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Huanglongbing disease affects the Rutaceae family and is associated with three phloem-limited bacterium species: Candidatus Liberibacter asiaticus, africanus and americanus. These species are considered quarantine pathogens in the world, and pose major risks for citrus production and industry. Due to the low titer and the uneven distribution of the bacteria within its host plant, conventional PCR detection protocols can lead to false negative results, especially for early detection. Herein, three real-time PCR diagnostic methods recommended by the EPPO and FAO for asiaticus and africanus species detection were evaluated for their performance and compared with a conventional duplex PCR. Assessments were done as part of an international cooperative project under the EUPHRESCO guidance. Intra-laboratory assessment of the analytical specificity and analytical sensitivity was performed on 33 target or non-target DNA samples and seven target DNA samples were used to determine the sensitivity. Thereafter, repeatability, reproducibility, and concordance odds ratio were assessed on 20 target or non-target DNA samples through a collaborative test performance study organized among eight international laboratories. Results showed that the Li protocol proved to be the best method for asiaticus and africanus species detection, along with the conventional duplex PCR; whereas the Morgan protocol showed high performance only for asiaticus species. Interlaboratory reproducibility was high, suggesting that these real-time PCR methods can be readily transferred to diagnostic laboratories.

The battle between humans and plant pests is as old as agriculture, but the movement of pests as a consequence of human activities has been exacerbated only recently. International research collaboration is increasingly important to tackle pests causing serious damage to economies.

The Euphresco (European phytosanitary research coordination) network is an ERA-NET initially funded by the 6 th and 7 th EU Framework Programmes as an initiative to enhance public-public partnership in the statutory plant health sector. An inventory was organised in 2015 to collect information on the national phytosanitary research programmes and their research projects in the EPPO region. The information collected through the Euphresco inventory provides precious insights into national research activities to avoid programme duplication and to increase programme depth among the phytosanitary research funders of the EPPO region and beyond.

UMR BFP - Equipe Virologie; International audience; High-throughput sequencing (HTS) technologies have revolutionized plant pest research and are now raising interest for plant pest diagnostics, with plant virus diagnostics at the forefront of development. However, the application of HTS in plant pest diagnostics raisesimportant challenges that plant health regulators will have to address. Adapted infrastructures, technical guidelines and training are pivotal for further use and adoption of the HTS technologies in the phytosanitary framework.

A clone, designated L20h-Ts3, was selected by immunoscreening of cDNA libraries of Trichinella spiralis worms collected 14h, 20h and 48h post-infection (p.i.) from mice intestines. L20h-Ts3 encodes the full-length of a conserved hypothetical protein of 13.1kDa involving putative interaction with the immune system. PCR analysis showed that L20h-Ts3 mRNA is constitutively expressed throughout T. spiralis life cycle and not restricted to intestinal stages. The L20h-Ts3 fusion protein was obtained in an Escherichia coli expression system and purified by Ni-affinity chromatography before inoculation into mice in order to produce polyclonal antibodies. Then, immunohistochemical study and Western blot analysis revealed its presence within the stichosome of T. spiralis and in excretory/secretory products strengthening a putative fundamental role for the parasite's survival such as host tissue invasion or modification of the host muscular cell phenotype. L20h-Ts3 fusion protein was recognized in Western blot as soon as 15–20 days p.i. by sera from pigs experimentally infected with 20,000 muscle larvae (ML) of T. spiralis. Thus, an indirect L20h-Ts3 ELISA was designed and evaluated using sera from experimentally infected pigs by comparison with the only ELISA currently available for trichinellosis purposes. A gain of precocity from 7 up to 14 days and detection up to 25 weeks p.i. was possible with the L20h-Ts3 ELISA offering a large window for trichinellosis detection. The L20h-Ts3 ELISA was less effective in the case of low infections in pigs. Nevertheless, these results show that the L20h-Ts3 ELISA has a real interest due to its precocity and stability of detection in time. The association of the L20h-Ts3 fusion protein with other antigenic proteins identified previously could appreciably improve the serological test and facilitate its standardization.

