Biology subjects

Parra, L.

Publications and source records attributed to Parra, L..

6 recordsLinked to original sources

bioRxiv2026

Fendioxypyracil Exhibits Potent Inhibition of PPO-Resistant Mutant Enzymes and Robust Activity Against PPO-Resistant Amaranthus

Background: Resistance to protoporphyrinogen oxidase (PPO) inhibiting herbicides is mainly driven by diverse target-site mutations, reducing the effectiveness of this site of action in row crop systems. Fendioxypyracil is a newly developed PPO inhibitor with high intrinsic grass and broadleaf activity, but its performance against resistant populations and target-site enzyme variants remains insufficiently characterized. Results: Enzyme assays using PPO2 from Amaranthus palmeri and Setaria viridis demonstrated that fendioxypyracil maintained low IC50 values across a broad range of resistance associated mutations, including dG210 deletion and G210, R128, and G399 substitutions, whereas oxadiazon, tiafenacil, and saflufenacil showed substantial loss of potency. Greenhouse dose response experiments confirmed strong fendioxypyracil efficacy, with susceptible and G399A populations controlled at <3 g ai/ha, while dG210 and R128G populations showed only moderate shifts in sensitivity but remained effectively controlled at the recommended rate. Transgenic Arabidopsis thaliana expressing resistant PPX2 alleles exhibited faster and more severe injury with fendioxypyracil compared to saflufenacil. Field trials conducted in a PPO resistant Amaranthus palmeri population demonstrated that fendioxypyracil provided consistent weed control and density reduction, matching the performance of trifludimoxazin and saflufenacil while exceeding that of fomesafen. Conclusion: Fendioxypyracil provides robust and broad-spectrum activity against PPO resistant Amaranthus populations and target mutant enzymes, maintaining efficacy across diverse mutation backgrounds. These results demonstrate its potential as an effective tool for managing PPO inhibitor resistance and sustaining weed control in row-crop production systems.

molecular biology↗

bioRxiv2026

Fendioxypyracil, a new and systemic PPO-inhibiting herbicide for X-spectrum weed control

BackgroundFendioxypyracil is a novel protoporphyrinogen oxidase (PPO)-inhibiting herbicide (HRAC Group 14) developed to address the increasing prevalence of herbicide-resistant weeds and to expand available weed control options. PPO inhibitors disrupt chlorophyll biosynthesis by blocking the conversion of protoporphyrinogen IX to protoporphyrin IX, resulting in light-promoted formation of reactive oxygen species and rapid plant necrosis. Building on established PPO chemistry, fendioxypyracil incorporates a pyridine-based core and an aryloxy sidechain designed to enhance binding affinity and post-emergence activity. ResultsGreenhouse evaluations demonstrated high efficacy of fendioxypyracil against key grass weeds, including wild oat (Avena fatua), crabrass (Digitaria Sanginalis), goosegrass (Eleusina indica) and barnyard grass (Echinochloa crus-galli), as well as strong control of major broadleaf species. Physiological characterization and enzyme inhibition assays confirmed PPO as the primary site and mode of action, with IC values lower than those of the commercial standard saflufenacil for both PPO isoforms. ConclusionFendioxypyracil represents a next-generation PPO inhibitor with broad-spectrum and systemic activity, offering a valuable new tool for integrated weed management. Its high biological activity and efficacy across multiple weed taxa supports its potential to enhance on-farm weed control strategies and contributes to resistance management programs.

plant biology↗

bioRxiv2024

Engineering the plant intracellular immune receptor Sr50 to restore recognition of the AvrSr50 escape mutant

