Biology subjects

Sargent, D.

Publications and source records attributed to Sargent, D..

5 recordsLinked to original sources

bioRxiv2026

Trade-offs between photosynthetic capacity, mesophyll conductance stability and leaf anatomy shape heat and water deficit resilience in Gossypium.

O_LIMesophyll conductance (gm) governs CO2 diffusion to Rubisco and is a key determinant of photosynthetic performance, yet the mechanisms underlying its sensitivity to heat and water stress remain unresolved. C_LIO_LIWe quantified gm temperature responses across diverse Gossypium species and examined anatomical drivers of gm plasticity in cultivated cotton (G. hirsutum) and the wild Australian species G. bickii under elevated temperature and soil water deficit. C_LIO_LISpecies exhibited contrasting gm strategies: G. hirsutum exhibited high gm and carbon assimilation near thermal optima but showed greater sensitivity under combined heat and water deficit, whereas G. bickii maintained comparatively stable gm and photosynthesis across stress conditions. C_LIO_LIUnder water deficit, structural adjustments in G. hirsutum (increased leaf porosity, cell wall thickness and mesophyll surface exposure to intercellular airspaces) were insufficient to sustain gm, suggesting that liquid-phase resistances impose dominant constraints on CO2 diffusion under extreme climatic stress. C_LIO_LIThese results identify gm as a dynamic, multi-component trait and a key physiological vulnerability in cotton, shaped by coordinated anatomical characteristics and potentially cell wall properties and membrane-associated processes, with major implications for mechanistic photosynthesis modelling and improving climate resilience in cotton and other C3 species. C_LI

plant biology↗

bioRxiv2025

The control of prickle formation in Rubus

Prickles on blackberry and raspberry canes make pruning, harvesting, and handling more difficult and can increase labor costs for growers. The trait has been challenging to improve in these clonal crops because it is recessive and linked to undesirable agronomic traits. In blackberry and red raspberry, breeding programs have used recessive mutants at the S locus to generate prickleless cultivars for the last century. In this study, we identified independent loss-of-function mutations in a WUSCHEL-LIKE HOMEOBOX transcription factor, WOX1, as the genetic basis of the prickleless S locus in both blackberry and red raspberry. We mapped the S locus using integrated genome-wide association, bulked segregant analysis, and identity-by-descent analyses informed by breeding pedigrees. Additionally, we generated a genome sequence from Luther Burbanks prickleless blackberry variety Burbank Thornless that contained an additional allele of WOX1. To verify the genes role, we used gene editing to knock out WOX1 in an elite prickled commercial blackberry line. All edited plants were prickleless and lacked glandular trichomes, confirming that WOX1 controls a joint developmental pathway. Other plant traits were unchanged, indicating WOX1 is a specific and safe target for improvement. Gene editing can enable breeders to remove prickles directly from elite varieties, reducing the need for extensive breeding cycles and delivering safer, easier-to-harvest cultivars to growers.

plant biology↗

bioRxiv2025

Development of a Flex-Seq SNP panel for raspberry (Rubus idaeus L.) and validation through linkage map construction and identification of QTL for several traits of agronomic importance to raspberry breeding

High-throughput and reproducible genotyping platforms are critical for advancing genetic research and breeding in horticultural crops. Here, the development and validation of a custom single nucleotide polymorphism (SNP) panel using the Flex-Seq genotyping platform for red raspberry (Rubus idaeus L.) is described. SNPs were derived from existing linkage maps and RNA-seq data, resulting in a panel of 5,639 high-confidence, bi-allelic markers distributed across the seven chromosomes of the R. idaeus Malling Jewel reference genome. The panel was used to genotype 457 red raspberry accessions including 161 individuals from a bi-parental mapping population (Parisx486), enabling the construction of high-density linkage maps and the identification of quantitative trait loci (QTL) for fruit size, leaf colour, plant vigour, and thorn density. Genome-wide association studies (GWAS) identified a major QTL for thornlessness on chromosome 4, co-locating with a candidate HOX3 gene, and multiple QTLs associated with anthocyanin biosynthesis genes for leaf colour. The SNP panel demonstrated utility for linkage mapping and trait association analyses, offering a powerful resource for marker-assisted selection and genetic improvement in red raspberry.

genomics↗

bioRxiv2018

Population genome sequencing of the scab fungal species Venturia inaequalis, Venturia pirina, Venturia aucupariae and Venturia asperata.

The Venturia genus comprises fungal species that are pathogens on Rosaceae host plants, including V. inaequalis and V. asperata on apple, V. aucupariae on sorbus and V. pirina on pear. Although the genetic structure of V. inaequalis populations has been investigated in detail, genomic features underlying these subdivisions remain poorly understood. Here, we report whole genome sequencing of 87 Venturia strains that represent each species and each population within V. inaequalis. We present a PacBio genome assembly for the V. inaequalis EU-B04 reference isolate. The size of selected genomes was determined by flow cytometry, and varied from 45 to 93 Mb. Genome assemblies of V. inaequalis and V. aucupariae contain a high content of transposable elements (TEs), most of which belong to the Gypsy or Copia LTR superfamilies and have been inactivated by Repeat-Induced Point mutations. The reference assembly of V. inaequalis presents a mosaic structure of GC-equilibrated regions that mainly contain predicted genes and AT-rich regions, mainly composed of TEs. Six pairs of strains were identified as clones. Single-Nucleotide Polymorphism (SNP) analysis between these clones revealed a high number of SNPs that are mostly located in AT-rich regions due to misalignments and allowed determining a false discovery rate. The availability of these genome sequences is expected to stimulate genetics and population genomics research of Venturia pathogens. Especially, it will help understanding the evolutionary history of Venturia species that are pathogenic on different hosts, a history that has probably been substantially influenced by TEs.

plant biology↗

bioRxiv2018

Investigating the neuroprotective effect of AAV-mediated β-synuclein overexpression in a transgenic model of synucleinopathy

Parkinsons disease (PD) and multiple system atrophy (MSA) are neurodegenerative diseases characterized by inclusions mainly composed of -synuclein (-syn) aggregates. The objective of this study was to investigate if {beta}-synuclein ({beta}-syn) overexpression could have beneficial effects by inhibiting the aggregation of -syn. The M83 transgenic mouse is a model of synucleinopathy, which develops severe motor symptoms associated with aggregation of -syn. M83 neonate or adult mice were injected with adeno-associated virus vectors carrying the human {beta}-syn gene (AAV{beta}-syn) or green fluorescent protein gene (AAVGFP) using different injection sites. One or two months later, M83 disease was accelerated or not using brain M83 extracts from mouse (M83) or human (MSA) origins. AAV mediated {beta}-syn overexpression detected by ELISA did not delay the disease onset, regardless of the AAV injection route and of the inoculation of brain extracts. Accordingly, phosphorylated -syn levels detected by ELISA in sick mice were similar after injecting AAV{beta}-syn or AAVGFP. Instead, immunohistochemistry analysis of {beta}-syn indicated the presence of proteinase-K resistant {beta}-syn staining specifically in sick M83 mice inoculated with AAV{beta}-syn. This study indicated for the first time that {beta}-syn could form aggregates in a model of synucleinopathy when it is expressed by a viral vector.

neuroscience↗