Protein splicing is a post-translational modification in which an intein domain excises itself out of a host protein. Here, we investigate how the steps in the splicing process are coordinated so as to maximize the production of the final splice products and minimize the generation of undesired cleavage products. Our approach has been to prepare a branched intermediate (and analogs thereof) of the Mycobacterium xenopi DNA gyrase A (Mxe GyrA) intein using protein semisynthesis. Kinetic analysis of these molecules indicates that the high fidelity of this protein-splicing reaction results from the penultimate step in the process (intein-succinimide formation) being rate-limiting. NMR experiments indicate that formation of the branched intermediate affects the local structure around the amide bond that is cleaved during succinimide formation. We propose that this structural change reflects a reorganization of the catalytic apparatus to accelerate succinimide formation at the C-terminal splice junction.

The European Phytosanitary Research and Coordination network (Euphresco, www.euphresco.net) is a network of organisations which were initiated as EU funded ERA-NET projects in 2006 and 2010. The goal of the network is to strengthen the networking of research activities carried out at national or regional level and the mutual opening of research programmes. In 2014, having received EU funding twice, Euphresco members decided to continue to work together as a long-term and self-sustaining network. The coordination of Euphresco is now hosted within the European and Mediterranean Plant Protection Organization (EPPO), and in addition to consolidating the network and its procedures, it is also preparing the ground for future developments. Euphresco: une opportunite pour la coordination et le financement de la recherche phytosanitaire dans la region OEPP et d'autres pays Le reseau de recherche et de coordination phytosanitaire europeen (Euphresco, www.euphresco.net) est un reseau d'organisations qui a ete lance sous forme de projets ERA-NET finances par l'UE en 2006 et 2010. L'objectif du reseau est de renforcer la mise en reseau des activites de recherche menees au niveau national ou regional, et l'ouverture mutuelle des programmes de recherche. En 2014, ayant recu a deux reprises un financement de l'UE, les membres d'Euphresco ont decide de continuer a travailler ensemble dans le cadre d'un reseau a long terme et autonome. Le secretariat de coordination d'Euphresco est maintenant heberge au sein de l'Organisation Europeenne et Mediterraneenne pour la Protection des Plantes (OEPP). Outre la consolidation du reseau et de ses procedures, il prepare aussi le terrain pour de futurs developpements. Euphresco: вoзмoжнocть кoopдинaции и финaнcиpoвaния фитocaнитapныx иccлeдoвaний в peгиoнe EOКЗP и зa eё пpeдeлaми

Cryptochromes are blue-light photoreceptors sharing sequence similarity to photolyases, a class of flavoenzymes catalyzing repair of UV-damaged DNA via electron transfer mechanisms. Despite significant amino acid sequence similarity in both catalytic and cofactor-binding domains, cryptochromes lack DNA repair functions associated with photolyases, and the molecular mechanism involved in cryptochrome signaling remains obscure. Here, we report a novel ATP binding and autophosphorylation activity associated with Arabidopsis cry1 protein purified from a baculovirus expression system. Autophosphorylation occurs on serine residue(s) and is absent in preparations of cryptochrome depleted in flavin and/or misfolded. Autophosphorylation is stimulated by light in vitro and oxidizing agents that act as flavin antagonists prevent this stimulation. Human cry1 expressed in baculovirus likewise shows ATP binding and autophosphorylation activity, suggesting this novel enzymatic activity may be important to the mechanism of action of both plant and animal cryptochromes.

Expressed protein ligation (EPL) is a protein semisynthesis technique that allows the site-specific introduction of unnatural amino acids and biophysical probes into proteins. In the present study, we illustrate the utility of the approach through the generation of two semisynthetic proteins bearing spectroscopic probes. Dihydrofolate reductase containing a single (13)C probe in an active site loop was generated through the ligation of a synthetic peptide-alpha-thioester to a recombinantly generated fragment containing an N-terminal Cys. Similarly, c-Crk-II was assembled by the sequential ligation of three recombinant polypeptide building blocks, allowing the incorporation of (15)N isotopes in the central domain of the protein. These examples showcase the scope of the protein ligation strategy for selective introduction of isotopic labels into proteins, and the protocols described will be of value to those interested in using EPL on other systems.

