Salicylic acid dependent signaling promotes basal thermotolerance but is not essential for acquired thermotolerance in <i>Arabidopsis thaliana</i>

Clarke, Shannon; Mur, Luis A. J.; Wood, Jackie E; Scott, Ian M.

doi:10.1111/j.1365-313x.2004.02054.x

Cited by 312 publications

(264 citation statements)

References 78 publications

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“…HS was found to induce SA-regulated pathogenesis-related 1 (PR1) transcripts, and the constitutive expression of PR1 protein mutant (cpr1-5) exhibited an enhanced thermotolerant phenotype (Clarke et al, 2004;. This indicates that SA and PR1, originally defined as being involved in antipathogenic responses, can also promote heat tolerance in A. thaliana.…”

Section: Introductionmentioning

confidence: 94%

“…Electrolyte leakage measurements Measurement of leaf electrolyte leakage (EL) was carried out essentially as described by Clarke et al (2004). For experiments where EL was measured during heat treatment at 42°C, the aerial parts of 3-week-old plants were placed into glass tubes containing 5 ml of water and incubated in a waterbath at 42°C in the dark.…”

Section: Heat Stress Treatmentsmentioning

confidence: 99%

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Functional Characterization of Arabidopsis thaliana WRKY39 in Heat Stress

Zhou

Chen

et al. 2010

Molecules and Cells

206

127

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Arabidopsis thaliana WRKY39, a transcription factor that is induced by heat stress, is a member of the group II WRKY proteins and responds to both abiotic and biotic stress. Heat-treated seeds and plants of WRKY39 knock-down mutants had increased susceptibility to heat stress, showing reduced germination, decreased survival, and elevated electrolyte leakage compared with wild-type plants. In contrast, WRKY39 over-expressing plants exhibited enhanced thermotolerance compared with wild-type plants. RT-PCR and qRT-PCR analysis of wrky39 mutants and WRKY39 over-expressing plants identified putative genes regulated by WRKY39. Consistent with a role for WRKY39 in heat tolerance, the expression levels of salicylic acid (SA)-regulated PR1 and SA-related MBF1c genes were downregulated in wrky39 mutants. In contrast, over-expression of WRKY39 increased the expression of PR1 and MBF1c. The WRKY39 transcript was induced in response to treatment with SA or methyljasmonate. Analysis of heat stressinduced WRKY39 in defense signaling mutants, including coi1, ein2, and sid2, further indicated that WRKY39 was positively co-regulated by the SA and jasmonate (JA) signaling pathways. Together, these findings reveal that heat stress-induced WRKY39 positively regulates the cooperation between the SA-and JA-activated signaling pathways that mediate responses to heat stress.

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Section: Introductionmentioning

confidence: 94%

Section: Heat Stress Treatmentsmentioning

confidence: 99%

Functional Characterization of Arabidopsis thaliana WRKY39 in Heat Stress

Zhou

Chen

et al. 2010

Molecules and Cells

206

127

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“…Previous studies have shown that heat shock transcription factors (HSFs) 2 play an important role in thermotolerance in plants and other organisms, regulating heat shock proteins (HSPs) as well as different acclimation and detoxification proteins (7)(8)(9)(10). In contrast, although several other pathways, involving ethylene, salicylic acid (SA), and trehalose, have recently been proposed to play an important role in thermotolerance in plants (5,(11)(12)(13)(14)(15), a key regulator of these responses was not identified.…”

mentioning

confidence: 99%

The Transcriptional Co-activator MBF1c Is a Key Regulator of Thermotolerance in Arabidopsis thaliana

