TY  - JOUR
A1  - Kamranfar, Iman
A1  - Xue, Gang-Ping
A1  - Tohge, Takayuki
A1  - Sedaghatmehr, Mastoureh
A1  - Fernie, Alisdair R.
A1  - Balazadeh, Salma
A1  - Mueller-Roeber, Bernd
T1  - Transcription factor RD26 is a key regulator of metabolic reprogramming during dark-induced senescence
JF  - New phytologist : international journal of plant science
N2  - Leaf senescence is a key process in plants that culminates in the degradation of cellular constituents and massive reprogramming of metabolism for the recovery of nutrients from aged leaves for their reuse in newly developing sinks. We used molecular-biological and metabolomics approaches to identify NAC transcription factor (TF) RD26 as an important regulator of metabolic reprogramming in Arabidopsis thaliana. RD26 directly activates CHLOROPLAST VESICULATION (CV), encoding a protein crucial for chloroplast protein degradation, concomitant with an enhanced protein loss in RD26 over-expressors during senescence, but a reduced decline of protein in rd26 knockout mutants. RD26 also directly activates LKR/SDH involved in lysine catabolism, and PES1 important for phytol degradation. Metabolic profiling revealed reduced c-aminobutyric acid (GABA) in RD26 overexpressors, accompanied by the induction of respective catabolic genes. Degradation of lysine, phytol and GABA is instrumental for maintaining mitochondrial respiration in carbon-limiting conditions during senescence. RD26 also supports the degradation of starch and the accumulation of mono-and disaccharides during senescence by directly enhancing the expression of AMY1, SFP1 and SWEET15 involved in carbohydrate metabolism and transport. Collectively, during senescence RD26 acts by controlling the expression of genes across the entire spectrum of the cellular degradation hierarchy.
KW  - Arabidopsis
KW  - fatty acid
KW  - primary metabolism
KW  - protein and amino acid degradation
KW  - respiration
KW  - senescence
Y1  - 2018
U6  - https://doi.org/10.1111/nph.15127
SN  - 0028-646X
SN  - 1469-8137
VL  - 218
IS  - 4
SP  - 1543
EP  - 1557
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Matallana-Ramirez, Lilian P.
A1  - Rauf, Mamoona
A1  - Farage-Barhom, Sarit
A1  - Dortay, Hakan
A1  - Xue, Gang-Ping
A1  - Droege-Laser, Wolfgang
A1  - Lers, Amnon
A1  - Balazadeh, Salma
A1  - Müller-Röber, Bernd
T1  - NAC Transcription Factor ORE1 and Senescence-Induced BIFUNCTIONAL NUCLEASE1 (BFN1) Constitute a Regulatory Cascade in Arabidopsis
JF  - Molecular plant
N2  - The NAC transcription factor ORE1 is a key regulator of senescence in Arabidopsis thaliana. Here, we demonstrate that senescence-induced and cell death-associated BIFUNCTIONAL NUCLEASE1 (BFN1) is a direct downstream target of ORE1, revealing a previously unknown regulatory cascade.Senescence is a highly regulated process that involves the action of a large number of transcription factors. The NAC transcription factor ORE1 (ANAC092) has recently been shown to play a critical role in positively controlling senescence in Arabidopsis thaliana; however, no direct target gene through which it exerts its molecular function has been identified previously. Here, we report that BIFUNCTIONAL NUCLEASE1 (BFN1), a well-known senescence-enhanced gene, is directly regulated by ORE1. We detected elevated expression of BFN1 already 2 h after induction of ORE1 in estradiol-inducible ORE1 overexpression lines and 6 h after transfection of Arabidopsis mesophyll cell protoplasts with a 35S:ORE1 construct. ORE1 and BFN1 expression patterns largely overlap, as shown by promoterreporter gene (GUS) fusions, while BFN1 expression in senescent leaves and the abscission zones of maturing flower organs was virtually absent in ore1 mutant background. In vitro binding site assays revealed a bipartite ORE1 binding site, similar to that of ORS1, a paralog of ORE1. A bipartite ORE1 binding site was identified in the BFN1 promoter; mutating the cis-element within the context of the full-length BFN1 promoter drastically reduced ORE1-mediated transactivation capacity in transiently transfected Arabidopsis mesophyll cell protoplasts. Furthermore, chromatin immunoprecipitation (ChIP) demonstrates in vivo binding of ORE1 to the BFN1 promoter. We also demonstrate binding of ORE1 in vivo to the promoters of two other senescence-associated genes, namely SAG29/SWEET15 and SINA1, supporting the central role of ORE1 during senescence.
KW  - Arabidopsis thaliana
KW  - senescence
KW  - transcription factor
KW  - ORE1
KW  - BFN1
KW  - promoter
Y1  - 2013
U6  - https://doi.org/10.1093/mp/sst012
SN  - 1674-2052
VL  - 6
IS  - 5
SP  - 1438
EP  - 1452
PB  - Oxford Univ. Press
CY  - Oxford
ER  -