Divergent Roles in Arabidopsis thaliana Development and Defense of Two Homologous Genes, ABERRANT GROWTH AND DEATH2 and AGD2-LIKE DEFENSE RESPONSE PROTEIN1, Encoding Novel Aminotransferases

Song, Jong Tae; Lu, Hua; Greenberg, Jean T.

doi:10.1105/tpc.019372

Cited by 125 publications

(214 citation statements)

References 70 publications

(88 reference statements)

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“…Our data that eds1-2 and pad4-1 act nonadditively to suppress acd6-1-conferred phenotypes support the latter notion, suggesting that the two genes function in the same pathway to regulate plant defense and cell death in the acd6-1 background. ALD1 encodes an aminotransferase and was proposed to generate an amino acid-derived signal to activate plant defense (Song et al 2004a). Like npr1 mutants, ald1-1 is defective in both local defense and systemic acquired resistance (Song et al 2004b).…”

Section: Discussionmentioning

confidence: 99%

Genetic Dissection of Salicylic Acid-Mediated Defense Signaling Networks in Arabidopsis

Ng¹,

Seabolt²,

Zhang

et al. 2011

Genetics

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Properly coordinated defense signaling networks are critical for the fitness of plants. One hub of the defense networks is centered on salicylic acid (SA), which plays a key role in activating disease resistance in plants. However, while a number of genes are known to affect SA-mediated defense, relatively little is known about how these gene interact genetically with each other. Here we exploited the unique defense-sensitized Arabidopsis mutant accelerated cell death (acd) 6-1 to dissect functional relationships among key components in the SA hub. We show that while enhanced disease susceptibility (eds) 1-2 and phytoalexin deficient (pad) 4-1 suppressed acd6-1-conferred small size, cell death, and defense phenotypes, a combination of these two mutations did not incur additive suppression. This suggests that EDS1 and PAD4 act in the same signaling pathway. To further evaluate genetic interactions among SA regulators, we constructed 10 pairwise crosses in the acd6-1 background among mutants defective in: SA INDUCTION-DEFICIENT 2 for SA biosynthesis; AGD2-LIKE DEFENSE 1, EDS5, and PAD4 for SA accumulation; and NONEXPRESSOR OF PR GENES 1 for SA signaling. Systematic analysis of the triple mutants based on their suppression of acd6-1-conferred phenotypes revealed complex and interactive genetic relationships among the tested SA genes. Our results suggest a more comprehensive view of the gene networks governing SA function and provide a framework for further interrogation of the important roles of SA and possibly other signaling molecules in regulating plant disease resistance. IN response to pathogen infection, plants can activate different layers of defense responses and undergo global gene expression reprogramming (Maleck et al. 2000;Tao et al. 2003;Katagiri 2004). A major challenge of the postgenomic era is to identify genes that control plant innate immunity and to elucidate how they are organized into networks to orchestrate host defense responses.One key hub in plant defense signaling networks is centered on the small phenolic molecule salicylic acid (SA). SA is important for basal defense, resistance proteinmediated defense, and systemic acquired resistance (HammondKosack and Jones 1996;Ryals et al. 1996;Tsuda et al. 2008). The SA hub of Arabidopsis includes many genes, which can be further grouped into three types on the basis of how they affect SA-mediated defense (Lu 2009). Type I SA genes encode enzymes that are directly involved in SA biosynthesis. One example is SA INDUCTION-DEFICIENT 2/ENHANCED DISEASE SUSCEPTIBILITY 16 (SID2/EDS16), which encodes isochorismate synthase contributing to bulk SA biosynthesis (Wildermuth et al. 2001). Type II SA genes encode proteins that do not act directly as SA biosynthetic enzymes. Mutations in these genes lead to partially compromised SA accumulation and enhanced disease susceptibility to pathogen infection, which can be rescued by exogenous SA treatment. The precise mechanism of action for each type II SA gene, however, still remains to be resolved. Example...

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Section: Discussionmentioning

confidence: 99%

Genetic Dissection of Salicylic Acid-Mediated Defense Signaling Networks in Arabidopsis

Ng¹,

Seabolt²,

Zhang

et al. 2011

Genetics

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“…Finally, a novel aminotransferase known as AGD2 seems to be involved in the synthesis of an essential amino acid-derived molecule affecting development and defense (42). If confirmed by future work, the role of redox, currently linked to disease resistance by Cf-9 (via CITRX) (43) and NPR1 (via an unknown mediator) (44), would be extended to pathogenesis and development by AGD2 (via Trx).…”

Section: Identification Of Members Of the Ferredoxin͞trx System And Smentioning

confidence: 99%

A complete ferredoxin/thioredoxin system regulates fundamental processes in amyloplasts

