Lesley Torrance - Academia.edu (original) (raw)

Papers by Lesley Torrance

Food and Energy Security, Mar 15, 2022

This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Barley stripe mosaic (BSMV) and potato mop-top virus (PMTV) genomes contain modules of three over... more Barley stripe mosaic (BSMV) and potato mop-top virus (PMTV) genomes contain modules of three overlapping genes called the triple gene block (TGB) of the hordeivirus type. The TGB proteins are essential for movement. In addition, BSMV encodes a multifunctional, cysteine rich protein called γB that has RNA silencing suppression and pathogenicity enhancing activities.

Journal of Plant Physiology

Journal of Virological Methods, May 1, 2023

Potato and sweetpotato in Africa: transforming the value chains for food and nutrition security

Q Open

Foresight and trade-off analyses offer organizations such as CGIAR an opportunity to better prepa... more Foresight and trade-off analyses offer organizations such as CGIAR an opportunity to better prepare for alternative futures through adaptive research strategy and management. This essay introduces a set of papers that explore foresight and trade-off analyses within the context of the major reforms now occurring in the CGIAR. We tease out lessons not only for One CGIAR, but also for international development research organizations more broadly.

Plant physiology, Mar 26, 2018

Virus entry to the vascular system is a vital process in the initiation of a systemic infection. ... more Virus entry to the vascular system is a vital process in the initiation of a systemic infection. Virus movement proteins (MP) are key to this and the potato mop-top virus (PMTV) MP, TGB1, is involved in long distance movement of both viral ribonucleoprotein complexes and virions. Analysis of TGB1 interactions with host Nicotiana benthamiana proteins revealed a novel interaction with a member of the heavy metal associated isoprenylated plant protein family, HIPP26, thought to act as a plasma membrane to nucleus abiotic stress signalling relay. NbHIPP26 promoter-reporter fusions revealed vascular tissue specific expression with NbHIPP26 gene expression being upregulated by drought and PMTV infection. In addition, PMTV infection protected plants from drought. Knock down of NbHIPP26 expression inhibited virus long distance movement but did not affect cell-to-cell movement. NbHIPP26 localised at the plasma membrane and plasmodesmata. Mutational and biochemical analysis indicated that thi...

Plant Pathology, 2015

Seed potato degeneration, the reduction in yield or quality caused by an accumulation of pathogen... more Seed potato degeneration, the reduction in yield or quality caused by an accumulation of pathogens and pests in planting material due to successive cycles of vegetative propagation, has been a long-standing production challenge for potato growers around the world. In developed countries this problem has been overcome by general access to and frequent use of seed, produced by specialized growers, that has been certified to have pathogen and pest incidence below established thresholds, often referred to as certified seed. The success of certified seed in developed countries has concentrated the research and development agenda on the establishment of similar systems in developing countries. Despite these efforts, certified seed has had little penetration into the informal seed systems currently in place in most developing countries. Small-scale farmers in these countries continue to plant seed tubers acquired through the informal seed system, i.e. produced on-farm or acquired from neighbours or local markets. Informal seed tubers frequently have poor health status, leading to significant reductions in yield and/or market value. This review emphasizes the need to refocus management efforts in developing countries on improving the health status of seed tubers in the informal system by integrating disease resistance and on-farm management tools with strategic seed replacement. This 'integrated seed health strategy' can also prolong the good health status of plants derived from certified seed, which would otherwise be diminished due to potential rapid infection from neighbouring fields. Knowledge gaps, development challenges and impacts of this integrated seed health strategy are discussed.

Advances in Applied Microbiology, Vol 81, 2012

Most reviews of climate change are epidemiological, focusing on impact assessment and risk mappin... more Most reviews of climate change are epidemiological, focusing on impact assessment and risk mapping. However, there are many reports of the effects of environmental stress factors on defense mechanisms in plants against pathogens. We review those representative of key climate change-related stresses to determine whether there are any patterns or trends in adaptation responses. We recognize the complexity of climate change itself and the multitrophic nature of the complex biological interactions of plants, microbes, soil, and the environment and, therefore, the difficulty of reductionist dissection approaches to resolving the problems. We review host defense genes, germplasm, and environmental interactions in different types of organisms but find no significant group-specific trends. Similarly, we review by host defense mechanism type and by host-pathogen trophic relationship but identify no dominating mechanism for stress response. However, we do identify core stress response mechanisms playing key roles in multiple response pathways whether to biotic or abiotic stress. We suggest that these should be central to mechanistic climate change plant defense research. We also recognize biodiversity, heterogeneity, and the need for understanding stress in a true systems biology approach as being essential components of progressing our understanding of and response to climate change.

The potato mop-top virus (PMTV) triple gene block 2 (TGB2) movement proteins fused to monomeric r... more The potato mop-top virus (PMTV) triple gene block 2 (TGB2) movement proteins fused to monomeric red fluorescent protein (mRFP-TGB2) was expressed under the control of the PMTV subgenomic promoter from a PMTV vector. The subcellular localizations and interactions of mRFP-TGB2 were investigated using confocal imaging [confocal laser-scanning microscope, (CLSM)] and biochemical analysis. The results revealed associations with membranes of the endoplasmic reticulum (ER), mobile granules, small round structures (1-2 μm in diameter), and chloroplasts. Expression of mRFP-TGB2 in epidermal cells enabled cell-to-cell movement of a TGB2 defective PMTV reporter clone, indicating that the mRFP-TGB2 fusion protein was functional and required for cell-to-cell movement. Protein-lipid interaction assays revealed an association between TGB2 and lipids present in chloroplasts, consistent with microscopical observations where the plastid envelope was labeled later in infection. To further investigate the association of PMTV infection with chloroplasts, ultrastructural studies of thin sections of PMTV-infected potato and Nicotiana benthamiana leaves by electron microscopy revealed abnormal chloroplasts with cytoplasmic inclusions and terminal projections. Viral coat protein (CP), genomic RNA and fluorescently-labeled TGB2 were detected in plastid preparations isolated from the infected leaves, and viral RNA was localized to chloroplasts in infected tissues. The results reveal a novel association of TGB2 and vRNA with chloroplasts, and suggest viral replication is associated with chloroplast membranes, and that TGB2 plays a novel role in targeting the virus to chloroplasts.

