ArabidopsisNAC Transcription Factor JUNGBRUNNEN1 Exerts Conserved Control Over Gibberellin and Brassinosteroid Metabolism and Signaling Genes in Tomato.
TheArabidopsis thalianaNAC transcription factor JUNGBRUNNEN1 (AtJUB1) regulates growth by directly repressingGA3ox1andDWF4, two key genes involved in gibberellin (GA) and brassinosteroid (BR) biosynthesis, respectively, leading to GA and BR deficiency phenotypes. AtJUB1 also reduces the expression ofPIF4, a bHLH transcription factor that positively controls cell elongation, while it stimulates the expression ofDELLAgenes, which are important repressors of growth. Here, we extend our previous findings by demonstrating thatAtJUB1induces similar GA and BR deficiency phenotypes and changes in gene expression when overexpressed in tomato (Solanum lycopersicum). Importantly, and in accordance with the growth phenotypes observed, AtJUB1 inhibits the expression of growth-supporting genes, namely the tomato orthologs ofGA3ox1,DWF4andPIF4, but activates the expression ofDELLAorthologs, by directly binding to their promoters. Overexpression ofAtJUB1in tomato delays fruit ripening, which is accompanied by reduced expression of several ripening-related genes, and leads to an increase in the levels of various amino acids (mostly proline, β-alanine, and phenylalanine), γ-aminobutyric acid (GABA), and major organic acids including glutamic acid and aspartic acid. The fact that AtJUB1 exerts an inhibitory effect on the GA/BR biosynthesis andPIF4genes but acts as a direct activator ofDELLAgenes in both,Arabidopsisand tomato, strongly supports the model that the molecular constituents of the JUNGBRUNNEN1 growth control module are considerably conserved across species.
Institute of Biochemistry and Biology, University of Potsdam,Potsdam, Germany; Max Planck Institute of Molecular Plant Physiology,Potsdam, Germany.
Sara
S
Shahnejat-Bushehri
Institute of Biochemistry and Biology, University of Potsdam,Potsdam, Germany; Max Planck Institute of Molecular Plant Physiology,Potsdam, Germany.
Annapurna D
AD
Allu
Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany.
Nikolay
N
Mehterov
Institute of Biochemistry and Biology, University of Potsdam,Potsdam, Germany; Max Planck Institute of Molecular Plant Physiology,Potsdam, Germany.
Venkatesh P
VP
Thirumalaikumar
Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany.
Saleh
S
Alseekh
Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany.
Alisdair R
AR
Fernie
Institute of Biochemistry and Biology, University of Potsdam,Potsdam, Germany; Max Planck Institute of Molecular Plant Physiology,Potsdam, Germany.
Bernd
B
Mueller-Roeber
Institute of Biochemistry and Biology, University of Potsdam,Potsdam, Germany; Max Planck Institute of Molecular Plant Physiology,Potsdam, Germany.
Salma
S
Balazadeh
Arabidopsis; DELLA proteins; brassinosteroid; fruit; gibberellic acid; growth; tomato; transcription factor