Cryptochromes are blue light-activated photoreceptors found in multiple organisms with significant similarity to photolyases, a class of light-dependent DNA repair enzymes. Unlike photolyases, cryptochromes do not repair DNA and instead mediate blue light-dependent developmental, growth, and/or circadian responses by an as yet unknown mechanism of action. It has recently been shown that Arabidopsis cryptochrome-1 retains photolyase-like photoreduction of its flavin cofactor FAD by intraprotein electron transfer from tryptophan and tyrosine residues. Here we demonstrate that substitution of two conserved tryptophans that are constituents of the flavin-reducing electron transfer chain in Escherichia coli photolyase impairs light-induced electron transfer in the Arabidopsis cryptochrome-1 photoreceptor in vitro. Furthermore, we show that these substitutions result in marked reduction of light-activated autophosphorylation of cryptochrome-1 in vitro and of its photoreceptor function in vivo, consistent with biological relevance of the electron transfer reaction. These data support the possibility that light-induced flavin reduction via the tryptophan chain is the primary step in the signaling pathway of plant cryptochrome.

Cryptochromes are blue-light photoreceptors involved in a variety of signaling pathways in both plants and animals, including blue light-dependent growth, development and entrainment of circadian rhythms. They are characterized by their significant amino acid sequence similarity to photolyases, particularly in the N-terminal chromophore binding and catalytic domain ([Ahmad 2003]). Many of the amino acids known to function inflavin binding are conserved in the cryp- tochromes, which apparently bind to the same chromophores as do photolyases ([Lin et al 1995]). In addition, most cryptochromes have poorly conserved C- terminal extensions that are thought to interact with downstream cellular sig- naling intermediates such as transcription factors. It has been proposed that a light-induced intramolecular redox reaction may trigger conformational changes in the protein ([Yang et al 2000]). In particular, it has been proposed that the C- terminal domain may in this way become accessible to molecular targets such as COP1, which are downstream elements in the signaling pathway of cryp- tochromes ([Yang et al 2001])

Cryptochromes are blue-light photoreceptors sharing sequence similarity to photolyases, a class of flavoenzymes catalyzing repair of UV-damaged DNA via electron transfer mechanisms. Despite significant amino acid sequence similarity in both catalytic and cofactor-binding domains, cryptochromes lack DNA repair functions associated with photolyases, and the molecular mechanism involved in cryptochrome signaling remains obscure. Here, we report a novel ATP binding and autophosphorylation activity associated with Arabidopsis cry1 protein purified from a baculovirus expression system. Autophosphorylation occurs on serine residue(s) and is absent in preparations of cryptochrome depleted in flavin and/or misfolded. Autophosphorylation is stimulated by light in vitro and oxidizing agents that act as flavin antagonists prevent this stimulation. Human cry1 expressed in baculovirus likewise shows ATP binding and autophosphorylation activity, suggesting this novel enzymatic activity may be important to the mechanism of action of both plant and animal cryptochromes.

Cryptochrome blue-light photoreceptors are found in both plants and animals and have been implicated in numerous developmental and circadian signaling pathways. Nevertheless, no action spectrum for a physiological response shown to be entirely under the control of cryptochrome has been reported. In this work, an action spectrum was determined in vivo for a cryptochrome-mediated high-irradiance response, the blue-light-dependent inhibition of hypocotyl elongation in Arabidopsis. Comparison of growth of wild-type,cry1cry2 cryptochrome-deficient double mutants, and cryptochrome-overexpressing seedlings demonstrated that responsivity to monochromatic light sources within the range of 390 to 530 nm results from the activity of cryptochrome with no other photoreceptor having a significant primary role at the fluence range tested. In both green- and norflurazon-treated (chlorophyll-deficient) seedlings, cryptochrome activity is fairly uniform throughout its range of maximal response (390–480 nm), with no sharply defined peak at 450 nm; however, activity at longer wavelengths was disproportionately enhanced in CRY1-overexpressing seedlings as compared with wild type. The action spectrum does not correlate well with the absorption spectra either of purified recombinant cryptochrome photoreceptor or to that of a second class of blue-light photoreceptor, phototropin (PHOT1 and PHOT2). Photoreceptor concentration as determined by western-blot analysis showed a greater stability of CRY2 protein under the monochromatic light conditions used in this study as compared with broad band blue light, suggesting a complex mechanism of photoreceptor activation. The possible role of additional photoreceptors (in particular phytochrome A) in cryptochrome responses is discussed.

Cryptochromes are flavoproteins implicated in multiple blue light-dependent signaling pathways regulating, for example, photomorphogenesis in plants or circadian clocks in animals. Using transient absorption spectroscopy, it is demonstrated that the primary light reactions in isolated Arabidopsis thaliana cryptochrome-1 involve intraprotein electron transfer from tryptophan and tyrosine residues to the excited flavin adenine dinucleotide cofactor.