Simon Bull


Last Name

Bull

First Name

Simon

ORCID

0000-0003-0506-6984

Organisational unit

03707 - Zeeman, Samuel C. / Zeeman, Samuel C.

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Publications 1 - 10 of 30
  • Towards restoring self-incompatibility in inbred crops – a pilot study in Brachypodium distachyon
    Item type: Other Conference Item
    Kupper, Daniela; Kupper, Daniela; Manzanares, Chloe; et al. (2025)
    Self-incompatibility (SI) is present in over half of the angiosperms. It serves to promote outcrossing and increase genetic diversity in plant populations. In allogamous Poaceae species, SI is governed by a unique gametophytic system based on two multi-allelic loci, S and Z. Rohner et al. (2023) identified the genes responsible for the initial self-recognition in perennial ryegrass (Lolium perenne L.). Both the S and the Z loci comprise three genes: two pollen-expressed genes encoding a transmembrane protein (DUF247, male determinants) and one stigma-expressed secreted peptide (female determinant). Using Brachypodium distachyon (L.) as a model, we aim at restoring SI in this otherwise self-compatible grass species, thereby providing functional validation of the SI genes identified in L. perenne. The six SI genes, along with the native promoters of two, were cloned into a single 40.3 kb DNA vector construct for stable plant transformation. Transcriptional reporter lines containing mCitrine are also being developed to confirm spatio-temporal expression in B. distachyon. Preliminary results show that the promoter of the female SI component from L. perenne is driving stigma-specific expression in B. distachyon. These results provide a first indication of the feasibility of restoring SI by transferring L. perenne genes into B. distachyon. Using B. distachyon will allow us to bypass the vernalization and transformation bottlenecks in L. perenne and accelerate studies of the physiological and biological mechanisms underlying SI in grasses. Moreover, these studies will set a precedent for restoring SI in other crop species and bring new tools for plant breeders. References: Rohner M., Manzanares C., Yates S., Thorogood D., Copetti D., Lübberstedt T., Asp T., and Studer B, 2023. Fine-mapping and comparative genomic analysis reveal the gene composition at the S and Z self-incompatibility loci in grasses. Mol Biol Evol. 40 (1).
  • Occurrence of Sweet potato leaf curl virus in Sicily
    Item type: Other Journal Item
    Briddon, Rob W.; Bull, Simon; Bedford, Ian D. (2006)
    Plant Pathology
  • Implementation of genome editing for apple breeding
    Item type: Other Conference Item
    Stähli, David; Bull, Simon; Studer, Bruno; et al. (2019)
    Book of Abstracts: 1st PlantEd Conference Plant Genome Editing - State of the Art
  • Ascorbic Acid Biofortification in Crops
    Item type: Book Chapter
    George, Gavin M.; Ruckle, Michael E.; Abt, Melanie R.; et al. (2018)
    Ascorbic Acid in Plant Growth, Development and Stress Tolerance
  • FLOWERING LOCUS T Triggers Early and Fertile Flowering in Glasshouse Cassava (Manihot esculenta Crantz)
    Item type: Other Journal Item
    Bull, Simon; Alder, Adrian; Barsan, Cristina; et al. (2017)
    Plants
    Accelerated breeding of plant species has the potential to help challenge environmental and biochemical cues to support global crop security. We demonstrate the over-expression of Arabidopsis FLOWERING LOCUS T in Agrobacterium-mediated transformed cassava (Manihot esculenta Crantz; cultivar 60444) to trigger early flowering in glasshouse-grown plants. An event seldom seen in a glasshouse environment, precocious flowering and mature inflorescence were obtained within 4–5 months from planting of stem cuttings. Manual pollination using pistillate and staminate flowers from clonal propagants gave rise to viable seeds that germinated into morphologically typical progeny. This strategy comes at a time when accelerated crop breeding is of increasing importance to complement progressive genome editing techniques.
  • Association of a Disease Complex Involving a Begomovirus, DNA 1 and a Distinct DNA Beta with Leaf Curl Disease of Okra in Pakistan
    Item type: Journal Article
    Mansoor, Shahid; Amin, Imran; Hussain, Mazhar; et al. (2001)
