Biology subjects

Luan, S.

Publications and source records attributed to Luan, S..

7 recordsLinked to original sources

bioRxiv2026

Chromosomal rearrangements 1 and sequence similarity drivepreferential allosyndetic introgression from a wild relative into wheat

Recombination in polyploid genomes is generally constrained to homologous or homoeologous chromosomes; however, how chromosomal rearrangements influence recombination between chromosomes remains unclear. Here, we demonstrate that large-scale chromosomal rearrangements in the wild relatives of wheat are associated with recombination involving non-homoeologous chromosomes or arms during alien gene introgression under conditions that permit homoeologous recombination mediated by ph1b. Using a wheat chromosome 6A monosomic-induced 6AS*6CL Robertsonian translocation combined with ph1b-mediated recombination, we generated 17 independent recombinants carrying a new stem rust resistance gene, Sr69, from Aegilops caudata chromosome arm 6CL. Unexpectedly, 94.1% (16 of 17) of recombinants resulted from exchanges with wheat group-7 chromosomes rather than with the homoeologous group-6 chromosome. Comparative sequence- and marker-based analyses identified a 67-Mb rearranged interval on Ae. caudata 6CL that corresponds to telomeric regions of the long arms of wheat group-7 chromosomes. Sequence similarity within this interval was quantitatively associated with recombination frequency, with higher similarity corresponding to more frequent translocations. Physical and optical mapping showed that recombination within the rearranged interval generated compensating 7A/6C, 7B/6C, and 7D/6C translocations, whereas recombination outside this region produced non-compensating 6A/6C exchanges. An independent case involving the powdery mildew resistance gene Pm7C showed a similar correspondence between a rearranged 7CL region and preferential introgression into wheat 7DS. Together, these results indicate that ph1b-mediated recombination involving structurally altered chromosomes is driven by local chromosomal structure and sequence similarity rather than strict homoeologous group identity. This provides a mechanistic basis for harnessing untapped beneficial genes from structurally rearranged alien genomes. Significance StatementAlien gene introgression is a powerful strategy for wheat improvement, typically relying on ph1b-mediated recombination between homoeologous chromosomes. The genomic basis and outcomes of introgression from structurally rearranged alien chromosomes remain unclear. Here, we show that ph1b-induced recombination can efficiently target wheat-allosyntenic blocks in rearranged alien genomes, preferentially transferring genes from structurally altered alien segments into their syntenic regions on wheat chromosomes of different homoeologous groups. Crossover formation is governed by extended sequence similarity within corresponding intervals rather than strict collinearity across entire homoeologous chromosomes. As many wild species exhibit extensive genome rearrangement, these findings and methodologies expand access to underexploited genetic diversity embedded within highly rearranged wild genomes for wheat improvement.

genetics↗

bioRxiv2023

The activated plant NRC4 immune receptor forms a hexameric resistosome

Innate immune responses against microbial pathogens in both plants and animals are regulated by intracellular receptors known as Nucleotide-binding Leucine-rich Repeats (NLR) proteins. In plants, these NLRs play a crucial role in recognizing pathogen effectors, thereby initiating the activation of immune defense mechanisms. Notably, certain NLRs serve as "helper" NLR immune receptors (hNLR), working in tandem with "sensor" NLR immune receptors (sNLR) counterparts to orchestrate downstream signaling events to express disease resistance. In this study, we reconstituted and determined the cryo-EM structure of the hNLR required for cell death 4 (NRC4) resistosome. The auto-active NRC4 formed a previously unanticipated hexameric configuration, triggering immune responses associated with Ca2+ influx into the cytosol. Furthermore, we uncovered a dodecameric state of NRC4, where the coil-coil (CC) domain is embedded within the complex, suggesting an inactive state, and expanding our understanding of the regulation of plant immune responses. One Sentence SummaryThe hexameric NRC4 resistosome mediates cell death associated with cytosolic Ca2+ influx.

plant biology↗

bioRxiv2023

Regulated Cleavage and Relocation of FERONIA Control Immunity in Arabidopsis Roots