PLoS ONE, 2013

A tightly-focused ultrashort pulsed laser beam incident upon a cell membrane has previously been ... more A tightly-focused ultrashort pulsed laser beam incident upon a cell membrane has previously been shown to transiently increase cell membrane permeability while maintaining the viability of the cell, a technique known as photoporation. This permeability can be used to aid the passage of membrane-impermeable biologically-relevant substances such as dyes, proteins and nucleic acids into the cell. Ultrashort-pulsed lasers have proven to be indispensable for photoporating mammalian cells but they have rarely been applied to plant cells due to their larger sizes and rigid and thick cell walls, which significantly hinders the intracellular delivery of exogenous substances. Here we demonstrate and quantify femtosecond optical injection of membrane impermeable dyes into intact BY-2 tobacco plant cells growing in culture, investigating both optical and biological parameters. Specifically, we show that the long axial extent of a propagation invariant (''diffractionfree'') Bessel beam, which relaxes the requirements for tight focusing on the cell membrane, outperforms a standard Gaussian photoporation beam, achieving up to 70% optoinjection efficiency. Studies on the osmotic effects of culture media show that a hypertonic extracellular medium was found to be necessary to reduce turgor pressure and facilitate molecular entry into the cells.

Phytopathology, 1998

Phage-displayed peptides were selected from the Cys 1 random phage display peptide library that b... more Phage-displayed peptides were selected from the Cys 1 random phage display peptide library that bound strongly to the monoclonal antibody (MAb) SCR 20. The binding peptides were fused to the N-terminus of the phage protein pVIII. Preparations of the phage were shown to be effective as controls for the functionality of the SCR 20 MAb in both enzyme-linked immunosorbent assays and dot blot immunoassays. UV irradiation that eliminated phage infectivity did not greatly alter the antigenicity. Peptides displayed on phage are quick and cheap to prepare, and preparations can be standardized to ensure comparability among different assays. The peptide library approach can be readily extended for use with other MAbs to obtain inexpensive and safe standardized positive control reagents for use in immunoassays to diagnose plant disease.

Molecular Plant-Microbe Interactions, 2010

Several RNA virus genera belonging to the Virgaviridae and Flexiviridae families encode proteins ... more Several RNA virus genera belonging to the Virgaviridae and Flexiviridae families encode proteins organized in a triple gene block (TGB) that facilitate cell-to-cell and long-distance movement. The TGB proteins have been traditionally classified as hordei-like or potex-like based on phylogenetic comparisons and differences in movement mechanisms of the Hordeivirus and Potexvirus spp. However, accumulating data from other model viruses suggests that a revised framework is needed to accommodate the profound differences in protein interactions occurring during infection and ancillary capsid protein requirements for movement. The goal of this article is to highlight common features of the TGB proteins and salient differences in movement properties exhibited by individual viruses encoding these proteins. We discuss common and divergent aspects of the TGB transport machinery, describe putative nucleoprotein movement complexes, highlight recent data on TGB protein interactions and topologic...

Molecular Plant Pathology, 2002

Advances in molecular biology have made it possible to produce antibody fragments comprising the ... more Advances in molecular biology have made it possible to produce antibody fragments comprising the binding domains of antibody molecules in diverse heterologous systems, such as Escherichia coli , insect cells, or plants. Antibody fragments specific for a wide range of antigens, including plant pathogens, have been obtained by cloning V-genes from lymphoid tissue, or by selection from large naive phage display libraries, thus avoiding the need for immunization. The antibody fragments have been expressed as fusion proteins to create different functional molecules, and fully recombinant assays have been devised to detect plant viruses. The defined binding properties and unlimited cheap supply of antibody fusion proteins make them useful components of standardized immunoassays. The expression of antibody fragments in plants was shown to confer resistance to several plant pathogens. However, the antibodies usually only slowed the progress of infection and durable 'plantibody' resistance has yet to be demonstrated. In future, it is anticipated that antibody fragments from large libraries will be essential tools in highthroughput approaches to post-genomics research, such as the assignment of gene function, characterization of spatio-temporal patterns of protein expression, and elucidation of proteinprotein interactions.

Journal of Virology, 2013

Potato mop-top virus (PMTV) produces a defective RNA (D RNA) encompassing the 5′-terminal 479 nuc... more Potato mop-top virus (PMTV) produces a defective RNA (D RNA) encompassing the 5′-terminal 479 nucleotides (nt) and 3′-terminal 372 nt of RNA-TGB (where TGB is triple gene block). The mechanism that controls D RNA biogenesis and the role of D RNA in virus accumulation was investigated by introducing deletions, insertions, and point mutations into the sequences of the open reading frames (ORFs) of TGB1 and the 8-kilodalton (8K) protein that were identified as required for efficient production of the D RNA. Transient expression of RNA-TGB in the absence of RNA-Rep (which encodes the replicase) did not result in accumulation of D RNA, indicating that its production is dependent on PMTV replication. The D RNA could be eliminated by disrupting a predicted minus-strand stem-loop structure comprising complementary sequences of the 5′ TGB1 ORF and the 3′ 8K ORF, suggesting intramolecular template switching during positive-strand synthesis as a mechanism for the D RNA biogenesis. Virus accumu...