    Plant Disease
  • Pumpkin yellow vein mosaic virus: a novel begomovirus infecting cucurbits
    Item type: Other Journal Item
    Maruthi, Midatharahally N.; Colvin, John; Briddon, Rob W.; et al. (2003)
    Journal of Plant Pathology
  • Diversity of begomoviruses associated with mosaic disease of cultivated cassava (Manihot esculenta Crantz) and its wild relative (Manihot glaziovii Müll. Arg.) in Uganda
    Item type: Journal Article
    Sserubombwe, William S.; Briddon, Rob W.; Baguma, Yona K.; et al. (2008)
    Journal of General Virology
    Cassava (Manihot esculenta) growing in Uganda during 2001–2002 has been screened for the presence of begomoviruses using PCR-RFLP, cloning full-length genomic components and nucleotide sequence analysis. In contrast with a recent survey in neighbouring Kenya, which identified three distinct strains of East African cassava mosaic virus (EACMV, EACMV-UG and EACMV-KE2) as well as East African cassava mosaic Zanzibar virus and the new species East African cassava mosaic Kenya virus, only EACMV-UG and, to a lesser extent, African cassava mosaic virus (ACMV) were found associated with cassava in Uganda. The integrity of the cloned genomic components of representative virus isolates was confirmed by demonstrating their infectivity in Nicotiana benthamiana and cassava using biolistic inoculation, providing a convenient means to screen cassava varieties for disease resistance. Both EACMV-UG and ACMV were also associated with Manihot glaziovii. Infectivity studies using cloned components confirmed that viruses from one host could infect the other, suggesting that this wild relative of cassava might be a reservoir host for the disease. The relatively low level of diversity of begomoviruses associated with cassava mosaic disease in Uganda is consistent with reports that EACMV-UG has displaced other begomovirus species and strains during the recent epidemic that swept through the country.
  • Cassava (Manihot esculenta Crantz)
    Item type: Book Chapter
    Bull, Simon (2015)
    Methods in Molecular Biology ~ Agrobacterium Protocols: Volume 2
    Genetic transformation of plants is an indispensable technique used for fundamental research and crop improvement. Recent advances in cassava (Manihot esculenta Crantz) transformation have facilitated the effective generation of stably transformed cassava plants with favorable traits. Agrobacterium-mediated transformation of friable, embryogenic callus has evolved to become the most widely used approach and has been adopted by research laboratories in Africa. This procedure utilizes axillary meristem tissue (buds) to produce primary and secondary somatic embryos and subsequently friable, embryogenic callus. Agrobacterium harboring a binary expression cassette is used to transform this tissue, which is regenerated via cotyledons and shoot organogenesis to produce rooted in vitro plantlets. This chapter details each step of the procedure using the model cultivar 60444 and provides supplementary notes to successfully produce transgenic cassava.
  • Infectivity, pseudorecombination and mutagenesis of Kenyan cassava mosaic begomoviruses
    Item type: Journal Article
    Bull, Simon; Briddon, Rob W.; Sserubombwe, William S.; et al. (2007)
    Journal of General Virology
    Cloned DNA-A and DNA-B components of Kenyan isolates of East African cassava mosaic virus (EACMV, EACMV-UG and EACMV-KE2), East African cassava mosaic Kenya virus (EACMKV) and East African cassava mosaic Zanzibar virus (EACMZV) are shown to be infectious in cassava. EACMV and EACMKV genomic components have the same iteron sequence (GGGGG) and can form viable pseudorecombinants, while EACMZV components have a different sequence (GGAGA) and are incompatible with EACMV and EACMKV. Mutagenesis of EACMZV has demonstrated that open reading frames (ORFs) AV1 (encoding the coat protein), AV2 and AC4 are not essential for a symptomatic infection of cassava, although mutants of both ORF AV1 and AV2 produce attenuated symptoms in this host. Furthermore, ORF AV1 and AV2 mutants were compromised for coat protein production, suggesting a close structural and/or functional relationship between these coding regions or their protein products.
Publications 1 - 10 of 30