Transcriptome analysis of a bacterially induced basal and hypersensitive response of Medicago truncatula

Photorespiration represents one of the major highways of primary plant metabolism and is the most prominent example of metabolic cell organelle integration, since the pathway requires the concerted action of plastidial, peroxisomal, mitochondrial and cytosolic enzymes and organellar transport proteins. Oxygenation of ribulose-1,5-bisphosphate by Rubisco leads to the formation of large amounts of 2-phosphoglycolate, which are recycled to 3-phosphoglycerate by the photorespiratory C2 cycle, concomitant with stoichiometric production rates of H2 O2 in peroxisomes. Apart from its significance for agricultural productivity, a secondary function of photorespiration in pathogen defence has emerged only recently. Here, we summarise literature data supporting the crosstalk between photorespiration and pathogen defence and perform a meta-expression analysis of photorespiratory genes during pathogen attack. Moreover, we screened Arabidopsis proteins newly predicted using machine learning methods to be targeted to peroxisomes, the central H2 O2 -producing organelle of photorespiration, for homologues of known pathogen defence proteins and analysed their expression during pathogen infection. The analyses further support the idea that photorespiration and non-photorespiratory peroxisomal metabolism play multi-faceted roles in pathogen defence beyond metabolism of reactive oxygen species.

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“…; Bozso et al . ). Little is known about the corresponding reactions of the photorespiratory gene cluster.…”

Section: A Meta‐analysis Of Photorespiratory Gene Expression During Dmentioning

confidence: 97%

The emerging role of photorespiration and non‐photorespiratory peroxisomal metabolism in pathogen defence

et al. 2013

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“…Gene up-regulated in wild type and mutant nodules ([19] [20], this study) as well as M. truncatula plants treated by yeast elicitor [68] or challenged with the bacterial pathogen Pseudomonas syringae [103].…”

Section: Supporting Informationmentioning

confidence: 99%

Transcription Reprogramming during Root Nodule Development in Medicago truncatula

et al. 2011

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Many genes which are associated with root nodule development and activity in the model legume Medicago truncatula have been described. However information on precise stages of activation of these genes and their corresponding transcriptional regulators is often lacking. Whether these regulators are shared with other plant developmental programs also remains an open question. Here detailed microarray analyses have been used to study the transcriptome of root nodules induced by either wild type or mutant strains of Sinorhizobium meliloti. In this way we have defined eight major activation patterns in nodules and identified associated potential regulatory genes. We have shown that transcription reprogramming during consecutive stages of nodule differentiation occurs in four major phases, respectively associated with (i) early signalling events and/or bacterial infection; plant cell differentiation that is either (ii) independent or (iii) dependent on bacteroid differentiation; (iv) nitrogen fixation. Differential expression of several genes involved in cytokinin biosynthesis was observed in early symbiotic nodule zones, suggesting that cytokinin levels are actively controlled in this region. Taking advantage of databases recently developed for M. truncatula, we identified a small subset of gene expression regulators that were exclusively or predominantly expressed in nodules, whereas most other regulators were also activated under other conditions, and notably in response to abiotic or biotic stresses. We found evidence suggesting the activation of the jasmonate pathway in both wild type and mutant nodules, thus raising questions about the role of jasmonate during nodule development. Finally, quantitative RT-PCR was used to analyse the expression of a series of nodule regulator and marker genes at early symbiotic stages in roots and allowed us to distinguish several early stages of gene expression activation or repression.

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“…The up‐regulation of specific PR10 genes was also observed in the resistance response of M. truncatula to Colletotrichum trifolii (Torregrosa et al ., 2004). Genes from PR10, PR10.1 and PR10.2 families were strongly up‐regulated in both compatible and incompatible interactions with the bacterial pathogen Pseudomonas syringae (Bozsó et al ., 2009). PR10‐like proteins have been observed to accumulate in M. truncatula roots after inoculation with the oomycete pathogen Aphanomyces euteiches , but the increased abundance of several PR10 proteins was specifically associated with a susceptible reaction (Colditz et al ., 2005).…”

Section: Introductionmentioning

confidence: 99%

Expression of coordinately regulated defence response genes and analysis of their role in disease resistance in Medicago truncatula

Samac

Peñuela

Schnurr³

et al. 2011

Molecular Plant Pathology

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Microarray technology was used to identify the genes associated with disease defence responses in the model legume Medicago truncatula. Transcript profiles from M. truncatula cv. Jemalong genotype A17 leaves inoculated with Colletotrichum trifolii and Erysiphe pisi and roots infected with Phytophthora medicaginis were compared to identify the genes expressed in response to all three pathogens and genes unique to an interaction. The A17 genotype is resistant to C. trifolii and E. pisi, exhibiting a hypersensitive response after inoculation, and is moderately susceptible to P. medicaginis. Among the most strongly up-regulated genes in all three interactions were those encoding a hevein-like protein, thaumatin-like protein (TLP) and members of the pathogenesis response (PR)10 family. Transcripts of genes for enzymes in the phenylpropanoid pathway leading to the production of isoflavonoid phytoalexins increased dramatically in response to inoculation with the foliar pathogens. In P. medicaginis-inoculated roots, transcripts of genes in the phenylpropanoid pathway peaked at 5 days post-inoculation, when symptoms became visible. Transcript accumulation of three PR10 family members, a TLP and chalcone synthase (CHS) was assessed in M. truncatula genotype R108 plants. The R108 plants are resistant to C. trifolii and moderately susceptible to E. pisi and P. medicaginis. Transcript accumulation paralleled the stages of pathogen development. To evaluate the role of a TLP, a PR10 family member and CHS in disease resistance, transgenic R108 plants containing interfering RNA (RNAi) constructs were produced. Reduced expression of PR10 and TLP had no effect on the disease phenotype, whereas reduced expression of CHS resulted in increased susceptibility to necrotrophic pathogens.

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Transcriptome analysis of a bacterially induced basal and hypersensitive response of Medicago truncatula

Cited by 19 publications

References 82 publications

The emerging role of photorespiration and non‐photorespiratory peroxisomal metabolism in pathogen defence

The emerging role of photorespiration and non‐photorespiratory peroxisomal metabolism in pathogen defence

Transcription Reprogramming during Root Nodule Development in Medicago truncatula

Expression of coordinately regulated defence response genes and analysis of their role in disease resistance in Medicago truncatula

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