TF) SALT-RESPONSIVE ERF1 (SERF1) during grain development. Through genome-wide expression profiling and chromatin immunoprecipitation, we found that SERF1 directly regulates RICE PROLAMIN-BOX BINDING FACTOR (RPBF), a TF that functions as a positive regulator of grain filling. Loss of SERF1 enhances RPBF expression resulting in larger grains with increased starch content, while SERF1 overexpression represses RPBF resulting in smaller grains. Consistently, during grain filling, starch biosynthesis genes such as GRANULE-BOUND STARCH SYNTHASEI (GBSSI), STARCH SYNTHASEI (SSI), SSIIIa, and ADP-GLUCOSE PYROPHOSPHORYLASE LARGE SUBUNIT2 (AGPL2) are up-regulated in SERF1 knockout grains. Moreover, SERF1 is a direct upstream regulator of GBSSI. In addition, SERF1 negatively regulates germination by controlling RPBF expression, which mediates the gibberellic acid (GA)-induced expression of RICE AMYLASE1A (RAmy1A). Loss of SERF1 results in more rapid seedling establishment, while SERF1 overexpression has the opposite effect. Our study reveals that SERF1 represents a negative regulator of grain filling and seedling establishment by timing the expression of RPBF.
authors.affiliation: Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany.
authors.forename: Romy
authors.initials: R
authors.lastname: Schmidt
authors.forename: Jos H M
authors.initials: JH
authors.lastname: Schippers
authors.forename: Delphine
authors.initials: D
authors.lastname: Mieulet
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Watanabe
authors.forename: Rainer
authors.initials: R
authors.lastname: Hoefgen
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Guiderdoni
authors.forename: Bernd
authors.initials: B
authors.lastname: Mueller-Roeber
mesh_terms: D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism*; D012275:Oryza / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013213:Starch / Q000096:biosynthesis
chemical_list: D005875:Gibberellins; D010940:Plant Proteins; D012097:Repressor Proteins; D013213:Starch; C007842:gibberellic acid
keywords: RPBF; SERF1; germination; gibberellic acid; grain filling; rice