Leaf senescence in Brassica napus: expression of genes encoding pathogenesis-related proteins

Hanfrey, Colin; Fife, M; Buchanan‐Wollaston, Vicky

doi:10.1007/bf00049334

Cited by 164 publications

(104 citation statements)

References 52 publications

(43 reference statements)

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“…Thus, it remains unclear whether this observed diVerence is due to variations of the experimental set-ups used or due to oV-target eVects of the silencing construct used, since the antisense line is phenotypically not identical to the Atwrky70 mutant plants (Li et al 2006). Still, several defense-related genes are known to be induced during leaf senescence, including PR1, PR2, PR3 and PDF1.2 (Wyatt et al 1991;Hanfrey et al 1996;Morris et al 2000;Quirino et al 2000;He et al 2002), in a phenomenon known as Age-Related Resistance (Kus et al 2002). Expression of PR genes during senescence is probably linked to a protective function in aging leaves against invasion by opportunistic pathogens, thereby maintaining viability of the leaf until mobilization is complete and preventing infection of the rest of the plant (Kus et al 2002).…”

Section: Discussionmentioning

confidence: 99%

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

Ülker

Mukhtar

Somssich

2007

Planta

234

172

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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.

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Section: Discussionmentioning

confidence: 99%

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

Ülker

Mukhtar

Somssich

2007

Planta

234

172

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“…They are predicted to encode transcription factors (Eulgem et al, 2000;Hinderhofer and Zentgraf, 2001;Robatzek and Somssich, 2002), receptors for senescence perception (Hajouj et al, 2000;Robatzek and Somssich, 2002), and components of intracellular protein traf®cking (Guterman et al, 2003). Among the genes that are upregulated during leaf senescence are several whose transcript levels accumulate also under abiotic and biotic stresses (Binyamin et al, 2000;Hanfrey et al, 1996;John et al, 1997;Quirino et al, 1999;Weaver et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Large‐scale identification of leaf senescence‐associated genes

et al. 2003

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SummaryLeaf senescence is a form of programmed cell death, and is believed to involve preferential expression of a speci®c set of`senescence-associated genes' (SAGs). To decipher the molecular mechanisms and the predicted complex network of regulatory pathways involved in the senescence program, we have carried out a large-scale gene identi®cation study in a reference plant, Arabidopsis thaliana. Using suppression subtractive hybridization, we isolated approximately 800 cDNA clones representing SAGs expressed in senescing leaves. Differential expression was con®rmed by Northern blot analysis for 130 non-redundant genes. Over 70 of the identi®ed genes have not previously been shown to participate in the senescence process. SAGencoded proteins are likely to participate in macromolecule degradation, detoxi®cation of oxidative metabolites, induction of defense mechanisms, and signaling and regulatory events. Temporal expression pro®les of selected genes displayed several distinct patterns, from expression at a very early stage, to the terminal phase of the senescence syndrome. Expression of some of the novel SAGs, in response to age, leaf detachment, darkness, and ethylene and cytokinin treatment was compared. The large repertoire of SAGs identi®ed here provides global insights about regulatory, biochemical and cellular events occurring during leaf senescence.

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“…For example, some pathogenesis-related (PR) and PR-like genes are upregulated during flower development and senescence (Fraser, 1981;Lotan et al, 1989; Buchanan-Wollaston, 1994;Hanfrey et al, 1996; Butt et al, 1998;Quirino et al, 1999). Older leaves of flowering tobacco accumulate specific PR proteins (PR-1, PR-2, and PR-3), and this correlates with increased resistance to viral and fungal pathogens (Fraser, 1972;Takahashi, 1972;Reuveni et al, 1986;Wyatt et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Age-Related Resistance in Arabidopsis Is a Developmentally Regulated Defense Response to Pseudomonas syringae

et al. 2002

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Age-related resistance (ARR) has been observed in a number of plant species; however, little is known about the biochemical or molecular mechanisms involved in this response. Arabidopsis becomes more resistant, or less susceptible, to virulent Pseudomonas syringae (pv tomato or maculicola ) as plants mature (in planta bacterial growth reduction of 10-to 100-fold). An ARR-like response also was observed in response to certain environmental conditions that accelerate Arabidopsis development. ARR occurs in the Arabidopsis mutants pad3-1 , eds7-1 , npr1-1 , and etr1-4 , suggesting that ARR is a distinct defense response, unlike the induced systemic resistance or systemic acquired resistance responses. However, three salicylic acid (SA) accumulation-deficient plant lines, NahG , sid1 , and sid2 , did not exhibit ARR. A heat-stable antibacterial activity was detected in intercellular washing fluids in response to Pst inoculation in wild-type ARR-competent plants but not in NahG . These data suggest that the ability to accumulate SA is necessary for the ARR response and that SA may act as a signal for the production of the ARR-associated antimicrobial compound(s) and/or it may possess direct antibacterial activity against P. syringae . INTRODUCTIONThe relationship between plant age and disease resistance has been investigated in many plant-pathogen systems (Bateman and Lumsden, 1965; Griffey and Leach, 1965;Hunter et al., 1977;Lazarovits et al., 1981;Ward et al., 1981;Miller, 1983; Chase and Jones, 1986;Reuveni et al., 1986;Pretorius et al., 1988;Koch and Mew, 1991; Chang et al., 1992;Heath, 1993;Rupe and Gbur, 1995). Some plants become more susceptible to certain pathogens as they develop (Miller, 1983); however, susceptibility decreases with increasing leaf age in the rice/ Xanthomonas campestris pv oryzae (Koch and Mew, 1991) and rice/ Pyricularia oryzae (Roumen et al., 1992) interactions. In contrast, older plants (both young and mature leaves) display increased resistance in the wheat/ Puccinia recondita f.sp. tritici (Pretorius et al., 1988) and tobacco/ Peronospora tabacina (Reuveni et al., 1986) interactions. When older leaves/plants display increased resistance or reduced susceptibility to pathogens, this form of resistance often is referred to as age-related resistance (ARR).The actual mechanisms responsible for the different forms of ARR have been studied in a preliminary manner in only a few cases. In cowpea/rust and cereal/rust interactions, an ARR response is thought to be controlled by single resistance genes expressed in adult plants (Roelfs, 1984;Heath, 1993). Ward et al. (1981) and Lazarovits et al. (1981) observed a positive correlation between increasing plant age, glyceollin production, and resistance to Phytophthora megasperma var sojae in soybean. A similar correlation was observed for the accumulation of a cotton phytoalexin in response to Verticillium albo-atrum infection (Bell, 1969), constitutive accumulation of terpenoids in older cotton plants (Hunter et al., 1977), or capsidiol accumulati...

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Leaf senescence in Brassica napus: expression of genes encoding pathogenesis-related proteins

Cited by 164 publications

References 52 publications

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

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

Large‐scale identification of leaf senescence‐associated genes

Age-Related Resistance in Arabidopsis Is a Developmentally Regulated Defense Response to Pseudomonas syringae

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