Biology subjects

Conneely, L. J.

Publications and source records attributed to Conneely, L. J..

4 recordsLinked to original sources

bioRxiv2026

Developmental and regulatory logic of cannabis glandular trichomes resolved by single cell multiomics

Glandular trichomes of Cannabis sativa produce specialised metabolites including cannabinoids and terpenes, yet the cellular basis of trichome development and metabolic specialisation remains unresolved. Here we reconstruct the glandular trichome lineage within the C. sativa inflorescence using single-cell transcriptomics and chromatin accessibility profiling. We identify a continuous developmental trajectory from the protoderm, linking bulbous, sessile, and capitate-stalked trichomes, indicating that these morphologies represent sequential stages rather than distinct trichome types. We further identify a previously undescribed neck cell that shares a developmental origin with secretory disc cells before lineage bifurcation. Integration of chromatin accessibility with transcription factor (TF) binding reveals cell state specific regulatory programs coordinating neck cell development and specialised metabolism, redox homeostasis, and secretion in mature secretory disc cells. Methyl jasmonate elicitation induces extensive transcriptional and chromatin landscape reprogramming in mature secretory disc cells and transient repression of specialised metabolic pathways. Together, these findings provide a cell-resolved regulatory framework for glandular trichome development and function, revising prevailing models of trichome identity, maturation and defence associated metabolic regulation.

plant biology↗

bioRxiv2024

Characterization of the Cannabis sativa glandular trichome epigenome

BackgroundThe relationship between epigenomics and plant specialised metabolism remains largely unexplored despite the fundamental importance of epigenomics in gene regulation and, potentially, yield of products of plant specialised metabolic pathways. The glandular trichomes of Cannabis sativa are an emerging model system that produce large quantities of cannabinoid and terpenoid specialised metabolites with known medicinal and commercial value. To address the lack of epigenomic data in plant specialised metabolism, glandular trichomes, and C. sativa, we mapped H3K4 trimethylation, H3K56 acetylation, H3K27 trimethylation post-translational modifications and the histone variant H2A.Z, using chromatin immunoprecipitation, in glandular trichomes, leaf, and stem tissues. Corresponding transcriptomic (RNA-seq) datasets were integrated, and tissue-specific analyses conducted to relate chromatin states to glandular trichome specific gene expression. ResultsCannabinoid and terpenoid biosynthetic genes, specialised metabolite transporters, and defence related genes, were co-located with distal H3K56ac chromatin, a histone mark that flanks active distal enhancers in planta, exclusively in glandular trichomes. Glandular trichome specific H3K4 trimethylated chromatin was associated with genes involved in specialised metabolism and sucrose and starch metabolism. Bi-valent chromatin loci specific to glandular trichomes, marked with H3K4 trimethylation and H3K27 trimethylation, was associated with genes of MAPK signalling pathways and plant specialised metabolism pathways, supporting recent hypotheses that implicate bi-valent chromatin in plant defence. The histone variant H2A.Z was largely found in intergenic regions and enriched in chromatin that contained genes involved in DNA homeostasis. ConclusionWe report the first genome-wide histone post-translational modification maps for C. sativa glandular trichomes, and more broadly for glandular trichomes in plants. Our findings have implications in plant adaptation and stress response and provide a basis for enhancer-mediated, targeted, gene transformation studies in plant glandular trichomes.

plant biology↗

bioRxiv2020

Characterization of the Cannabis sativa glandular trichome proteome

Cannabis sativa has been cultivated since antiquity as a source of fibre, food and medicine. The recent resurgence of Cannabis as a cash crop is mainly driven by the medicinal and therapeutic properties of its resin, which contains compounds that interact with the human endocannabinoid system. Compared to other medicinal crops of similar value, however, little is known about the biology of C. sativa. Glandular trichomes are small hair-like projections made up of stalk and head tissue and are responsible for the production of the resin in C. sativa. Trichome productivity, as determined by Cannabis sativa resin yield and composition, is only beginning to be understood at the molecular level. In this study the proteomes of glandular trichome stalks and heads, were investigated and compared to the proteome of the whole flower tissue, to help elucidate Cannabis sativa glandular trichome biochemistry. The data suggested that the floral tissue acts as a major source of carbon and energy to the glandular trichome head sink tissue, supplying sugars which drive secondary metabolite biosynthesis in the glandular trichome head; the location of the secretory cells. The trichome stalk seems to play only a limited role in secondary metabolism and acts as both source and sink.

plant biology↗

bioRxiv2020

A partial pathogenicity chromosome in Fusarium oxysporum is sufficient to cause disease and can be horizontally transferred

During host colonization, plant pathogenic fungi secrete proteins, called effectors, to facilitate infection. Collectively, effectors may defeat the plant immune system, but usually not all effectors are equally important for infecting a particular host plant. In Fusarium oxysporum f.sp. lycopersici, all known effector genes - also called SIX genes - are located on a single accessory chromosome which is required for pathogenicity and can also be horizontally transferred to another strain. To narrow down the minimal region required for virulence, we selected partial pathogenicity chromosome deletion strains by fluorescence-assisted cell sorting of a strain in which the two arms of the pathogenicity chromosome were labelled with GFP and RFP, respectively. By testing the virulence of these deletion mutants, we show that the complete long arm and part of the short arm of the pathogenicity chromosome are not required for virulence. In addition, we demonstrate that smaller versions of the pathogenicity chromosome can also be transferred to a non-pathogenic strain and they are sufficient to turn the non-pathogen into a pathogen. Surprisingly, originally non-pathogenic strains that had received a smaller version of the pathogenicity chromosome were much more aggressive than recipients with a complete pathogenicity chromosome. Whole genome sequencing analysis revealed that partial deletions of the pathogenicity chromosome occurred mainly close to repeats, and that spontaneous duplication of sequences in accessory regions is frequent both in chromosome deletion strains and in horizontal transfer (recipient) strains. Author SummaryFungal genomes can often be divided into a core genome, which is essential for growth, and an accessory genome which is dispensable. The accessory genome in fungi can be beneficial under some conditions. For example, in some plant-pathogenic fungi, virulence genes are present in the accessory genome, which enable these fungi to cause disease on certain hosts. In Fusarium oxysporum f.sp. lycopersici, which infects tomato, all host-specific virulence genes are located on a single accessory chromosome. This pathogenicity chromosome can be horizontally transferred between strains. Here, we found that many suspected virulence genes are in fact not required for virulence because strains without a large part of the pathogenicity chromosome, including these genes, showed no reduced virulence. In addition, we demonstrate that partial pathogenicity chromosomes can be horizontally transferred to a non-pathogen. Surprisingly, originally non-pathogenic strains that had received a partial pathogenicity chromosome were more virulent than strains that had received the complete pathogenicity chromosome.

microbiology↗