Identification and characterization of the Non-race specific Disease Resistance 1 (NDR1) orthologous protein in coffee

<p>Abstract</p> <p>Background</p> <p>Leaf rust, which is caused by the fungus <it>Hemileia vastatrix </it>(Pucciniales), is a devastating disease that affects coffee plants (<it>Coffea arabica </it>L.). Disadvantages that are associated with currently developed phytoprotection approaches have recently led to the search for alternative strategies. These include genetic manipulations that constitutively activate disease resistance signaling pathways. However, molecular actors of such pathways still remain unknown in <it>C. arabica</it>. In this study, we have isolated and characterized the coffee <it>NDR1 </it>gene, whose <it>Arabidopsis </it>ortholog is a well-known master regulator of the hypersensitive response that is dependent on coiled-coil type R-proteins.</p> <p>Results</p> <p>Two highly homologous cDNAs coding for putative NDR1 proteins were identified and cloned from leaves of coffee plants. One of the candidate coding sequences was then expressed in the <it>Arabidopsis </it>knock-out null mutant <it>ndr1-1</it>. Upon a challenge with a specific strain of the bacterium <it>Pseudomonas syringae </it>(DC3000::<it>AvrRpt2</it>), analysis of both macroscopic symptoms and <it>in planta </it>microbial growth showed that the coffee cDNA was able to restore the resistance phenotype in the mutant genetic background. Thus, the cDNA was dubbed <it>CaNDR1a </it>(standing for <it>Coffea arabica Non-race specific Disease Resistance 1a</it>). Finally, biochemical and microscopy data were obtained that strongly suggest the mechanistic conservation of the <it>NDR1</it>-driven function within coffee and <it>Arabidopsis </it>plants. Using a transient expression system, it was indeed shown that the CaNDR1a protein, like its <it>Arabidopsis </it>counterpart, is localized to the plasma membrane, where it is possibly tethered by means of a GPI anchor.</p> <p>Conclusions</p> <p>Our data provide molecular and genetic evidence for the identification of a novel functional <it>NDR1 </it>homolog in plants. As a key regulator initiating hypersensitive signalling pathways, <it>CaNDR1 </it>gene(s) might be target(s) of choice for manipulating the coffee innate immune system and achieving broad spectrum resistance to pathogens. Given the potential conservation of <it>NDR1</it>-dependent defense mechanisms between <it>Arabidopsis </it>and coffee plants, our work also suggests new ways to isolate the as-yet-unidentified <it>R</it>-gene(s) responsible for resistance to <it>H. vastatrix</it>.</p

Identification and characterization of the Non- race specific Disease Resistance 1 (NDR1) orthologous protein in coffee

Abstract Background: Leaf rust, which is caused by the fungus Hemileia vastatrix (Pucciniales), is a devastating disease that affects coffee plants (Coffea arabica L.). Disadvantages that are associated with currently developed phytoprotection approaches have recently led to the search for alternative strategies. These include genetic manipulations that constitutively activate disease resistance signaling pathways. However, molecular actors of such pathways still remain unknown in C. arabica. In this study, we have isolated and characterized the coffee NDR1 gene, whose Arabidopsis ortholog is a well-known master regulator of the hypersensitive response that is dependent on coiledcoil type R-proteins

How lipids contribute to autophagosome biogenesis, a critical process in plant responses to stresses

Throughout their life cycle, plants face a tremendous number of environmental and developmental stresses. To respond to these different constraints, they have developed a set of refined intracellular systems including autophagy. This pathway, highly conserved among eukaryotes, is induced by a wide range of biotic and abiotic stresses upon which it mediates the degradation and recycling of cytoplasmic material. Central to autophagy is the formation of highly specialized double membrane vesicles called autophagosomes which select, engulf, and traffic cargo to the lytic vacuole for degradation. The biogenesis of these structures requires a series of membrane remodeling events during which both the quantity and quality of lipids are critical to sustain autophagy activity. This review highlights our knowledge, and raises current questions, regarding the mechanism of autophagy, and its induction and regulation upon environmental stresses with a particular focus on the fundamental contribution of lipids. How autophagy regulates metabolism and the recycling of resources, including lipids, to promote plant acclimation and resistance to stresses is further discussed

How very-long-chain fatty acids could signal stressful conditions in plants?