Pathogen-driven plant diseases cause significant crop losses worldwide. The introgression of intracellular nucleotide-binding leucine-rich repeat receptor (NLR) genes into elite crop cultivars is a common strategy for disease control, yet pathogens rapidly evolve to evade NLR-mediated immunity. The NLR gene Sr50 protects wheat against stem rust, a devastating disease caused by the fungal pathogen Puccinia graminis f. sp. tritici (Pgt). However, mutations in AvrSr50 allowed Pgt to evade Sr50 recognition, leading to resistance breakdown. Advances in protein structure modeling can enable targeted NLR engineering to restore recognition of escaped effectors. Here, we combined iterative computational structural analyses and site-directed mutagenesis to engineer Sr50 recognition of AvrSr50QCMJC, a Pgt effector variant that evades wild-type Sr50 detection. Derived by molecular docking, our initial structural model identified the K711D substitution in Sr50, which partially restored AvrSr50QCMJC recognition. Enhancing Sr50K711D expression via strong promoters compensated for weak recognition and restored robust immune responses. Further structural refinements led to the generation of five double and two triple receptor mutants. These engineered mutants, absent in nature, showed robust dual recognition for AvrSr50 and AvrSr50QCMJC in both Nicotiana benthamiana and wheat protoplasts. Notably, the K711D substitution was essential and synergistic with the additional substitutions for AvrSr50QCMJC recognition, demonstrating protein epistasis. Furthermore, this single substitution altered AlphaFold 2 predictions, enabling accurate modeling of the Sr50K711D-AvrSr50 complex structure, consistent with our final structural hypothesis. Collectively, this study outlines a framework for NLR engineering to counteract pathogen adaptation and provides novel Sr50 variants with potential for stem rust resistance.

plant biology↗

bioRxiv2023

Pupil size and EEG speech tracking as independent measures of listening effort and speech intelligibility

Speech is hard to understand when there is background noise. Speech intelligibility and listening effort both affect our ability to understand speech, but the relative contribution of these subjective factors is hard to disentangle. Previous studies suggest that speech intelligibility could be assessed with EEG speech tracking and listening effort via pupil size. However, these measures may be confounded, because poor intelligibility may require a larger effort. To address this we developed a novel word-detection paradigm that allows for a rapid behavioral assessment of speech processing. In this paradigm words appear on the screen during continuous speech similar to closed captioning. In two listening experiments with a total of 51 participants we manipulated intelligibility with changing auditory noise levels and modulated effort by varying monetary reward. Increasing signal-to-noise ratio (SNR) improved detection performance along with EEG speech tracking, suggesting improved intelligibility. Additionally, we find larger pupil size with increased SNR, suggestive of increased effort. Surprisingly, when we modulated both reward and SNR, we found that reward modulated only pupil size, while SNR modulated only EEG speech tracking. We suggest that this new paradigm can be used to independently and objectively assess speech intelligibility and listening effort.

neuroscience↗

bioRxiv2022

Saccadic modulation of neural excitability in auditory areas of the neocortex

SummaryIn natural "active" vision, humans and other primates use eye movements (saccades) to sample bits of information from visual scenes. In this process, nonretinal signals linked to saccades shift visual cortical neurons to a high excitability state as each saccade ends. The extent of this saccadic modulation outside of the visual system is unknown. Here, we show that during natural viewing, saccades modulate excitability in numerous auditory cortical areas, with a pattern complementary to that seen in visual areas. Bi-directional functional connectivity patterns suggest that these effects may arise from regions involved in saccade generation. By using saccadic signals to yoke excitability states in auditory areas to those in visual areas, the brain can improve information processing in complex natural settings.

neuroscience↗

bioRxiv2017

The Healthy Brain Network Biobank: An open resource for transdiagnostic research in pediatric mental health and learning disorders

Technological and methodological innovations are equipping researchers with unprecedented capabilities for detecting and characterizing pathologic processes in the developing human brain. As a result, ambitions to achieve clinically useful tools to assist in the diagnosis and management of mental health and learning disorders are gaining momentum. To this end, it is critical to accrue large-scale multimodal datasets that capture a broad range of commonly encountered clinical psychopathology. The Child Mind Institute has launched the Healthy Brain Network (HBN), an ongoing initiative focused on creating and sharing a biobank of data from 10,000 New York area participants (ages 5-21). The HBN Biobank houses data about psychiatric, behavioral, cognitive, and lifestyle phenotypes, as well as multimodal brain imaging (resting and naturalistic viewing fMRI, diffusion MRI, morphometric MRI), electroencephalography, eye-tracking, voice and video recordings, genetics, and actigraphy. Here, we present the rationale, design and implementation of HBN protocols. We describe the first data release (n = 664) and the potential of the biobank to advance related areas (e.g., biophysical modeling, voice analysis).

neuroscience↗