| 1. |
- Ghadamgahi, Farideh, et al.
(författare)
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Plant Growth-Promoting Activity of Pseudomonas aeruginosa FG106 and Its Ability to Act as a Biocontrol Agent against Potato, Tomato and Taro Pathogens
- 2022
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Ingår i: Biology. - : MDPI AG. - 2079-7737. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Simple Summary Microbial bio-stimulants are attracting increasing attention in agricultural research. In particular, plant growth-promoting rhizobacteria (PGPR) have great potential to improve crops' productivity and tolerance of biotic and abiotic stresses. It is anticipated that PGPR could eventually replace synthetic fungicides in agriculture. This research evaluated Pseudomonas aeruginosa strain FG106-which was isolated from tomato plants- as a potential biocontrol agent against several plant pathogens. This strain displayed multiple plant growth-promoting attributes and high in vitro and in vivo inhibition of growth and pathogenicity of tested phytopathogens. It is thus a multifunctional PGPR with potential applications as a biocontrol agent to control fungal and bacterial pathogens. P. aeruginosa strain FG106 was isolated from the rhizosphere of tomato plants and identified through morphological analysis, 16S rRNA gene sequencing, and whole-genome sequencing. In vitro and in vivo experiments demonstrated that this strain could control several pathogens on tomato, potato, taro, and strawberry. Volatile and non-volatile metabolites produced by the strain are known to adversely affect the tested pathogens. FG106 showed clear antagonism against Alternaria alternata, Botrytis cinerea, Clavibacter michiganensis subsp. michiganensis, Phytophthora colocasiae, P. infestans, Rhizoctonia solani, and Xanthomonas euvesicatoria pv. perforans. FG106 produced proteases and lipases while also inducing high phosphate solubilization, producing siderophores, ammonia, indole acetic acid (IAA), and hydrogen cyanide (HCN) and forming biofilms that promote plant growth and facilitate biocontrol. Genome mining approaches showed that this strain harbors genes related to biocontrol and growth promotion. These results suggest that this bacterial strain provides good protection against pathogens of several agriculturally important plants via direct and indirect modes of action and could thus be a valuable bio-control agent.
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| 2. |
- Hanifah, Nurul Atilia Shafienaz binti, et al.
(författare)
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Comparative transcriptome profiling provides insights into the growth promotion activity of Pseudomonas fluorescens strain SLU99 in tomato and potato plants
- 2023
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Ingår i: Frontiers in Plant Science. - 1664-462X. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- The use of biocontrol agents with plant growth-promoting activity has emerged as an approach to support sustainable agriculture. During our field evaluation of potato plants treated with biocontrol rhizobacteria, four bacteria were associated with increased plant height. Using two important solanaceous crop plants, tomato and potato, we carried out a comparative analysis of the growth-promoting activity of the four bacterial strains: Pseudomonas fluorescens SLU99, Serratia plymuthica S412, S. rubidaea AV10, and S. rubidaea EV23. Greenhouse and in vitro experiments showed that P. fluorescens SLU99 promoted plant height, biomass accumulation, and yield of potato and tomato plants, while EV23 promoted growth in potato but not in tomato plants. SLU99 induced the expression of plant hormone-related genes in potato and tomato, especially those involved in maintaining homeostasis of auxin, cytokinin, gibberellic acid and ethylene. Our results reveal potential mechanisms underlying the growth promotion and biocontrol effects of these rhizobacteria and suggest which strains may be best deployed for sustainably improving crop yield.
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| 3. |
- Kalyandurg, Pruthvi Balachandra, et al.