Although encountered in minor amounts in plant cells, very-long-chain fatty acids exert crucial functions in developmental processes. When their levels is perturbed by means of genetic approaches, marked phenotypic consequences that range from severe growth retardation to embryo lethality was indeed reported. More recently, a growing body of findings has also accumulated that points to a potential role for these lipids as signals in governing both biotic and abiotic stress outcomes. In the present work, we discuss the latter theory and explore the ins and outs of very-long-chain fatty acid-based signaling in response to stress, with an attempt to reconcile two supposedly antagonistic parameters: the insoluble nature of fatty acids and their signaling function. To explain this apparent dilemma, we provide new interpretations of pre-existing data based on the fact that sphingolipids are the main reservoir of very-long-chain fatty acids in leaves. Thus, three non-exclusive, molecular scenarii that involves these lipids as membrane-embedded and free entities are proposed

Devil inside : does plant programmed cell death involve the endomembrane system ?

Eukaryotic cells have to constantly cope with environmental cues and integrate developmental signals. Cell survival or death is the only possible outcome. In the field of animal biology, tremendous efforts have been put into the understanding of mechanisms underlying cell fate decision. Distinct organelles have been proven to sense a broad range of stimuli and, if necessary, engage cell death signalling pathway(s). Over the years, forward and reverse genetic screens have uncovered numerous regulators of programmed cell death (PCD) in plants. However, to date, molecular networks are far from being deciphered and, apart from the autophagic compartment, no organelles have been assigned a clear role in the regulation of cellular suicide. The endomembrane system (ES) seems, nevertheless, to harbour a significant number of cell death mediators. In this review, the involvement of this system in the control of plant PCD is discussed in-depth, as well as compared and contrasted with what is known in animal and yeast systems

Petite hydraulique et débit réservé, colloque petite hydraulique octobre 1985

National audienceLa mise en place de micro-centrales et la substitution d'un débit artificiel réduit, à un débit naturel s'accompagne de répercussions sur la rivière dont la moindre n'est pas la diminution de la surface mouillée. Diminution de la vitesse, abaissement du tirant d'eau, augmentation des amplitudes de variation de la température et de l'oxygène dissous, envahissement par la végétation, concentration de la pollution ; ces modifications entraînent une altération fonctionnelle de la biocénose et un appauvrissement halieutique. De nombreuses méthodes employées outre-atlantique visent à établir une valeur-seuil du débit au delà de laquelle les modifications du milieu aquatique sont suffisantes pour provoquer un dérèglement fonctionnel de la biocénose. Le principe de ces méthodes est repris par le Cemagref pour développer un outil commode à l'usage des aménageurs et des gestionnaires de la pêche, qui permettrait d'établir un chiffre de débit admissible fondé sur des critères géomorphologiques et biologiques

Petite hydraulique et débit réservé, colloque petite hydraulique octobre 1985

National audienceLa mise en place de micro-centrales et la substitution d'un débit artificiel réduit, à un débit naturel s'accompagne de répercussions sur la rivière dont la moindre n'est pas la diminution de la surface mouillée. Diminution de la vitesse, abaissement du tirant d'eau, augmentation des amplitudes de variation de la température et de l'oxygène dissous, envahissement par la végétation, concentration de la pollution ; ces modifications entraînent une altération fonctionnelle de la biocénose et un appauvrissement halieutique. De nombreuses méthodes employées outre-atlantique visent à établir une valeur-seuil du débit au delà de laquelle les modifications du milieu aquatique sont suffisantes pour provoquer un dérèglement fonctionnel de la biocénose. Le principe de ces méthodes est repris par le Cemagref pour développer un outil commode à l'usage des aménageurs et des gestionnaires de la pêche, qui permettrait d'établir un chiffre de débit admissible fondé sur des critères géomorphologiques et biologiques

Characterization of glycosyl inositol phosphoryl ceramides from plants and fungi by mass spectrometry

