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  - Ma, Xuemin
A1  - Balazadeh, Salma
A1  - Mueller-Roeber, Bernd
T1  - Tomato fruit ripening factor NOR controls leaf senescence
JF  - Journal of experimental botany
N2  - NAC transcription factors (TFs) are important regulators of expressional reprogramming during plant development, stress responses, and leaf senescence. NAC TFs also play important roles in fruit ripening. In tomato (Solanum lycopersicum), one of the best characterized NACs involved in fruit ripening is NON-RIPENING (NOR), and the non-ripening (nor) mutation has been widely used to extend fruit shelf life in elite varieties. Here, we show that NOR additionally controls leaf senescence. Expression of NOR increases with leaf age, and developmental as well as dark-induced senescence are delayed in the nor mutant, while overexpression of NOR promotes leaf senescence. Genes associated with chlorophyll degradation as well as senescence-associated genes (SAGs) show reduced and elevated expression, respectively, in nor mutants and NOR overexpressors. Overexpression of NOR also stimulates leaf senescence in Arabidopsis thaliana. In tomato, NOR supports senescence by directly and positively regulating the expression of several senescence-associated genes including, besides others, SlSAG15 and SlSAG113, SlSGR1, and SlYLS4. Finally, we find that another senescence control NAC TF, namely SlNAP2, acts upstream of NOR to regulate its expression. Our data support a model whereby NAC TFs have often been recruited by higher plants for both the control of leaf senescence and fruit ripening.
KW  - Aging
KW  - leaf
KW  - NAC
KW  - non-ripening
KW  - NOR
KW  - senescence
KW  - tomato
KW  - transcription factor
Y1  - 2019
U6  - https://doi.org/10.1093/jxb/erz098
SN  - 0022-0957
SN  - 1460-2431
VL  - 70
IS  - 10
SP  - 2727
EP  - 2740
PB  - Oxford Univ. Press
CY  - Oxford
ER  -