Biology subjects

Belausov, E.

Publications and source records attributed to Belausov, E..

11 recordsLinked to original sources

bioRxiv2026

Tomato brown rugose fruit virus and pepino mosaic virus differentially modulate disease severity of bacterial pith necrosis and bacterial canker in tomato

Tomato worldwide production is increasingly challenged by complex disease outbreaks involving multiple interacting pathogens. In Israel, recent years have seen a marked rise in vascular collapse symptoms in greenhouse-grown tomatoes, coinciding with the widespread emergence of tomato brown rugose fruit virus (ToBRFV) and pepino mosaic virus (PepMV). Here, we investigated the bacterial and viral agents associated with these outbreaks and examined how viral infection influences the development and severity of bacterial diseases that cause vascular collapse. Surveys conducted between 2021 and 2026 revealed that tomato pith necrosis outbreaks were associated with a diverse bacterial community dominated by members of the Pseudomonadales and Enterobacterales, while bacterial canker outbreaks were exclusively linked to Clavibacter michiganensis. Multilocus sequence analysis showed that pith necrosis-associated Pseudomonas isolates clustered primarily within the P. syringae, and P. corrugata phylogroups. Pathogenicity assays demonstrated that only a subset of pith necrosis-associated bacteria, P. mediterranea, P. capsici, P. viridiflava, and Xanthomonas euvesicatoria pv. perforans, induced pith necrosis under controlled conditions, with high variability in symptom severity. Co-inoculation experiments showed that ToBRFV- and PepMV-infected plants exhibited a 40-100% increase in lesion size following inoculation with pith necrosis-associated bacteria, without a corresponding increase in bacterial colonization, whereas the same viral infections attenuated wilt symptoms caused by C. michiganensis. Together, our findings demonstrate that endemic viral infections differentially modulate bacterial disease outcomes, either exacerbating or attenuating symptoms depending on the pathogen. These results highlight the importance of multi-pathogen interactions in disease severity and have important implications for tomato disease management.

plant biology↗

bioRxiv2026

Dual Knockout of StAMY23 and StVINV Improves Postharvest Storage Traits in Potato

Starch is the primary carbohydrate reserve in potato (Solanum tuberosum L.) tubers and a critical determinant of their industrial value. The rate of starch degradation during postharvest storage directly influences key traits such as endodormancy (ED) duration and cold-induced sweetening (CIS), which affect sprouting behavior. In this study, we used CRISPR/Cas9 genome editing to knockout StAMY23, a gene encoding -amylase involved in starch breakdown. stamy23 plants exhibited higher yield and extended tuber ED postharvest, without significantly altering CIS or starch granule content. To further reduce CIS, we knockout StAMY23 in VACUOLAR INVERTASE knockout (stvinv) backgrounds, generating stamy23/stvinv double-knockouts plants. These lines showed significantly reduced CIS, prolonged ED, and elevated starch content, along with altered starch granule content. Collectively, our findings demonstrate that simultaneous downregulation of StAMY23 and StVINV can additively enhance desirable postharvest traits, providing a promising strategy for improving potato storage quality through precision genome editing.

plant biology↗

bioRxiv2025

Tissue-Specific Experimental Evolution Reveals Adaptive Trade-Offs in the Plant Vascular Pathogen Clavibacter michiganensis

The plant pathogenic bacterium Clavibacter michiganensis (Cm) is a systemic vascular pathogen that colonizes both xylem vessels and the intracellular apoplast during different stages of infection. To identify traits and loci associated with adaptation to these distinct host microenvironments, we conducted tissue-specific experimental evolution. Twenty independent Cm lineages were repeatedly passaged in either tomato stems or leaves to promote adaptation to vascular or apoplastic lifestyles, respectively. After fifteen passages, adapted clones were characterized for virulence and virulence-related traits. These characterizations demonstrated clear differential associations of virulence-associated traits with the adapted tissue. The majority of vascular-adapted clones displayed enhanced surface attachment, reduced cellulase activity, reduced exopolysaccharide (EPS) production, and attenuated virulence on tomato compared to the parent clone. On the other hand, apoplast-adapted clones displayed reduced biofilm formation and enhanced EPS production while maintaining their virulence on tomato. Whole-genome sequencing of all adapted clones revealed candidate loci linked to tissue adaptation. Notably, six of ten vascular-adapted clones carried two independent mutations in CMM_1284, a putative HipB/XRE-type transcriptional regulator. A CMM_1284 marker exchange mutant displayed phenotypes similar to vascular-adapted clones, suggesting a role for this regulator in vascular colonization. Together, these findings highlight the role of phenotypic plasticity in tissue adaptation of plant pathogens, showing that tissue-specific adaptation involves modulation of surface attachment, EPS production, and cell wall-degrading enzymes. They further reveal a regulated trade-off between vascular persistence, supported by strong surface attachment, and systemic virulence, which depends on bacterial dispersal and migration.