Plant roots exhibit localized immunity (LI) specifically in the root cap and transition/elongation zone (TZ/EZ). Such immunity relies on receptor-like kinases localized at the plasma membrane (PM), which are essential for plant response to bacteria in the rhizosphere. Here, we identified a new mechanism of action for receptor kinase FERONIA (FER) in LI. In the absence of bacterial stimuli, FER is localized to the PM, maintaining plant growth. When confronted with bacterial colonization, RALF23 peptide hyper-accumulates in TZ/EZ cells and activates a metalloproteinase that cleaves FER and transfer the cytosolic kinase domain into the nucleus. The nucleus-localized kinase domain of FER contributes to LI by reducing bacterial abundance at TZ/EZ. Thus, this work uncovered a unique mechanism by which a single receptor kinase acts in two molecular forms and two distinct subcellular locations to balance growth and immunity. One Sentence SummaryBacteria induces the cleavage of FER via At2-MMP to trigger a localized immunity around TZ and EZ of Arabidopsis roots.

plant biology↗

bioRxiv2022

Arabidopsis MLO4 Functions as a Ca2+ Channel Essential for Mechanosensing in Root Tips

Mechanical stimuli guide root growth to avoid obstacles in the soil. Although mechanisms underlying root mechanosensing remain largely unknown, calcium signaling is proposed to be an early event that proceeds directional root growth. In response to mechanical perturbations, root cells produce transient spikes in the cytosolic free Ca2+ levels. Loss-of-function mutations of MLOs cause root curling upon contact with hard surface of obstacles, the mechanism for MLOs action in root thigmomorphogenesis has been enigmatic. WT and mlo4 seedlings were grown on MS media containing gradient agar concentrations mimicking different levels of soil hardness and compared their root growth into the agar gradient mlo4 had much less roots penetrated the harder agar barrier as compared to WT roots. The channel activity of MLO4 was examined in Xenopus oocytes using the two-electrode voltage clamp (TEVC) method. The TEVC recording showed that the oocytes injected with MLO cRNA displayed large inward currents in the presence of Ca2+. MLO4 rescued the cch1/mid1 from growth arrest by the pheromone, these results indicate that MLO4 constitutes a novel Ca2+-permeable channel. Ca2+ spike was hardly detectable in mlo4/GCaMP6s seedings in response to a hard surface during root elongation. In summary, MLO4 functions as a typical Ca2+ channel that links touch stimulation to Ca2+ elevation in root tip cells.

plant biology↗

bioRxiv2022

HPCA1 is required for systemic ROS and calcium cell-to-cell signaling and plant acclimation to stress

As multicellular organisms, plants constantly balance and coordinate many metabolic, physiological, and molecular responses between different cell types and tissues. This process is essential for plant development, growth, and response to different environmental cues. Because plants lack a nervous system, they transmit different signals over long distances via cell-to-cell signaling. Recent studies revealed that reactive oxygen species (ROS), produced by respiratory burst oxidase homologs (RBOHs) at the apoplast play a key role in cell-to-cell signaling. A state of enhanced ROS production by one cell is thereby sensed by a neighboring cell, causing it to produce ROS, creating a continuous chain of cell-to-cell ROS accumulation termed the ROS wave. This process was found to mediate systemic signals throughout the plant and is required for plant acclimation to different stresses. Although RBOHs were found to produce ROS essential for this process, the identity of the receptor(s) perceiving the apoplastic ROS signal is currently unknow. Here we reveal that the leucine-rich-repeat receptor-like kinase HPCA1 (H2O2-induced Ca2+ increases 1) acts as a central ROS receptor required for the propagation of cell-to-cell ROS signals, systemic signaling in response to different biotic and abiotic stresses, and plant acclimation to stress. We further report that HPCA1 is required for systemic calcium signals, but not systemic membrane depolarization responses, and identify key calcium-dependent signal transduction proteins involved in this process. Our findings reveal that HPCA1 plays a key role in mediating and coordinating systemic cell-to-cell ROS and calcium signals that are required for plant acclimation to stress.

plant biology↗

bioRxiv2021

The exosomes derived from urine of premature infants target MAPK8 via miR-30a-5p to protect cisplatin-induced acute kidney injury in mice

