Biology subjects

Spiegelman, Z.

Publications and source records attributed to Spiegelman, Z..

7 recordsLinked to original sources

bioRxiv2026

Convergent recognition of tobamovirus movement proteins by phylogenetically distinct NLR immune receptors

The tobamovirus Tomato brown rugose fruit virus (ToBRFV) has rapidly emerged as a major threat to tomato production worldwide, overcoming the widely deployed Tm-22-mediated resistance and challenging current strategies for tobamovirus disease control. The tomato coiled-coil nucleotide-binding leucine-rich repeat (CC-NLR) immune receptor HREZ confers resistance to ToBRFV. However, the activation mechanism underlying HREZ recognition of ToBRFV remains unclear. Here, we show that HREZ is activated by the movement protein (MP) of ToBRFV and induces hypersensitive cell death. Upon activation, HREZ assembles into a higher-order oligomeric complex, with AlphaFold 3 modelling supporting a pentameric resistosome model. Phylogenetic analysis places HREZ in a CC-NLR lineage distinct from the canonical tobamovirus resistance receptor Tm-22, consistent with convergent evolution of tobamovirus MP recognition. Comparative analysis of eight MPs from the family Virgaviridae reveals that HREZ and Tm-22 have distinct recognition spectra. Four distinct tobamovirus MPs that activate HREZ also promote its assembly into a higher-order oligomeric complex. Together, these findings show how phylogenetically distinct CC-NLRs can converge on the same viral target while retaining distinct recognition breadth and provide a foundation for developing resistance strategies against current and emerging tobamoviruses.

plant biology↗

bioRxiv2026

Antagonism between salicylic acid and auxin responses directs root development during Tobamovirus infection

Viral symptoms in plants are structural and physiological changes resulting from virus-induced manipulation of host pathways. While the effects of viruses on above-ground organs have been well-documented, their impact on the root system remains largely understudied. In tomato (Solanum lycopersicum), the emerging tomato brown rugose fruit virus (ToBRFV; Genus: Tobamovirus) causes significant reductions in root branching. However, the mechanisms underlying this symptom remained unexplored. Here, we provide evidence that tobamovirus-mediated suppression of root branching is conserved between ToBRFV and tomato mosaic virus (ToMV), with ToMV exhibiting a more severe effect over root development. Transcriptome analysis of tobamovirus-infected roots revealed a major shift from growth to defense, marked by the early activation of salicylic acid (SA) signaling. Conversely, auxin signaling was extensively reprogrammed; For example, auxin signaling suppressors such as Aux/IAAs were activated while expression of auxin response factors (ARFs), was downregulated. Importantly, SlARF19a showed reduced expression during infection. Functional analysis of Slarf19a mutants confirmed its critical role in root branching and the root's developmental response to ToMV. We conclude that tobamovirus-mediated root suppression involves an inverse relationship between SA-mediated defense and auxin-mediated growth and identify SlARF19a as a key regulator in this developmental trade-off.

plant biology↗

bioRxiv2024

Rapid, direct, and sequence-specific identification of RNA viruses in various crop plants using CRISPR/Cas13a

Plant viruses are destructive pathogens causing significant damage to various crop species. Rapid, sensitive, and specific detection is crucial for the effective containment of emerging and resistance-breaking viruses. CRISPR/Cas has been established as a useful tool for plant virus identification. However, its application for on-site, direct detection of viruses from plant tissues is still limited. In this study, we present a rapid method for detecting viruses directly from RNA of different crop species using CRISPR/Cas13a. We successfully applied this method to identify tomato brown rugose fruit virus (ToBRFV) in infected tomato plants and differentiate it from closely related tobamoviruses. ToBRFV could be identified in a 100-fold dilution and early during infection, prior to the onset of viral symptoms. Moreover, CRISPR/Cas13a was used to directly identify cucumber green mottle mosaic virus (CGMMV) in cucumber plants and turnip mosaic virus (TuMV) in Brassica napus plants. Finally, we developed a user-friendly, extraction-free, 15-minute protocol for on-site ToBRFV identification using a portable fluorescent viewer and a mobile phone camera. This protocol was successfully applied for ToBRFV detection in a commercial greenhouse. These results demonstrate that CRISPR/Cas13a is a robust technology for direct, rapid, sensitive, and specific identification of multiple viruses in different crop plants that can be easily implemented for on-site detection.