microbiology↗

bioRxiv2025

Deciphering the Survival Strategies of the Entomopathogenic Nematode Steinernema carpocapsae Using Rapid Desiccation Assisted by Nanoparticle-Based Emulsion

Water retention is essential for survival under desiccating conditions, especially for entomopathogenic nematodes (EPNs) used as biocontrol agents. Foliar application of EPNs causes rapid desiccation (RD), severely reducing their survival and efficacy. We investigated the physiological and molecular responses of Steinernema carpocapsae to RD, delivered in a novel nanoparticle-stabilized emulsion to improve tolerance under variable humidity. We hypothesized that the formulation would enhance EPNs survival, by promoting early stress-responsive pathways and water-retention mechanisms. Formulated nematodes exhibited delayed water loss and increased survival under low humidity compared with non-formulated controls. The emulsion mitigated RD by enhanced hydration retention and reduced water loss, effects that were strongly associated with differential trehalose accumulation. In addition, maintenance of basement membrane integrity and cytoskeletal organization, emerged as a critical component of desiccation. These findings advance understanding of RD tolerance in EPNs and demonstrate how tailored formulation strategies can protect biocontrol agents under desiccation stress.

developmental biology↗

bioRxiv2025

ELIP is preferentially expressed in stomatal guard cells and has a role in stomatal opening upon transition to light

Plant early light-induced proteins (ELIPs) are chlorophyll-binding thylakoid membrane proteins commonly believed to function in photoprotection. However, results of studies with mutants or transgenic plants have been contradictory regarding this function, and the mechanistic workings of ELIPs have mostly remained elusive. We studied: (1) ELIP function in tomato (Solanum lycoperiscum) by generation and photosynthetic/physiological characterization of slelip mutants under various light conditions; and (2) ELIP tissue/cell localization by monitoring expression of the Venus yellow fluorescent protein fused to the native SlELIP1 promoter ( pSlELIP1::Venus) in transgenic tomato. Notably, slelip mutants did not display compromised photosynthetic performance and were not more sensitive to photoinhibition compared to parental plants, even following direct sunlight exposure. Surprisingly, pSlELIP1::Venus fusions revealed preferential expression in the leaf epidermis and specifically in stomatal guard cells, with no apparent expression in the mesophyll. No major alterations were observed in leaf gas exchange in slelip mutants at different light conditions. Intriguingly, stomatal conductance was reduced in slelip mutants upon the transition from dark to light. We propose an alternative hypothesis for plant ELIPs as players in the response of guard cells to light, connecting chlorophyll to stomatal function, and presenting a novel research direction for these enigmatic proteins.

plant biology↗

bioRxiv2024

The Calmodulin-like proteins, CML13 and CML14 Function as Myosin Light Chains for the Class XI Myosins in Arabidopsis

Myosins are a crucial motor protein associated with the actin cytoskeleton in eukaryotic cells. Structurally, myosins form heteromeric complexes, with smaller light chains such as calmodulin (CaM) bound to isoleucine-glutamine (IQ) domains in the neck region. These interactions facilitate mechano-enzymatic activity. Recently, we identified Arabidopsis CaM-like (CML) proteins CML13 and CML14 as interactors with proteins containing multiple IQ domains, that function as the myosin VIII light chains. This study demonstrates that CaM, CML13, and CML14 specifically bind to the neck region of all 13 Arabidopsis myosin XI isoforms, with some preference among the CaM/CML-IQ domains. Additionally, we observed distinct residue preferences within the IQ domains for CML13, CML14, and CaM. In vitro experiments revealed that recombinant CaM, CML13, and CML14 exhibit calcium-independent binding to the IQ domains of myosin XIs. Furthermore, when co-expressed with MAP65-1-myosin fusion proteins containing the IQ domains of myosin XIs, CaM, CML13, and CML14 co-localize to microtubules. In vitro actin motility assays demonstrated that recombinant CML13, CML14, and CaM function as myosin XI light chains. A cml13 T-DNA mutant exhibited a shortened primary root phenotype that was complemented by the wild-type CML13 and was similar to that observed in a triple myosin XI mutant (xi3KO). Overall, our data indicate that Arabidopsis CML13 and CML14 are novel myosin XI light chains that likely participate in a breadth of myosin XI functions. HighlightMyosin XI proteins play a crucial role in the plant cytoskeleton, but their associated light chains have remained unidentified. Here, we show that calmodulin-like proteins, CML13 and CML14, serve as light chains for myosin XI, similar to their role for myosin VIII proteins

