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Despite the pivotal role of jasmonic acid in the outcome of plant-microorganism interactions, JA-signaling components in roots of perennial trees like western balsam poplar (Populus trichocarpa) are poorly characterized. Here we decipher the poplar-root JA-perception complex centered on PtJAZ6, a co-repressor of JA-signaling targeted by the effector protein MiSSP7 from the ectomycorrhizal basidiomycete Laccaria bicolor during symbiotic development. Through protein–protein interaction studies in yeast we determined the poplar root proteins interacting with PtJAZ6. Moreover, we assessed via yeast triple-hybrid how the mutualistic effector MiSSP7 reshapes the association between PtJAZ6 and its partner proteins. In the absence of the symbiotic effector, PtJAZ6 interacts with the transcription factors PtMYC2s and PtJAM1.1. In addition, PtJAZ6 interacts with it-self and with other Populus JAZ proteins. Finally, MiSSP7 strengthens the binding of PtJAZ6 to PtMYC2.1 and antagonizes PtJAZ6 homo-/heterodimerization. We conclude that a symbiotic effector secreted by a mutualistic fungus may promote the symbiotic interaction through altered dynamics of a JA-signaling-associated protein–protein interaction network, maintaining the repression of PtMYC2.1-regulated genes.

International audience; Semiconductor quantum dots (QDs) embedded into polymer microbeads are known to be very attractive emitters for spectral multiplexing and colour encoding. Their luminescence lifetimes or decay kinetics have been, however, rarely exploited as encoding parameter, although they cover time ranges which are not easily accessible with other luminophores. We demonstrate here the potential of QDs made from II/VI semiconductors with luminescence lifetimes of several 10 ns to expand the lifetime range of organic encoding luminophores in multiplexing applications using time-resolved flow cytometry (LT-FCM). For this purpose, two different types of QD-loaded beads were prepared and characterized by photoluminescence measurements on the ensemble level and by single-particle confocal laser scanning microscopy. Subsequently, these lifetime-encoded microbeads were combined with dye-encoded microparticles in systematic studies to demonstrate the potential of these QDs to increase the number of lifetime codes for lifetime multiplexing and combined multiplexing in the time and colour domain (tempo-spectral multiplexing). These studies were done with a recently developed novel luminescence lifetime flow cytometer (LT-FCM setup) operating in the time-domain, that presents an alternative to reports on phase-sensitive lifetime detection in flow cytometry. Flow cytometry (FCM), where either single cells or particles are optically detected in a flow, is an established and widespread multiparametric fluorescence technique used for many routine and research applications in biology, medical diagnostics, and food analysis 1-5. FCM typically relies on organic luminophores for optical encoding and multiplexing as well as analyte quantification 6-10. State-of-the-art FCM instruments are designed to detect spectral and/or intensity codes and can distinguish a large number of different colour and intensity codes, e.g. in the case of bead-based assays 5,11-13. Commonly applied spectral multiplexing approaches utilizing organic lumi-nophores are, however, limited by the spectral overlap of the emission bands of the different encoding dyes which limits the number of distinguishable codes and can require signal compensation and cross talk correction 6,14,15. The exploitation of the luminophore-characteristic luminescence lifetime (LT) as additional encoding parameter could in principle increase the number of accessible codes in flow cytometry analysis, thereby increasing the degree of multiplexing 6,7,14,16-21. Time-resolved fluorescence measurements in flow cytometry and lifetime encoding have been discussed for decades 8,22-28. The concept of lifetime multiplexing in a flow, however, has not been adopted in routine applications up to now due to the limited measurement time per object resulting in reduced photon count numbers 27,29. Moreover, the vast majority of reports on lifetime detection in flow cytometry relies on frequency-domain techniques (phase fluorometry), which used to be less expensive as fast detectors required for photon counting-based detection in the time domain, and present specific applications 8,9,14,18,28,30-32. This has been highlighted e.g., in a recently published comprehensive review article from J.P. Houston et al. 8 , revealing only a very small number of research articles related to cytometry studies in the time domain, mostly associated

Circulating cancer markers are metabolic products found in body fluids of cancer patients, which are specific for a certain type of malignant tumors. Cancer marker detection plays a key role in cancer diagnosis, treatment, and disease monitoring. The growing need for early cancer diagnosis requires quick and sensitive analytical approaches to detection of cancer markers. The approach based on the photonic crystal surface mode (PC SM) detection has been developed as a label-free high-precision biosensing technique. It allows real-time monitoring of molecular and cellular interactions using independent recording of the total internal reflection angle and the excitation angle of the PC surface wave. We used the PC SM technique for simultaneous detection of the ovarian cancer marker cancer antigen 125 and two breast cancer markers, human epidermal growth factor receptor 2 and cancer antigen 15-3. The new assay is based on the real-time flow detection of specific interaction between the antigens and capture antibodies. Its particular advantage is the possibility of multichannel recording with the same chip, which can be used for multiplexed detection of several cancer markers in a single experiment. The developed approach demonstrates high specificity and sensitivity for detection of all three biomarkers.

International audience; A novel suspension multiplex immunoassay for the simultaneous specific detection of lung cancer markers in bronchoalveolar lavage fluid (BALF) clinical samples based on fluorescent microspheres having different size and spectrally encoded with quantum dots (QDEM) was developed. The designed suspension immunoassay was validated for the quantitative detection of three lung cancer markers in BALF samples from 42 lung cancer patients and 10 control subjects. Tumor markers were detected through simultaneous formation of specific immune complexes consisting of a capture molecule, the target antigen, and biotinylated recognition molecule on the surface of the different QDEM in a mixture. The immune complexes were visualized by fluorescently labeled streptavidin and simultaneously analyzed using a flow cytometer. Preclinical validation of the immunoassay was performed and results were compared with those obtained using an alternative 3-plex immunoassay based on Luminex xMAP ® technology, developed on classical organic fluorophores. The comparison showed that the QDEM and xMAP ® assays yielded almost identical results, with clear discrimination between control and clinical samples. Thus, developed QDEM technology can become a good alternative to xMAP ® assays permitting analysis of multiple protein biomarkers using conventional flow cytometers.