The WRKY70 transcription factor of Arabidopsis influences both the plant senescence and defense signaling pathways

Abstract

Regulatory proteins play critical roles in controlling the kinetics of various cellular processes during the entire life span of an organism. Leaf senescence, an integral part of the plant developmental program, is Wne-tuned by a complex transcriptional regulatory network ensuring a successful switch to the terminal life phase. To expand our understanding on how transcriptional control coordinates leaf senescence, we characterized AtWRKY70, a gene encoding a WRKY transcription factor that functions as a negative regulator of developmental senescence. To gain insight into the interplay of senescence and plant defense signaling pathways, we employed a collection of mutants, allowing us to speciWcally deWne the role of AtWRKY70 in the salicylic acid-mediated signaling cascades and to further dissect the cross-talk of signal transduction pathways during the onset of senescence in Arabidopsis thaliana. Our results provide strong evidence that AtWRKY70 inXuences plant senescence and defense signaling pathways. These studies could form the basis for further unraveling of these two complex interlinked regulatory networks.

Leaf Senescence Signaling: The Ca2+-Conducting Arabidopsis Cyclic Nucleotide Gated Channel2 Acts through Nitric Oxide to Repress Senescence Programming

“…(1) Prior studies (Poovaiah and Leopold, 1973;Chou and Kao, 1992;Corpas et al, 2004;Guo and Crawford, 2005;Mishina et al, 2007) discussed above suggest that both leaf Ca 2+ and NO repress leaf senescence. (2) High levels of SA and expression of PR1 are associated with treatments that reduce NO production in leaves and induce early senescence (Morris et al, 2000;Mishina et al, 2007;Ü lker, et al, 2007); SA level and PR1 expression are elevated in leaves of dnd1 plants (Yu et al, 1998). (3) Senescing leaves have reduced endogenous NO level .…”

“…Darkness treatment can induce senescence in detached leaves (Poovaiah and Leopold, 1973;Chou and Kao, 1992;Weaver and Amasino, 2001;Chrost et al, 2004;Guo and Crawford, 2005;Ü lker et al, 2007). Ca 2+ can delay the senescence of detached leaves (Poovaiah and Leopold, 1973) and leaf senescence induced by methyl jasmonate (Chou and Kao, 1992); the molecular events that mediate this effect of Ca 2+ are not well characterized at present.…”

The Ankyrin-Repeat Transmembrane Protein BDA1 Functions Downstream of the Receptor-Like Protein SNC2 to Regulate Plant Immunity

“…Arabidopsis (Arabidopsis thaliana) npr1-1, snc2-1D npr1-1, snc2-8, and wrky70-1 were described previously (Cao et al, 1994;Ulker et al, 2007;Zhang et al, 2010). Loss-of-function alleles of bda1 were identified from an ethyl methanesulfonate-mutagenized snc2-1D npr1-1 population by screening for mutants of increased size.…”

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

“…These transcription factors are characterized in the protein families NAC, WRKY, MYB, C2H2 zinc finger, bZIP, and AP2/EREBP. Among them, the NAC (Balazadeh et al, 2010(Balazadeh et al, , 2011 and WRKY (Miao et al, 2004;Ülker et al, 2007;Zentgraf et al, 2010;Zhou et al, 2011) family members have been proven to play central roles in controlling leaf senescence in Arabidopsis (Arabidopsis thaliana). Besides transcription factors, many other proteins with diverse functions, such as the activation domain (AD) protein , the epithiospecifying protein ESR/ESP , the SUVH2 histone methyltransferase (Ay et al, 2009), and the WHIRLY2 (WHY2) protein (Maréchal et al, 2008), have also been enumerated to participate in the regulation of plant senescence and cell death processes.…”