This study elucidates a pathway whereby a viral CP protein directly disrupts chlorophyll biosynthesis to induce leaf yellowing and reveals a strategy wherein the virus exploits this symptom as a visual signal to manipulate pollinator behavior, thus creating a ‘symptom-mediated transmission’ loop.
Abstract
Plant viral symptoms are not merely passive consequences of infection but can represent adaptive strategies for enhancing transmission. The molecular mechanisms and ecological consequences of such virus-induced symptoms, particularly in perennial crops such as kiwifruit, require exploration. Here, in field experiments, we discovered a kiwifruit infected with a novel virus, Actinidia yellow ringspot virus (AYRSpV), which exhibits severe yellowing symptoms and significantly increases the attractiveness of pollinating insects such as bees and aphids during the flowering season. Given that AYRSpV is pollen-transmissible, this visual manipulation may facilitate the pollinator-mediated spread of the virus. We further explored whether the AYRSpV coat protein (CP) is a key virulence determinant that interacts with and targets the chlorophyll metabolic enzyme magnesium protoporphyrin IX methyltransferase (ChlM) for degradation, leading to a significant reduction in chlorophyll content and systemic leaf yellowing. Knockout of kiwifruit ChlM recapitulated the yellowing phenotype and further enhanced plant susceptibility to AYRSpV. Our study elucidates a pathway whereby a viral CP protein directly disrupts chlorophyll biosynthesis to induce leaf yellowing. Furthermore, we reveal a strategy wherein the virus exploits this symptom as a visual signal to manipulate pollinator behavior, thus creating a ‘symptom-mediated transmission’ loop. These findings provide a comprehensive understanding of the molecular and ecological mechanisms driving the spread of an emerging kiwifruit virus.
Plants frequently encounter multiple pathogens concurrently, yet the molecular bases of pathogen-pathogen interactions during mixed infections remain largely unresolved. Here we show that co-infection of rice by Rice orange leaf phytoplasma (ROLP) and Rice stripe mosaic virus (RSMV) markedly suppresses RSMV proliferation in both host plants and the insect vector. Electron microscopy and confocal imaging reveal that ROLP and RSMV co-inhabit individual rice phloem cells and undergo close membrane interaction, producing swollen RSMV virions with reduced infectivity. We further demonstrate that the ROLP membrane protein Imp interacts with the RSMV G envelope protein and competitively disrupts the G-M association essential for virion assembly. The Imp region encompassing residues 96-122 (Imp-α4) is necessary for this inhibition. Transgenic rice overexpressing Imp or Imp-α4 phenocopies these effects, displaying deformed virions and diminished viral load. These findings uncover a cross-kingdom antagonistic mechanism between two phylogenetically distant pathogens and offer conceptual directions for engineering durable antiviral resistance.
Jiaxin Qiu, Yu-Jiao Zheng, Yan-Mei Yi et al.· Plant, Cell and Environment· 0 citations
This review emphasizes current knowledge on the biology, symptom modulation, molecular mechanisms, ecological roles, and detection strategies of CMV satRNAs, while highlighting their significance in viral evolution and disease epidemiology.
J. Vinodhini, K. Nagendran, L. Rajendran et al.· Current Microbiology· 0 citations
ABSTRACT Geminiviruses severely threaten global crop production. Tomato yellow leaf curl virus (TYLCV) encodes multifunctional effector C4, which participates in diverse biological processes and interacts with host proteins to facilitate infection. Despite extensive studies on geminiviral C4, how TYLCV C4 suppresses tomato immunity remains poorly characterized. In this study, we identified the tomato 14‐3‐3 protein SlTFT2 as a specific interaction partner of the TYLCV C4 protein. We demonstrated that SlTFT2 functions as a positive regulator of antiviral defence, as its silencing enhanced systemic viral infection, whereas its overexpression restricted infection. A critical serine residue at position 86 in C4 was essential for this interaction, and mutation of this residue (S86A or S86L) in TYLCV infectious clones significantly attenuated viral infectivity. Furthermore, C4, but not the S86A or S86L mutants, reduced the nuclear accumulation of SlTFT2. Collectively, our findings establish that the C4–SlTFT2 interaction is indispensable for TYLCV‐mediated immunosuppression. Moreover, C4 promotes successful TYLCV infection by reducing the nuclear accumulation of SlTFT2 through this interaction, revealing a novel mechanism by which the virus subverts host defence by targeting a 14‐3‐3 protein.
Beet curly top viruses (BCTVs) are highly devastating viral pathogens affecting a wide range of plant species worldwide and are transmitted only by leafhoppers in the genus Circulifer. During viral infection, host plant cells undergo morphological changes known as cytopathic effects (CPEs). This study investigated CPEs induced by BCTVs infecting four plant hosts: tomato, pepper, sugar beet, and hemp. BCTV infection resulted in severe stunting, leaf curling, and yellowing, leading to reduced photosynthetic capacity and yield losses. Transmission electron microscopy of ultrathin leaf sections revealed that chloroplasts were the universal primary target of BCTV damage across all four hosts, consistently exhibiting severe structural disruption, while starch grains and vacuoles were also affected. Notably, host-specific ultrastructural alterations were observed: enlarged chloroplasts with disrupted grana stacks and small stromal vesicles in BCTV-Wor-infected tomato and hemp, swollen chloroplasts with disappeared grana and disorganized thylakoids in BCTV-Svr-infected sugar beet, and unidentifiable grana structures in BCTV-PeYDV-infected pepper. These alterations did not correlate with virus strain, suggesting that host-specific inducible defense mechanisms play a greater role than strain identity. This is the first study to highlight the diverse ultrastructural impacts of BCTVs across plant species, improving understanding of host–virus interactions and aiding development of control strategies to safeguard global food security.
Although tomato mosaic virus (ToMV) is an economically important tobamovirus, the physiological and molecular events occurring during the asymptomatic phase of infection remain poorly understood. In this study, we investigated the early responses of Nicotiana tabacum cv. Samsun to ToMV infection using an integrated physiological, biochemical, photosynthetic, and molecular approach. Viral accumulation was quantified via RT-PCR. Oxidative stress markers, antioxidant systems, photosynthetic performance, and gene expression were analyzed at 7 days post inoculation (DPI), before visible symptoms developed. Although infected plants remained symptomless, ToMV was detected in 80% of inoculated plants. Early infection induced oxidative stress, evidenced by increased malondialdehyde content, reduced free amino acid levels, and enhanced activities of superoxide dismutase and peroxidase. Total glutathione, phenolic compounds, and phenylpropanoids remained unchanged, whereas flavonoid content decreased significantly. ToMV infection also impaired the photosynthetic apparatus, resulting in reduced chlorophyll and carotenoid contents, decreased electron transport efficiency, and increased energy dissipation within photosystem II. Gene expression analysis revealed significant upregulation of defense- and stress-related genes (WRKY1, HSP70, GR, and DHAR), as well as chloroplast-associated genes (psaA and rbcL). Correlation analyses demonstrated coordinated relationships among viral accumulation, oxidative stress, antioxidant responses, and photosynthetic performance. These findings provide new insights into the asymptomatic phase of ToMV infection and identify potential early markers of host responses to viral infection.
Wojciech Makowski, I. Mažeikienė, Łucja Kmita et al.· International Journal of Mol...· 0 citations
This review examines the defence strategies of rice and provides key insights into host-pathogen interactions that inform the development of durable resistance and improved disease management strategies, including integrating molecular breeding with sustainable agricultural practices to mitigate yield losses caused by BLB.
M. Syed, N. Rajinimala, M. Theradimani et al.· Plant Science Today· 0 citations
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