(författare)
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Efficient RNA silencing suppression activity of Potato Mop-Top Virus 8K protein is driven by variability and positive selection
- 2019
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Ingår i: Virology. - : Elsevier BV. - 0042-6822 .- 1178-122X. ; 535, s. 111-121
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Tidskriftsartikel (refereegranskat)abstract
- Previously, we investigated the evolution of Potato mop-top virus (PMTV) ORFs. Results indicate that positive selection acts exclusively on an ORF encoding the 8K protein, a weak viral suppressor of RNA silencing (VSR). However, how the extraordinary variability contributes to 8K-mediated RNA silencing suppression remains unknown. Here, we characterized the RNA silencing suppression activity of the 8K protein from seven diverse isolates. We show that 8K encoded by isolate P1 exhibits stronger RNA silencing suppression activity than the 8K protein from six other isolates. Mutational analyses revealed that Ser-50 is critical for these differences. By comparing small RNA profiles we found a lower abundance of siRNAs with U residue at the 5'-terminus after expression of the P1 8K compared to expression of 8K from isolate P125, an isolate with weak VSR activity. These results provide new clues as to the role of positive selection in shaping activities of VSRs.
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| 4. |
- Kalyandurg, Pruthvi Balachandra, et al.
(författare)
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Molecular and pathobiological characterization of 61 Potato mop-top virus full-length cDNAs reveals great variability of the virus in the centre of potato domestication, novel genotypes and evidence for recombination
- 2017
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Ingår i: Molecular Plant Pathology. - : Wiley. - 1464-6722 .- 1364-3703. ; 18, s. 864-877
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Tidskriftsartikel (refereegranskat)abstract
- The evolutionary divergence of Potato mop-top virus (PMTV), a tri-partite, single-stranded RNA virus, is exceptionally low, based on the analysis of sequences obtained from isolates from Europe, Asia and North America. In general, RNA viruses exist as dynamic populations of closely related and recombinant genomes that are subjected to continuous genetic variation. The reason behind the low genetic variation of PMTV remains unclear. The question remains as to whether the low variability is a shared property of all PMTV isolates or is a result of the limited number of isolates characterized so far. We hypothesized that higher divergence of the virus might exist in the Andean regions of South America, the centre of potato domestication. Here, we report high variability of PMTV isolates collected from 12 fields in three locations in the Andean region of Peru. To evaluate PMTV genetic variation in Peru, we generated full-length cDNA clones, which allowed reliable comparative molecular and pathobiological characterization of individual isolates. We found significant divergence of the CP-RT and 8K sequences. The 8K cistron, which encodes a viral suppressor of RNA silencing, was found to be under diversifying selection. Phylogenetic analysis determined that, based on the CP-RT sequence, all PMTV isolates could be categorized into three separate lineages (clades). Moreover, we found evidence for recombination between two clades. Using infectious cDNA clones of the representatives of these two clades, as well as reassortants for the RNA-CP genomic component, we determined the pathobiological differences between the lineages, which we coined as S (for severe) and M (for mild) types. Interestingly, all isolates characterized previously (from Europe, Asia and North America) fall into the S-type clade, whereas most of the Peruvian isolates belong to the M-type. Taken together, our results support the notion of the single introduction of PMTV from the centre of potato origin to Europe, and subsequent spread of the S-type into Asia and USA. This is also supported by the suggested novel classification of isolates based on genetic constellations.
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| 5. |
- Kalyandurg, Pruthvi Balachandra, et al.
