Biology subjects

Bennett, M.

Publications and source records attributed to Bennett, M..

4 recordsLinked to original sources

bioRxiv2018

A network of transcriptional repressors mediates auxin response specificity

INTRODUCTORY PARAGRAPHThe regulation of signalling capacity plays a pivotal role in setting developmental patterns in both plants and animals (1). The hormone auxin is a key signal for plant growth and development that acts through the AUXIN RESPONSE FACTOR (ARF) transcription factors (2). A subset of these ARFs comprises transcriptional activators of target genes in response to auxin, and are essential for regulating auxin signalling throughout the plant lifecycle (3). While ARF activators show tissue-specific expression patterns, it is unknown how their expression patterns are established. Chromatin modifications and accessibility studies revealed the chromatin of loci encoding ARF activators is constitutively open for transcription. Using a high-throughput yeast one-hybrid (Y1H) approach, we discovered a network of transcriptional regulators of ARF activator genes from Arabidopsis thaliana. Expression analyses demonstrated that the majority of these regulators act as repressors of ARF transcription in planta. Our observations support a scenario where the default configuration of open chromatin enables a network of transcriptional repressors to shape the expression pattern of ARF activators and provide specificity in auxin signalling output throughout development.

plant biology↗

bioRxiv2018

Nucleosome remodelling at origins of Global Genome-Nucleotide Excision Repair occurs at the boundaries of higher-order chromatin structure

Repair of UV-induced DNA damage requires chromatin remodeling. How repair is initiated in chromatin remains largely unknown. We recently demonstrated that Global Genome Nucleotide Excision Repair (GG-NER) in chromatin is organized into domains around open reading frames. Here, we identify these domains, and by examining DNA damage-induced changes in the linear structure of nucleosomes, we demonstrate how chromatin remodeling is initiated during repair. In undamaged cells, we show that the GG-NER complex occupies chromatin at nucleosome free regions of specific gene promoters. This establishes the nucleosome structure at these genomic locations, which we refer to as GG-NER complex binding sites (GCBSs). We demonstrate that these sites are frequently located at genomic boundaries that delineate chromasomally interacting domains (CIDs). These boundaries define domains of higher-order nucleosome-nucleosome interaction. We show that efficient repair of DNA damage in chromatin is initiated following disruption of H2A.Z-containing nucleosomes adjacent to GCBSs by the GG-NER complex.

genomics↗

bioRxiv2018

Wheat shovelomics II: Revealing relationships between root crown traits and crop growth

Optimization of root system architecture represents an important goal in wheat breeding. Adopting new field methods for root phenotyping is key to delivering this goal. A novel shovelomics method was applied for phenotyping root crown traits to characterize the Savannah x Rialto doubled-haploid (DH) population in two field experiments under irrigated and rain-fed conditions. Trait validation was carried out through soil coring on a subset of 14 DH lines and the two parents. We observed that drought reduced grain yield per plant by 21.0%. Under rain-fed conditions, nodal root angle and roots shoot-1 were positively associated with root length density (RLD) at 40-60 cm depth; RLD was also positively correlated with grain yield. Nodal root angle and roots shoot-1 were also positively associated with canopy stay green and grain yield under rain-fed conditions. We conclude that shovelomics is a valuable technique for quantifying genetic variation in nodal root traits in wheat, revealing nodal root angle and root number per shoot provide useful selection criteria in breeding programs aimed at improving drought tolerance in wheat.\n\nHighlightNodal root angle and number shoot-1 measured using shovelomics were positively associated with root density at depth and yield under drought in a Savanah x Rialto wheat DH population.

plant biology↗

bioRxiv2018

Cell death in cells overlying lateral root primordia contributes to organ growth in Arabidopsis

Unlike animal development, plant organ growth is widely accepted to be determined by cell division without any contribution of cell elimination. We investigated this paradigm during Arabidopsis lateral root formation when growth of the new primordia (LRP) from pericycle-derived stem cells deep inside the root is reportedly facilitated by remodeling of the walls of overlying cells without apparent cell death. However, we observed the induction of marker genes for cell types undergoing developmental cell death in several cells overlying the growing LRP. Transmission electron microscopy, time-lapse confocal and light sheet microscopy techniques were used to establish that cell death occurred at least in a subset of endodermal LRP-overlying cells during organ emergence. Significantly, organ emergence was retarded in mutants lacking a positive cell death regulator, and restored by inducing cell death in cells overlying LRP. Hence, we conclude that in the case of LRP, cell elimination contributes to organ growth.

plant biology↗