Balmer

Vensel

Cai

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

160

137

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A growing number of processes throughout biology are regulated by redox via thiol-disulfide exchange. This mechanism is particularly widespread in plants, where almost 200 proteins have been linked to thioredoxin (Trx), a widely distributed small regulatory disulfide protein. The current study extends regulation by Trx to amyloplasts, organelles prevalent in heterotrophic plant tissues that, among other biosynthetic activities, catalyze the synthesis and storage of copious amounts of starch. Using proteomics and immunological methods, we identified the components of the ferredoxin͞Trx system (ferredoxin, ferredoxin-Trx reductase, and Trx), originally described for chloroplasts, in amyloplasts isolated from wheat starchy endosperm. Ferredoxin is reduced not by light, as in chloroplasts, but by metabolically generated NADPH via ferredoxin-NADP reductase. However, once reduced, ferredoxin appears to act as established for chloroplasts, i.e., via ferredoxinTrx reductase and a Trx (m-type). A proteomics approach in combination with affinity chromatography and a fluorescent thiol probe led to the identification of 42 potential Trx target proteins, 13 not previously recognized, including a major membrane transporter (Brittle-1 or ADP-glucose transporter). The proteins function in a range of processes in addition to starch metabolism: biosynthesis of lipids, amino acids, and nucleotides; protein folding; and several miscellaneous reactions. The results suggest a mechanism whereby light is initially recognized as a thiol signal in chloroplasts, then as a sugar during transit to the sink, where it is converted again to a thiol signal. In this way, amyloplast reactions in the grain can be coordinated with photosynthesis taking place in leaves.redox regulation ͉ target proteins ͉ ferredoxin-thioredoxin reductase O ur understanding of the function of the regulatory disulfide protein thioredoxin (Trx) has increased dramatically in the past few years, with the advent of new methodologies. Recent approaches make it possible to identify proteins linked to Trx by combining proteomics with affinity chromatography (1) or thiol probes (2-4). These capabilities have defined an extended role of Trx in chloroplasts (1, 5) and helped elucidate its function in other plant systems: mitochondria (6), seeds (2,3,7,8), and seedlings (4, 9). Currently almost 200 proteins appear to be linked to Trx in plants (10). One major organelle that has been neglected, however, is the amyloplast, a plastid of heterotrophic tissues that performs a wide range of biosynthetic reactions, including the synthesis and storage of abundant quantities of starch.To help fill this gap, we have applied proteomic and immunological approaches to investigate the occurrence and function of Trx in amyloplasts. We now report evidence that amyloplasts isolated from wheat starchy endosperm resemble chloroplasts in containing a complete ferredoxin͞Trx system composed of ferredoxin, ferredoxin-Trx reductase (FTR), and Trx (m-type). Application of affinity chromatography and fl...

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“…6A), a phenotype that we previously found strongly correlates with 258 hypersusceptibility (e.g. see (Lu et al, 2003;Song et al, 2004;Lee et al, 2007)). 259…”

Section: Sa and Pr1 Levels In Response To Uv-c Treatment And Bacteriamentioning

confidence: 99%

“…under some conditions, such as nitric oxide with reduced SA production, generated by altered expression/mutation of genes that impact 339 SA biosynthesis, exhibit enhanced susceptibility to virulent and avirulent pathogens, 340 similar to the phenotype of phb3-3 (Delaney et al, 1994;Nawrath and Métraux, 1999;341 Dewdney et al, 2000;Lu et al, 2003;Song et al, 2004;Lee et al, 2007). 342…”

Section: Phb3 Regulates Ics1 Protein Levels 292mentioning

confidence: 99%

PROHIBITIN3 Forms Complexes with ISOCHORISMATE SYNTHASE1 to Regulate Stress-Induced Salicylic Acid Biosynthesis in Arabidopsis

et al. 2018

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Divergent Roles in Arabidopsis thaliana Development and Defense of Two Homologous Genes, ABERRANT GROWTH AND DEATH2 and AGD2-LIKE DEFENSE RESPONSE PROTEIN1, Encoding Novel Aminotransferases

Cited by 125 publications

References 70 publications

Genetic Dissection of Salicylic Acid-Mediated Defense Signaling Networks in Arabidopsis

Genetic Dissection of Salicylic Acid-Mediated Defense Signaling Networks in Arabidopsis

A complete ferredoxin/thioredoxin system regulates fundamental processes in amyloplasts

PROHIBITIN3 Forms Complexes with ISOCHORISMATE SYNTHASE1 to Regulate Stress-Induced Salicylic Acid Biosynthesis in Arabidopsis

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