plant biology↗

bioRxiv2024

A dynamic WUSCHEL / Layer 1 interplay directs shoot apical meristem formation during regeneration

De novo shoot apical meristem (SAM) organogenesis during regeneration in tissue culture has been investigated for several decades, but the precise mechanisms governing early-stage cell fate specification remain elusive. In contrast to SAM establishment during embryogenesis, in vitro SAM formation occurs without positional cues, and is characterized by spontaneous cellular patterning. Here, we have elucidated the initial stages of SAM organogenesis and the molecular mechanisms that orchestrate gene patterning to establish SAM homeostasis. We found that SAM organogenesis in tobacco calli initiates with protuberance formation followed by the formation of an intact L1 layer covering the nascent protuberance. Acquisition of L1 cellular identity is indispensable for de novo SAM formation, which also requires WUSCHEL (WUS) and the cellular capacity to direct anticlinal cell divisions. An intriguing finding is that TONNEAU1 silencing prevents the exclusive occurrence of anticlinal divisions in the outermost layer of the protuberances and suppresses the acquisition of L1 cellular identity, ultimately impeding regeneration. This study exposes an intricate interplay between L1 and WUS expression and that any disruption in this interplay compromises shoot formation. It further provides a novel molecular framework for the characterization of WUS/L1 interplay-mediated shoot apical meristem formation during regeneration.

plant biology↗

bioRxiv2023

Functional Characterization of Calmodulin-like Proteins, CML13 and CML14, as Novel Light Chains of Arabidopsis Class VIII Myosins

Myosins are important motor proteins that associate with the actin cytoskeleton. Structurally, myosins function as heteromeric complexes where smaller light chains, such as calmodulin (CaM), bind to isoleucine-glutamine (IQ) domains in the neck regions to facilitate mechano-enzymatic activity. We recently identified Arabidopsis CaM-like (CML) proteins, CML13 and CML14 as interactors of proteins containing multiple IQ domains, including a member of the myosin VIII class. Here, using in vivo and in vitro assays we demonstrate that CaM, CML13, and CML14 bind the neck region of all four Arabidopsis myosin VIII isoforms. Among ten CML isoforms tested for in planta binding to myosins VIIIs, CaM, CML13, and CML14 gave the strongest signals using in planta split-luciferase protein-interaction assays. In vitro, recombinant CaM, CML13, and CML14 showed specific, high-affinity, calcium-independent binding to the IQ domains of myosin VIIIs. Subcellular localization analysis indicated that CaM, CML13, and CML14 co-localized to plasma membrane-bound puncta when co-expressed with RFP-myosin fusion proteins containing IQ- and tail-domains of myosin VIIIs. In addition, in vitro actin-motility assays using recombinant myosin holoenzymes demonstrated that CaM, CML13, and CML14 function as light chains for myosin VIIIs. Collectively, our data indicate that Arabidopsis CML13 and CML14 are novel myosin VIII light chains. HighlightMyosins are key proteins in the plant cytoskeleton, but the identity of their light chain components is unknown. Here, we show that calmodulin-like proteins function as novel myosin light chains.

plant biology↗

bioRxiv2022

CWLP and PRP940 form plasma-membrane nanodomain complexes with aquaporins, interact with PP2A and contribute to dehydration tolerance

