Transcription factors regulating leaf senescence in Arabidopsis thaliana

Abstract

Senescence is a highly regulated process, eventually leading to cell and tissue disintegration: a physiological process associated with nutrient (e.g. nitrogen) redistribution from leaves to reproductive organs. Senescence is not observed in young leaves, indicating that repressors efficiently act to suppress cell degradation during early leaf development and/or that senescence activators are switched on when a leaf ages. Thus, massive regulatory network re‐wiring likely constitutes an important component of the pre‐senescence process. Transcription factors (TFs) have been shown to be central elements of such regulatory networks. Here, we used quantitative real‐time polymerase chain reaction (qRT‐PCR) analysis to study the expression of 1880 TF genes during pre‐senescence and early‐senescence stages of leaf development, using Arabidopsis thaliana as a model. We show that the expression of 185 TF genes changes when leaves develop from half to fully expanded leaves and finally enter partial senescence. Our analysis identified 41 TF genes that were gradually up‐regulated as leaves progressed through these developmental stages. We also identified 144 TF genes that were down‐regulated during senescence. A considerable number of the senescence‐regulated TF genes were found to respond to abiotic stress, and salt stress appeared to be the major factor controlling their expression. Our data indicate a peculiar fine‐tuning of developmental shifts during late‐leaf development that is controlled by TFs.

Update on the biochemistry of chlorophyll breakdown

“…SGR, NYC1, PPH, PAO and MES16 (Ren et al 2007(Ren et al , 2010Schelbert et al 2009;Pružinská et al 2005;Horie et al 2009;Christ et al 2012) are highly coregulated in Arabidopsis and consequently cluster closely together when performing gene network analyses, for example using the ATTEDII platform (Obayashi et al 2009). Possibly, among the hundreds of transcription factors that have been shown to be up-regulated during leaf senescence (Balazadeh et al 2008) are some that specifically target the PAO pathway, but these have so far not been identified.…”

Comprehensive Dissection of Spatiotemporal Metabolic Shifts in Primary, Secondary, and Lipid Metabolism during Developmental Senescence in Arabidopsis

“…SAGs encoding hydrolytic enzymes as well as transporters have been identified to be responsible for either the degradation or mobilization of the various macromolecules and breakdown products. In addition, many transcription factors are expressed that coordinate this complex developmental process (Nam, 1997;Lers et al, 1998;Thompson et al, 1998;Rubinstein, 2000;Bhalerao et al, 2003;Buchanan-Wollaston et al, 2003, 2005Gepstein et al, 2003;Yoshida, 2003;Guo et al, 2004;Balazadeh et al, 2008). As well as developmental leaf senescence, adverse biotic or abiotic conditions can interfere with or induce senescence (Gregersen et al, 2013).…”

The Single-Stranded DNA-Binding Protein WHIRLY1 Represses WRKY53 Expression and Delays Leaf Senescence in a Developmental Stage-Dependent Manner in Arabidopsis

“…Early expression profiling and transcriptome analyses have revealed that a big portion of specific transcription factors are reprogrammed during leaf senescence (Chen et al, 2002;BuchananWollaston et al, 2003BuchananWollaston et al, , 2005Guo et al., 2004;Zentgraf et al., 2004;Balazadeh et al., 2008;Breeze et al, 2011). These transcription factors are characterized in the protein families NAC, WRKY, MYB, C2H2 zinc finger, bZIP, and AP2/EREBP.…”