Biology subjects

Teper, D.

Publications and source records attributed to Teper, D..

4 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↗

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↗

bioRxiv2024

Comparative transcriptomic profile reveals candidate genes manipulated by type III effectors of Pantoea agglomerans pv. betae leading to gall formation in beet

Pantoea agglomerans pv. betae (Pab) induces tumor-like galls in beet and gypsophila, a process mediated by the secretion of effector proteins via Pabs type III secretion system (T3SS). The molecular mechanisms underlying Pab-induced gall formation remain largely unexplored. This study delves into the cellular architecture and transcriptional profile of Pab-mediated galls, comparing host responses to wild-type Pab and a T3SS-inactive mutant, hrcC-. Morphological analysis using scanning electron microscopy and cross-sectional visualization of infected beet leaf tissues revealed that Pab-induced gall-like structures are linked to cell hyperplasia and tissue ruptures, contingent on T3SS activity. Comparative transcriptome analysis of wild-type Pab and hrcC- Pab-infected beet leaves at 12 and 48 hours unveiled significant transcriptional reprogramming, with nearly 2,000 differentially expressed genes at 48 hours post inoculation. Enrichment analyses identified the upregulation of pathways related to signal transduction, defense, carbohydrate metabolism, and cell wall modulation in wild-type Pab-infected leaves compared to controls. Particularly notable was the significant upregulation of numerous genes associated with cell wall loosening by wild-type Pab, suggesting an initial rearrangement of cell wall architecture facilitates gall formation. Furthermore, transcriptome analysis demonstrated that wild-type Pab suppresses the expression of the betalain biosynthetic gene DOPA 4,5-DIOXYGENASE, leading to reduced betalain accumulation in infected tissues compared to the mutant strain. These findings offer fresh insights into the transcriptional and physiological manipulation of host tissue during the early stages of Pab-induced gall formation.

plant biology↗

bioRxiv2023

Allelic variations in a serine protease effector within Clavibacter michiganensis populations determine pathogen host range

Plant pathogenic bacteria often have a narrow host range, which can vary among different isolates within a population. Here we investigated the host range of the tomato pathogen Clavibacter michiganensis (Cm). We determined the genome sequences of 40 tomato Cm isolates and screened them for pathogenicity on tomato and eggplant. Our screen revealed that out of the tested isolates, five were unable to cause disease on any of the hosts, 33 were exclusively pathogenic on tomato, and two were capable of infecting both tomato and eggplant. Through comparative genomic analyses, we identified that the five non-pathogenic isolates lacked the chp/tomA pathogenicity island, which has previously been associated with virulence in tomato. In addition, we found that the two eggplant-pathogenic isolates encode a unique allelic variant of the serine protease chpG (chpGC), an effector that is recognized in eggplant. Introduction of chpGC into a chpG inactivation mutant in the eggplant-non-pathogenic strain Cm101, failed to complement the mutant, which retained its ability to cause disease in eggplant and failed to elicit hypersensitive response (HR). Conversely, introduction of the chpG variant from Cm101 into an eggplant pathogenic isolate (CmC48), eliminated its pathogenicity on eggplant, and enabled CmC48 to elicit HR. Our study demonstrates that allelic variation in the chpG effector gene is a key determinant of host range plasticity within Cm populations.

microbiology↗