The C-type hybrid-proline-rich protein (HyPRP) AtCWLP and its homolog AtPRP940 are referred as cell wall (CW)-plasma-membrane (PM) linker proteins, but little is known about their functions. Here we show that N-terminal proline-rich domains of CWLP and PRP940, containing glycosylated hydroxyproline residues, contact the CW, while their C-terminal 8CM domains function as PM-scaffolds. Both proteins are detected in PM nanodomains (PM-ND) and show co-localization and co-immunoprecipitation with aquaporins PIP2;1 and PIP2;7. Inhibition of actin polymerization by latrunculin B promotes CWLP-endosome appearance, while blocking the actomyosin-based transport by a truncated form of myosin XI-K relaxes lateral boundaries of CWLP-PIP2;1 PD-NDs. Mass spectrometry data indicate that CWLP co-purifies with dynamins implicated in fission of endocytic PD-ND invaginations. Lack of co-localization and co-immunoprecipitation with aquaporin-binding flotillin (FLOT2) indicates that CWLP and PRP940 mark a new distinct type of PM-ND. Yeast two-hybrid and co-immunoprecipitation assays demonstrate that CWLP and PRP940 interact with multiple aquaporins and several protein phosphatase PP2A-B regulatory subunits. By preventing irreversible separation of CW and PM, and likely assisting PP2A-mediated dephosphorylation of aquaporins and closure of their water channels, overexpression of CWLP confers tolerance to plasmolysis, dehydration and freezing in Arabidopsis and to water shortage in potato plants. Summary StatementArabidopsis Hybrid-Proline-Rich Proteins CWLP and PRP940 occur in association with dynamins, recruit PP2A protein phosphatases to aquaporin water channels in plasma-membrane (PM) nanodomains and elevate tolerance to cellular dehydration.

plant biology↗

bioRxiv2021

Sugar units, not chilling units, control endodormancy duration in plants; potato tuber as a case study

Endodormancy (ED) is a crucial stage in the life cycle of many perennial plants, regulated by genetic and environmental factors. Chilling units, growth regulators, and nutrient supply are considered inducers of ED release, but the mechanism governing ED duration is poorly understood. The potato tuber has been used as a model system to study metabolic processes associated with ED release. Cold-induced sweetening is a well-known response of the tuber to chilling. Here, we found that cold stress induces an increase in sugar units in association with plasmodesmatal closure in the dormant bud cells. Tuber sweetening was associated with shortened ED duration after cooling. Heat exposure also caused sugar unit accumulation followed by faster ED release. A logistic function was developed to predict ED duration based on sugar unit measurements. We discovered that ED release is better correlated with the accumulation of sugar units compared to chilling units. CRISPR/Cas9 knockout of the vacuolar invertase gene (StVInv) induced longer ED, but only in cultivars in which the mutation modified the level sugar units. Our results suggest that sugar units are better predictors of vegetative bud ED duration than chilling units.

plant biology↗

bioRxiv2019

Vacuolar processing enzyme translocates to the vacuole through the autophagy pathway to induce programmed cell death

The caspase-like vacuolar processing enzyme (VPE) is a key factor in programmed cell death (PCD) associated with plant stress responses. Growth medium lacking a carbon source and dark conditions caused punctate labeling of 35S::VPE1-GFP (StVPE1-GFP) in potato leaves. Carbon starvation of BY-2 cells induced higher VPE activity and PCD symptoms. Growing VPE-RNAi BY-2 cells without sucrose reduced VPE activity and prevented PCD symptoms. During extended exposure to carbon starvation, VPE expression and activity levels peaked, with a gradual increase in BY-2 cell death. Histological analysis of StVPE1-GFP in BY-2 cells showed that carbon starvation induces its translocation from the endoplasmic reticulum to the central vacuole, through tonoplast engulfment. Exposure of BY-2 culture to the autophagy inhibitor concanamycin A caused autophagic bodies accumulation in the cell vacuole. Such accumulation did not occur in the presence of 3-methyladenine, an inhibitor of early-stage autophagy. BY-2 cells constitutively expressing StATG8IL-RFP, an autophagosome marker, showed colocalization with the StVPE1-GFP protein in the cytoplasm and vacuole. RNAi silencing of the core autophagy component ATG4 in BY-2 cells reduced VPE activity and cell death. These results are the first to suggest that VPE translocates to the cell vacuole through the autophagy pathway, leading to PCD.\n\nOne sentence summaryCarbon starvation induced programmed cell death by trafficking vacuolar processing enzyme through the autophagy pathway to the vacuole.

plant biology↗