Biology subjects

Bancroft, I.

Publications and source records attributed to Bancroft, I..

4 recordsLinked to original sources

bioRxiv2023

Primary multistep phosphorelay activation comprises both cytokinin and abiotic stress responses in Brassicaceae

Multistep phosphorelay (MSP) signaling integrates hormonal and environmental signals to control plant development and adaptive responses. The type-A RESPONSE REGULATORs (RRAs), the downstream members of the MSP cascade and cytokinin primary response genes, are supposed to mediate primarily the negative feedback regulation of (cytokinin-induced) MSP signaling. However, the transcriptional data suggest the involvement of RRAs in stress-related responses as well. By employing evolutionary conservation with the well-characterized Arabidopsis thaliana RRAs, we identified 5 and 38 novel putative RRAs in Brassica oleracea and Brassica napus, respectively. Our phylogenetic analysis suggests the existence of gene-specific selective pressure, maintaining the homologs of ARR3, ARR6, and ARR16 as singletons during the evolution of Brassica oleracea and Brassica rapa. We categorized RRAs based on the kinetics of their cytokinin-mediated upregulation and observed both similarities and specificities in this type of response across Brassicaceae. Using bioinformatic analysis and experimental data demonstrating the cytokinin responsiveness of Arabidopsis-derived TCSv2 reporter, we unveil the mechanistic conservation of cytokinin-mediated upregulation of RRAs in Brassica rapa and Brassica napus. Notably, we identify partial cytokinin dependency of cold stress-induced RRA transcription, thus corroborating the role of cytokinin signaling in the crop adaptive responses. HighlightsWe identified Brassica homologs of Arabidopsis type-A response regulators (RRAs), demonstrate existence of selective pressure preventing several RRAs multiplication during Brassicaceae evolution and describe cytokinin dependency of cold-induced RRAs upregulation.

plant biology↗

bioRxiv2020

Validation of a novel associative transcriptomics pipeline in Brassica oleracea: Identifying candidates for vernalisation response

Associative transcriptomics has been used extensively in Brassica napus to enable the rapid identification of markers correlated with traits of interest. However, within the important vegetable crop species, Brassica oleracea, the use of associative transcriptomics has been limited due to a lack of fixed genetic resources and the difficulties in generating material due to self-incompatibility. Within Brassica vegetables, the harvestable product can be vegetative or floral tissues and therefore synchronisation of the floral transition is an important goal for growers and breeders. Vernalisation is known to be a key determinant of the floral transition, yet how different vernalisation treatments influence flowering in B. oleracea is not well understood. Here, we present results from phenotyping a diverse set of 69 B. oleracea accessions for heading and flowering traits under different environmental conditions. We developed a new associative transcriptomics pipeline, and inferred and validated a population structure, for the phenotyped accessions. A genome-wide association study identified miR172D as a candidate for the vernalisation response. Gene expression marker association identified variation in expression of BoFLC.C2 as a further candidate for vernalisation response. This study provides insights into the genetic basis of vernalisation response in B. oleracea through associative transcriptomics and confirms its characterisation as a complex G x E trait. Candidate leads were identified in miR172D and BoFLC.C2. These results could facilitate marker-based breeding efforts to produce B. oleracea lines with more synchronous heading dates, potentially leading to improved yields.

plant biology↗

bioRxiv2020

High contiguity long read assembly of Brassica nigra allows localization of active centromeres and provides insights into the ancestral Brassica genome.

High-quality nanopore genome assemblies were generated for two Brassica nigra genotypes (Ni100 and CN115125); a member of the agronomically important Brassica species. The N50 contig length for the two assemblies were 17.1 Mb (58 contigs) and 0.29 Mb (963 contigs), respectively, reflecting recent improvements in the technology. Comparison with a de novo short read assembly for Ni100 corroborated genome integrity and quantified sequence related error rates (0.002%). The contiguity and coverage allowed unprecedented access to low complexity regions of the genome. Pericentromeric regions and coincidence of hypo-methylation enabled localization of active centromeres and identified a novel centromere-associated ALE class I element which appears to have proliferated through relatively recent nested transposition events (<1 million years ago). Computational abstraction was used to define a post-triplication Brassica specific ancestral genome and to calculate the extensive rearrangements that define the genomic distance separating B. nigra from its diploid relatives.

genomics↗

bioRxiv2018

Genome-wide selection footprints and deleterious variations in young Asian allotetraploid rapeseed

Brassica napus (AACC, 2n=38), is an important oilseed crop grown worldwide. However, little is known about the population evolution of this species, the genomic difference between its major genetic clusters, such as European and Asian rapeseed, and impacts of historical large-sale introgression events in this young tetraploid. In this study, we reported the de novo assembly of the genome sequences of an Asian rapeseed (B. napus), Ningyou 7 and its four progenitors and carried out de novo assembly-based comparison, pedigree and population analysis with other available genomic data from diverse European and Asian cultivars. Our results showed that Asian rapeseed originally derived from European rapeseed, but it had subsequently significantly diverged, with rapid genome differentiation after intensive local breeding selection. The first historical introgression of B. rapa dramatically broadened the allelic pool of Asian B. napus, but decreased their deleterious variations. The secondary historical introgression of European rapeseed (canola-quality) has reshaped Asian rapeseed into two groups, accompanied by an increase in genetic load. This study demonstrates distinctive genomic footprints by recent intra- and inter-species introgression events for local adaptation, and provide novel insights for understanding the rapid genome evolution of a young allopolyploid crop.

genomics↗