(författare)
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Potato Mop-Top Virus Co-Opts the Stress Sensor HIPP26 for Long-Distance Movement
- 2018
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 176, s. 2052-2070
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Tidskriftsartikel (refereegranskat)abstract
- Virus movement proteins facilitate virus entry into the vascular system to initiate systemic infection. The potato mop-top virus (PMTV) movement protein, TGB1, is involved in long-distance movement of both viral ribonucleoprotein complexes and virions. Here, our analysis of TGB1 interactions with host Nicotiana benthamiana proteins revealed an interaction with a member of the heavy metal-associated isoprenylated plant protein family, HIPP26, which acts as a plasma membrane-to-nucleus signal during abiotic stress. We found that knockdown of NbHIPP26 expression inhibited virus long-distance movement but did not affect cell-to-cell movement. Drought and PMTV infection up-regulated NbHIPP26 gene expression, and PMTV infection protected plants from drought. In addition, NbHIPP26 promoter-reporter fusions revealed vascular tissue-specific expression. Mutational and biochemical analyses indicated that NbHIPP26 subcellular localization at the plasma membrane and plasmodesmata was mediated by lipidation (S-acylation and prenylation), as nonlipidated NbHIPP26 was predominantly in the nucleus. Notably, coexpression of NbHIPP26 with TGB1 resulted in a similar nuclear accumulation of NbHIPP26. TGB1 interacted with the carboxyl-terminal CVVM (prenyl) domain of NbHIPP26, and bimolecular fluorescence complementation revealed that the TGB1-HIPP26 complex localized to microtubules and accumulated in the nucleolus, with little signal at the plasma membrane or plasmodesmata. These data support a mechanism where interaction with TGB1 negates or reverses NbHIPP26 lipidation, thus releasing membrane-associated NbHIPP26 and redirecting it via microtubules to the nucleus, thereby activating the drought stress response and facilitating virus long-distance movement.
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| 6. |
- Kalyandurg, Pruthvi Balachandra
(författare)
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Potato mop-top virus: Variability, Movement and Suppression of Host Defence
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Potato mop-top virus (PMTV) causes an economically damaging disease called potato spraing. Despite being reported across the potato growing regions in the world, very little genetic variability has been reported for the virus. Also, the knowledge on how PMTV suppresses host defence mechanism, and how it interacts with the host during the cellto-cell and long-distance movement is still insufficient to develop successful preventive measures against the PMTV infection. This thesis work identified high diversity of the PMTV in the Andean region of Peru compared to the rest of the world. Among the PMTV genome, CP-RT and 8K genomic regions accumulated the largest number of mutations. Through phylogenetic analysis of the RNA-CP segment we identified two prevailing genotypes around the world. Based on the pathobiological differences, we named these lineages as S (severe), and M (mild) types. The phylogenetic relationship determined in this study helped us to propose a novel classification of PMTV isolates. Our analysis to address the selection pressure on the PMTV genome revealed that the ORF encoding the 8K protein, a viral suppressor of RNA silencing (VSR) is under strong positive selection. Characterization of the RNA silencing suppression activity of the 8K protein from seven highly diverse isolates revealed that the 8K encoded by a Peruvian isolate, P1 exhibits stronger RNA silencing suppression activity compared to that of other isolates. Through mutational analysis, we identified that Ser-50 is necessary for these differences. Through deep sequencing for sRNAs, we identified that VSRs reduce the sRNA accumulation. We observed lower amount of siRNAs with U residue at the 5’-terminus suggesting that P1 8K might affect AGO1-mediated RNA silencing. The present work also identified key host factors necessary for the cell-to-cell and long distance movement of the virus. We showed that the actin network and certain class VIII myosins motors are important for the cell-to-cell movement of PMTV. The dependency on the acto-myosin network for PMTV movement was further demonstrated by the fluorescence recovery after photo bleaching experiments that resulted in compromised delivery of the TGB1 at the plasmodesmata upon disrupting actin and inhibiting two class VIII myosins. In contrast, class XI myosins did not have a significant effect on the cell-to-cell movement of the PMTV, although they appear to be important viral long-distance movement. Analysis of PMTV TGB1 interactions the with host proteins revealed that TGB1 interacts with Nicotiana benthamiana HIPP26 protein, a vascular expressed, metallochaperone that acts as a plasma membrane to nucleus stress signalling relay. PMTV infection upregulated the expression of HIPP26 and altered its subcellular localization from plasmodesmata to the nucleus. Knockdown of NbHIPP26 expression resulted in inhibition of virus long-distance movement, but not the cell-to-cell movement. Together, this data suggests that PMTV hijacks NbHIPP26 to facilitate the long-distance movement of the virus.
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| 7. |
- Kalyandurg, Pruthvi Balachandra, et al.