AimAcute kidney injury (AKI), a global public health issue, not only causes millions of deaths every year, but is also a susceptible factor for chronic kidney disease (CKD). Nephrotoxic drugs are an important cause of AKI. There is still a lack of effective and satisfactory prevention method in clinical practice. This study investigated the protective effect of the exosomes derived from urine of premature infants on cisplatin-induced acute kidney injury. MethodsIsolation of exosomes from fresh urine of premature infants: The characteristics of exosomes were determined by flow cytometry, transmission electron microscopy and Western blotting. A C57BL/6 mice model of cisplatin-induced acute kidney injury was established. The mice in the experimental group were given 100ug exosomes dissolved in 200ul solution. The mice in the control group were given normal saline (200ul). These treatments were performed 24 hours after AKI was induced by intraperitoneal injection of cisplatin. To evaluate renal function, blood was drawn 24 hours after AKI model was established and serum creatinine (sCr) was measured. The mice were euthanized 72 hours after exosome treatment. The kidneys were collected for pathological examination, RNA and protein extraction, and the evaluation of renal tubular damage and apoptosis. In the in-vitro experiment, human renal cortex/proximal tubular cells (HK2) was induced by cisplatin to assess the protective ability of the exosomes derived from urine of premature infants. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western Blotting were used to evaluate the effect of exosomes treatment on the apoptosis of HK2 cells induced by cisplatin. Exosome microRNA sequencing technology and bioinformatics analysis method were applied to investigate the miRNAs enriched in exosomes and their target genes. The dual luciferase gene reporter system was used to detect the interaction of target genes. ResultsTreatment of exosomes derived from urine of premature infants could decrease the level of serum creatinine and the apoptosis of renal tubular cell, inhibit the infiltration of inflammatory cell, protect mice from acute kidney injury induced by cisplatin and reduce mortality. In addition, miR-30a-5p was the most abundant miRNA in the exosomes derived from urine of premature infants. It protected HK2 cells from cisplatin-induced apoptosis by targeting and down-regulating the 3UTR of mitogen-activated protein kinases (MAPK8) mRNA. ConclusionsAccording to our results, the exosomes derived from urine of premature infants alleviated cisplatin-induced acute kidney injury in mice and inhibited the apoptosis of human proximal tubular cells (HK2) induced by cisplatin in vitro. MiR-30a-5p in exosomes inhibited cisplatin-induced MAPK activation, ameliorated apoptosis, and protected renal function. The exosomes derived from urine of premature infants provided a promising acellular therapy for AKI.

molecular biology↗

bioRxiv2017

Compact Standalone Platform for Neural Recording with Real-Time Spike Sorting and Data Logging

ObjectiveLongitudinal observation of single unit neural activity from large numbers of cortical neurons in awake and mobile animals is often a vital step in studying neural network behaviour and towards the prospect of building effective Brain Machine Interfaces (BMIs). These recordings generate enormous amounts of data for transmission & storage, and typically require offline processing to tease out the behaviour of individual neurons. Our aim was to create a compact system capable of: 1) reducing the data bandwidth by circa 3 orders of magnitude (greatly improving battery lifetime and enabling low power wireless transmission); 2) producing real-time, low-latency, spike sorted data; and 3) long term untethered operation. Approach. We have developed a headstage that operates in two phases. In the short training phase a computer is attached and classic spike sorting is performed to generate templates. In the second phase the system is untethered and performs template matching to create an event driven spike output that is logged to a micro-SD card. To enable validation the system is capable of logging the high bandwidth raw neural signal data as well as the spike sorted data. Main results. The system can successfully record 32 channels of raw neural signal data and/or spike sorted events for well over 24 hours at a time and is robust to power dropouts during battery changes as well as SD card replacement. A 24-hour initial recording in a non-human primate M1 showed consistent spike shapes with the expected changes in neural activity during awake behaviour and sleep cycles. Significance The presented platform allows neural activity to be unobtrusively monitored and processed in real-time in freely behaving untethered animals revealing insights that are not attainable through scheduled recording sessions and provides a robust, low-latency, low-bandwidth output suitable for BMIs, closed loop neuromodulation, wireless transmission and long term data logging.

bioengineering↗