SPE IPMInternational audienceAlthough glycosyl inositol phosphoryl ceramides (GIPCs) represent the most abundant class of sphingolipids in plants, they still remain poorly characterized in terms of structure and biodiversity. More than 50 years after their discovery, little is known about their subcellular distribution and their exact roles in membrane structure and biological functions. This review is focused on extraction and characterization methods of GIPCs occurring in plants and fungi. Global methods for characterizing ceramide moieties of GIPCs revealed the structures of long-chain bases (LCBs) and fatty acids (FAs): LCBs are dominated by tri-hydroxylated molecules such as monounsaturated and saturated phytosphingosine (t18:1 and t18:0, respectively) in plants and mainly phytosphingosine (t18:0 and t20:0) in fungi; FA are generally 14-26 carbon atoms long in plants and 16-26 carbon atoms long in fungi, these chains being often hydroxylated in position 2. Mass spectrometry plays a pivotal role in the assessment of GIPC diversity and the characterization of their structures. Indeed, it allowed to determine that the core structure of GIPC polar heads in plants is Hex(R1)-HexA-IPC, with R1 being a hydroxyl, an amine, or a N-acetylamine group, whereas the core structure in fungi is Man-IPC. Notably, information gained from tandem mass spectrometry spectra was most useful to describe the huge variety of structures encountered in plants and fungi and reveal GIPCs with yet uncharacterized polar head structures, such as hexose-inositol phosphoceramide in Chondracanthus acicularis and (hexuronic acid)(4)-inositol phosphoceramide and hexose-(hexuronic acid)(3)-inositol phosphoceramide in Ulva lactuca

PUX10 is a CDC48A Adaptor Protein that Regulates the Extraction of Ubiquitinated Oleosins from Seed Lipid Droplets in Arabidopsis

International audiencePost-germinative mobilization of neutral lipids stored in seed lipid droplets (LDs) is preceded by the degradation of oleosins, the major structural LD proteins that stabilize LDs in dry seeds. We previously showed that Arabidopsis thaliana oleosins are marked for degradation by ubiquitination, and extracted from LDs before proteolysis. However, the mechanisms underlying the dislocation of these LD-anchored proteins from the LD monolayer are yet unknown. Here, we report that PUX10, a member of the plant UBX-domain containing (PUX) protein family, is an integral LD protein that associates with a subpopulation of LDs during seed germination. In pux10 mutant seedlings, PUX10 deficiency impaired the degradation of ubiquitinated oleosins, and prevented the extraction of ubiquitinated oleosins from LDs. We also showed that PUX10 interacts with ubiquitin and CDC48A, the AAA ATPase Cell Division Cycle 48, through its UBA and UBX domains, respectively. Collectively, these results strongly suggest that PUX10 is an adaptor recruiting CDC48A to ubiquitinated oleosins, thus facilitating the dislocation of oleosins from LDs by the segregase activity of CDC48A. We propose that PUX10 and CDC48A are core components of a LD-associated degradation machinery, which we named the LD-associated degradation (LDAD) system. Importantly, PUX10 is also the first determinant of a LD subpopulation described in plants, suggesting functional differentiation of LDs in Arabidopsis seedlings

UTILISATION DE L'ACIDE 4-PHÉNYLBUTYRIQUE ET/OU DE L'ACIDE 3-PHÉNYLBUTYRIQUE ET/OU DE L'ACIDE 2-PHÉNYLBUTYRIQUE POUR LA PRÉVENTION ET LE TRAITEMENT DES MALADIES CRYPTOGAMIQUES

The present invention relates to the use of 2-phenylbutyric acid or 3-phenylbutyric acid or 4-phenylbutyric acid, or a salt thereof, or a combination thereof, to combat cryptogamic diseases which are caused by fungi or oomycetes. The present invention also relates to the use of these compounds and these combinations as fungicidal or fungistatic agents in preventing or curing cryptogamic diseases.La présente invention concerne l'utilisation de l'acide 2-phénylbutyrique, ou de l'acide 3-phénylbutyrique, ou de l'acide 4-phénylbutyrique, ou de l'un de leurs sels, ou de l'une de leurs combinaisons, pour lutter contre les maladies cryptogamiques causées par les champignons et les oomycètes. La présente invention porte également sur l'utilisation de ces composés et de ces combinaisons comme agents fongicides ou fongistatiques pour la prévention ou le traitement curatif de maladies cryptogamiques