(författare)
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Spray-Induced Gene Silencing as a Potential Tool to Control Potato Late Blight Disease
- 2021
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Ingår i: Phytopathology. - 0031-949X .- 1943-7684. ; 111, s. 2168-2175
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Tidskriftsartikel (refereegranskat)abstract
- Phytophthora infestans causes late blight disease on potato and tomato and is currently controlled by resistant cultivars or intensive fungicide spraying. Here, we investigated an alternative means for late blight control by spraying potato leaves with double-stranded RNAs (dsRNA) that target the P. infestans genes essential for infection. First, we showed that the sporangia of P. infestans expressing green fluorescent protein (GFP) can take up in vitro synthesized dsRNAs homologous to GFP directly from their surroundings, including leaves, which led to the reduced relative expression of GFP. We further demonstrate the potential of spray-induced gene silencing (SIGS) in controlling potato late blight disease by targeting developmentally important genes in P. infestans such as guanine-nucleotide binding protein beta-subunit (PiGPB1), haustorial membrane protein (PiHmp1), cutinase (PiCut3), and endo-1,3(4)-beta-glucanase (PiEndo3). Our results demonstrate that SIGS can potentially be used to mitigate potato late blight; however, the degree of disease control is dependent on the selection of the target genes.
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| 8. |
- Prado Fortuna Macan, Giovana, et al.
(författare)
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A Detached Leaf Assay for Rapidly Screening Plant Pathogen-Biological Control Agents
- 2022
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Ingår i: Plant Pathology : Method and Protocols. - New York, NY : Springer US. - 9781071625163 ; 2536:2536, s. 449-458
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Bokkapitel (refereegranskat)abstract
- The detached leaf assay (DLA) is a nondestructive method for evaluating interactions between plants and disease-causing agents that allows quick characterization of potential pathogens’ infectivity and plants’ resistance to them. Here we show its utility for also assessing potential biological control agents (BCAs), by demonstrating its applicability for screening potential BCAs for the strawberry (Fragaria × ananassa) pathogen Phytophtora cactorum.
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| 9. |
- Ramesh, Vetukuri, et al.
(författare)
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Effect of RNA silencing suppression activity of chrysanthemum virus B p12 protein on small RNA species
- 2020
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Ingår i: Archives of Virology. - : Springer Science and Business Media LLC. - 0304-8608 .- 1432-8798. ; 165, s. 2953-2959
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Tidskriftsartikel (refereegranskat)abstract
- Chrysanthemum virus B encodes a multifunctional p12 protein that acts as a transcriptional activator in the nucleus and as a suppressor of RNA silencing in the cytoplasm. Here, we investigated the impact of p12 on accumulation of major classes of small RNAs (sRNAs). The results show dramatic changes in the sRNA profiles characterised by an overall reduction in sRNA accumulation, changes in the pattern of size distribution of canonical siRNAs and in the ratio between sense and antisense strands, lower abundance of siRNAs with a U residue at the 5 '-terminus, and changes in the expression of certain miRNAs, most of which were downregulated.
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| 10. |
- Ramesh, Vetukuri, et al.
(författare)
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Spray-induced gene silencing: an innovative strategy for plant trait improvement and disease control
- 2021
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Ingår i: Crop breeding and applied biotechnology. - 1518-7853 .- 1984-7033. ; 21
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Forskningsöversikt (refereegranskat)abstract
- Modern plant breeding is still a time-consuming and costly process, even with the most advanced technologies such as gene editing. Hence, there is an urgent need to develop alternative means for plant trait manipulation and plant protection. RNA interference (RNAi) is a conserved cellular mechanism mediated by naturally occurring double-stranded RNA (dsRNA) and small RNAs (sRNAs) that can target mRNAs for destruction or transcript reduction. Here, we review the potential of technology based on RNAi, called spray-induced gene silencing (SIGS), as an alternative or adjunct to breeding for manipulation of endogenous gene expression in plants or pathogen control. SIGS based on exogenous application of RNA molecules in plants may be especially useful in reducing pest or pathogen impacts, thereby ameliorating biotic stresses and increasing the agronomic performance of crops.
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