Suzuki

Bajad

Shuman

et al. 2008

Journal of Biological Chemistry

256

249

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The ability of an organism to acclimate to its environment is a key determinant in its global distribution and capacity to compete with other organisms. The heat stress response, a highly conserved environmental and developmental program in eukaryotic and prokaryotic organisms, is an important component of the acclimation response of plants. Previous studies have shown that heat shock transcription factors play an important role in thermotolerance in plants and other organisms, controlling the expression of different heat shock proteins and detoxifying enzymes. In contrast, although several other pathways, involving ethylene, salicylic acid (SA), and trehalose, were recently shown to play a central role in thermotolerance in plants, a key regulator of these responses was not identified. Here we report that the highly conserved transcriptional coactivator, MBF1c (multiprotein bridging factor 1c), is a key regulator of thermotolerance in Arabidopsis thaliana. MBF1c protein accumulates rapidly and is localized to nuclei during heat stress. MBF1c is required for thermotolerance and functions upstream to SA, trehalose, ethylene, and pathogenesis-related protein 1 during heat stress. In contrast, MBF1c is not required for the expression of transcripts encoding HSFA2 and different heat shock proteins. Interestingly, MBF1c interacts with TPS5 (trehalose phosphate synthase 5), which is also heat-inducible, and mutants deficient in TPS5 are thermosensitive. Our results provide evidence for the existence of a tightly coordinated heat stress-response network, involving trehalose-, SA-, and ethylene-signaling pathways, that is under the control of MBF1c.Thermotolerance is an essential component of the acclimation response of different organisms (1-6). It is generally divided into acquired thermotolerance (i.e. the ability to acquire tolerance to otherwise lethal heat stress) and basal thermotolerance (i.e. the inherent ability to survive temperature above the optimal growth) (5). Previous studies have shown that heat shock transcription factors (HSFs) 2 play an important role in thermotolerance in plants and other organisms, regulating heat shock proteins (HSPs) as well as different acclimation and detoxification proteins (7-10). In contrast, although several other pathways, involving ethylene, salicylic acid (SA), and trehalose, have recently been proposed to play an important role in thermotolerance in plants (5, 11-15), a key regulator of these responses was not identified.MBF1 (multiprotein bridging factor 1) is a highly conserved transcriptional co-activator involved in the regulation of diverse processes, such as endothelial cell differentiation, hormone-regulated lipid metabolism, central nervous system development, and histidine metabolism (16 -19). MBF1 proteins from different organisms interact with transcription factors, such as c-Jun, GCN4, and ATF1, or with different hormone receptors and link them with the TATA-binding protein (16 -20). The flowering plant Arabidopsis thaliana contains three different genes e...

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“…Over the past few years, a more general role for SA as a mediator of diverse stress responses has been emerging. For example, in Arabidopsis SA is synthesized in response to abiotic stresses such as UV-C (30), ozone (31), cold (32), and heat (33,34) and has been shown to play a role in stress-induced developmental transitions, including flowering (35) and senescence (36). Although AtICS1 has been confirmed to be involved in many of these processes, it has only been implicated in others, such as cold-tolerant growth.…”

mentioning

confidence: 99%

Arabidopsis Isochorismate Synthase Functional in Pathogen-induced Salicylate Biosynthesis Exhibits Properties Consistent with a Role in Diverse Stress Responses

Strawn

Marr

Inoue

et al. 2007

Journal of Biological Chemistry

217

146

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Salicylic acid (SA) is a phytohormone best known for its role in plant defense. It is synthesized in response to diverse pathogens and responsible for the large scale transcriptional induction of defense-related genes and the establishment of systemic acquired resistance. Surprisingly, given its importance in plant defense, an understanding of the underlying enzymology is lacking. In Arabidopsis thaliana, the pathogen-induced accumulation of SA requires isochorismate synthase (AtICS1). Here, we show that AtICS1 is a plastid-localized, stromal protein using chloroplast import assays and immunolocalization. AtICS1 acts as a monofunctional isochorismate synthase (ICS), catalyzing the conversion of chorismate to isochorismate (IC) in a reaction that operates near equilibrium (K eq ‫؍‬ 0.89). It does not convert chorismate directly to SA (via an IC intermediate) as does Yersinia enterocolitica Irp9. Using an irreversible coupled spectrophotometric assay, we found that AtICS1 exhibits an apparent K m of 41.5 M and k cat ‫؍‬ 38.7 min ؊1 for chorismate. This affinity for chorismate would allow it to successfully compete with other pathogen-induced, chorismate-utilizing enzymes. Furthermore, the biochemical properties of AtICS1 indicate its activity is not regulated by light-dependent changes in stromal pH, Mg 2؉ , or redox and that it is remarkably active at 4°C consistent with a role for SA in cold-tolerant growth. Finally, our analyses support plastidic synthesis of stress-induced SA with the requirement for one or more additional enzymes responsible for the conversion of IC to SA, because non-enzymatic conversion of IC to SA under physiological conditions was negligible.

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Salicylic acid dependent signaling promotes basal thermotolerance but is not essential for acquired thermotolerance in Arabidopsis thaliana

Cited by 312 publications

References 78 publications

Functional Characterization of Arabidopsis thaliana WRKY39 in Heat Stress

Functional Characterization of Arabidopsis thaliana WRKY39 in Heat Stress

The Transcriptional Co-activator MBF1c Is a Key Regulator of Thermotolerance in Arabidopsis thaliana

Arabidopsis Isochorismate Synthase Functional in Pathogen-induced Salicylate Biosynthesis Exhibits Properties Consistent with a Role in Diverse Stress Responses

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