plant biology↗

bioRxiv2023

Restriction of intercellular communication is required for organ regeneration

The excision of the root tip, including the stem cell niche, triggers rapid regeneration from remnant cells in the stump. In plants, cell identity relies on positional information transported through cytoplasmatic bridges known as plasmodesmata. However, how such information is reset to allow the regeneration of lost identities is unknown. Here, we show that the movement of mobile signals is temporarily restricted near the incision site and that regeneration-induced members of the LATERAL ORGAN DOMAIN (LBD) plant-specific developmental regulators are necessary and sufficient for this restriction. Regeneration was disrupted in high-order lbd mutants but was restored by transient localized plasmodesmata closure. We propose that LBD-mediated modulation of intercellular connectivity is crucial for plant regeneration and may have widespread roles in de novo pattern formation. One Sentence SummaryPlant-specific DNA binding genes mediate a transient restriction of intercellular communication to allow root regeneration

plant biology↗

bioRxiv2022

Tm-22 resistance targets a conserved cysteine essential for tobacco mosaic virus (TMV) movement

The tomato Tm-22 gene was considered one of the most durable resistance genes in agriculture, protecting against viruses of the Tobamovirus genus, such as Tomato mosaic virus (ToMV) and Tobacco mosaic virus (TMV). However, an emerging tobamovirus, Tomato brown rugose fruit virus (ToBRFV), has overcome Tm-22, damaging tomato production worldwide. Tm-22 encodes a nucleotide-binding leucine-rich repeat (NLR) class immune receptor that recognizes its effector, the tobamovirus movement protein (MP). Previously, we found that ToBRFV MP (MPToBRFV) enabled the virus to overcome Tm-22- mediated resistance. Yet, it was unknown how Tm-22 remained durable against other tobamoviruses, such as TMV and ToMV, for over 60 years. Here, we show that the presence of a conserved cysteine (C68) in the MP of TMV (MPTMV) is both sufficient to trigger Tm-22 resistance and essential for viral movement. Substitution of MPToBRFV amino acid H67 with the corresponding amino acid in MPTMV (C68) activated Tm-22-medited resistance. However, replacement of C68 in TMV and ToMV disabled the infectivity of both viruses. Phylogenetic and structural prediction analysis revealed that C68 is conserved among all Solanaceae-infecting tobamoviruses except ToBRFV, and localizes to a predicted jelly-roll fold common to various MPs. Cell-to-cell, and subcellular movement analysis showed that C68 is required for the movement of TMV, by regulating the MP interaction with the endoplasmic reticulum and targeting it to plasmodesmata. The dual role of C68 in viral movement and Tm-22 immune activation could explain how TMV was unable to overcome this resistance for such a long period.

plant biology↗

bioRxiv2021

Differential detection of Tomato mosaic virus (ToMV) and Tomato brown rugose fruit virus (ToBRFV) using CRISPR-Cas12

CRISPR/Cas12-based detection is a novel approach for efficient, sequence-specific identification of viruses. Here we adopt the use of CRISPR/Cas12a to identify the Tomato brown rugose fruit virus (ToBRFV), a new and emerging Tobamovirus causing substantial damage to the global tomato industry. Specific guide RNAs (gRNAs) were designed to detect either ToBRFV or the closely related Tomato mosaic virus (ToMV). This technology enabled the differential detection of ToBRFV and ToMV. Sensitivity assays revealed that viruses can be detected from 15-30 ng of RT-PCR product, and that specific detection could be achieved from a mix of ToMV and ToBRFV. In addition, we show that this method enabled the identification of ToBRFV in samples collected from commercial greenhouses. These results demonstrate a new method for species-specific detection of plant viruses. This could provide a platform for the development of efficient and user-friendly ways to distinguish between closely related strains and resistance-breaking pathogens.

molecular biology↗

bioRxiv2020

The Tomato brown rugose fruit virus movement protein overcomes Tm-22 resistance while attenuating viral transport

Tomato brown rugose fruit virus (ToBRFV) is a new virus of the Tobamovirus genus, causing substantial damage to tomato crops in the Middle East. Reports of recent ToBRFV outbreaks from around the world indicate an emerging global epidemic. ToBRFV overcomes all tobamovirus resistances in tomato, including the durable Tm-22 resistance gene. Here, we show that the ToBRFV movement protein (MPToBRFV) is the cause for overcoming Tm-22 resistance. Transient expression of MPToBRFV failed to activate the Tm-22 resistance response. Replacement of the original MP sequences of Tomato mosaic virus (ToMV) with MPToBRFV enabled this recombinant virus to overcome Tm-22 resistance. Hybrid protein analysis revealed that the resistance-breaking elements are located between MPToBRFV amino acids 1 and 216, and not the C terminus as previously assumed. Interestingly, replacement of Tobacco mosaic virus (TMV) and ToMV MPs with MPToBRFV caused an attenuation of systemic infection of both viruses. Cell-to-cell movement analysis revealed that MPToBRFV moves less effectively compared to the TMV MP (MPTMV). These findings suggest that overcoming Tm-22 is associated with attenuated MP function. This viral fitness cost may explain the high durability of Tm-22 resistance, which had remained unbroken for over 60 years.

plant biology↗