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Thakre N, Carver M, Paredes-Montero JR, Mondal M, Hu J, Saberi E, Ponvert N, Qureshi JA, Brown JK. UV-LASER adjuvant-surfactant-facilitated delivery of mobile dsRNA to tomato plant vasculature and evidence of biological activity by gene knockdown in the potato psyllid. PEST MANAGEMENT SCIENCE 2024; 80:2141-2153. [PMID: 38146104 DOI: 10.1002/ps.7952] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 12/13/2023] [Accepted: 12/26/2023] [Indexed: 12/27/2023]
Abstract
BACKGROUND Double-stranded RNA (dsRNA) biopesticides are of interest for the abatement of insect vectors of pathogenic bacteria such as 'Candidatus Liberibacter', which infects both its psyllid and plant hosts. Silencing of genes essential for psyllids, or for Liberibacter, is anticipated to lead to mortality or impeded bacterial multiplication. Foliar delivery is preferred for biopesticide application; however, the cuticle impedes dsRNA penetration into the vasculature. Here, conditions were established for wounding tomato leaves using ultraviolet light amplification by stimulated emissions of radiation (UV-LASER) to promote dsRNA penetration into leaves and vasculature. RESULTS UV-LASER treatment with application of select adjuvants/surfactants resulted in vascular delivery of 100-, 300- and 600-bp dsRNAs that, in general, were correlated with size. The 100-bp dsRNA required no pretreatment, whereas 300- and 600-bp dsRNAs entered the vasculature after UV-LASER treatment only and UV-LASER adjuvant/surfactant treatment, respectively. Of six adjuvant/surfactants evaluated, plant-derived oil combined with an anionic organosilicon compound performed most optimally. Localization of dsRNAs in the tomato vasculature was documented using fluorometry and fluorescence confocal microscopy. The biological activity of in planta-delivered dsRNA (200-250 bp) was determined by feeding third-instar psyllids on tomato leaves post UV-LASER adjuvant/surfactant treatment, with or without psyllid cdc42- and gelsolin dsRNAs. Gene knockdown was quantified by quantitative, real-time polymerase chain reaction with reverse transcription (RT-qPCR) amplification. At 10 days post the ingestion-access period, knockdown of cdc42 and gelsolin expression was 61% and 56%, respectively, indicating that the dsRNAs delivered to the tomato vasculature were mobile and biologically active. CONCLUSION Results indicated that UV-LASER adjuvant/surfactant treatments facilitated the delivery of mobile, biologically active dsRNA molecules to the plant vasculature. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Neha Thakre
- School of Plant Sciences, The University of Arizona, Tucson, AZ, USA
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA
| | - Megan Carver
- School of Plant Sciences, The University of Arizona, Tucson, AZ, USA
| | - Jorge R Paredes-Montero
- Biology Department, Saginaw Valley State University, University Center, USA
- Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral, ESPOL, Campus Gustavo Galindo, Guayaquil, Ecuador
| | - Mosharrof Mondal
- School of Plant Sciences, The University of Arizona, Tucson, AZ, USA
| | - Jiahuai Hu
- School of Plant Sciences, The University of Arizona, Tucson, AZ, USA
| | - Esmaeil Saberi
- Department of Entomology and Nematology, IFAS, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL, USA
| | - Nathaniel Ponvert
- School of Plant Sciences, The University of Arizona, Tucson, AZ, USA
| | - Jawwad A Qureshi
- Department of Entomology and Nematology, IFAS, Southwest Florida Research and Education Center, University of Florida, Immokalee, FL, USA
| | - Judith K Brown
- School of Plant Sciences, The University of Arizona, Tucson, AZ, USA
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Wenninger EJ, Rashed A. Biology, Ecology, and Management of the Potato Psyllid, Bactericera cockerelli (Hemiptera: Triozidae), and Zebra Chip Disease in Potato. ANNUAL REVIEW OF ENTOMOLOGY 2024; 69:139-157. [PMID: 37616600 DOI: 10.1146/annurev-ento-020123-014734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
The potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae), transmits the pathogen "Candidatus liberibacter solanacearum" (Lso), the putative causal agent of zebra chip disease (ZC). ZC is a disease of potato that reduces yield and quality and has disrupted integrated pest management programs in parts of the Americas and New Zealand. Advances in our understanding of the ecological factors that influence ZC epidemiology have been accelerated by the relatively recent identification of Lso and motivated by the steady increase in ZC distribution and the potential for devastating economic losses on a global scale. Management of ZC remains heavily reliant upon insecticides, which is not sustainable from the standpoint of insecticide resistance, nontarget effects on natural enemies, and regulations that may limit such tools. This review synthesizes the literature on potato psyllids and ZC, outlining recent progress, identifying knowledge gaps, and proposing avenues for further research on this important pathosystem of potatoes.
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Affiliation(s)
- Erik J Wenninger
- Department of Entomology, Plant Pathology and Nematology, Kimberly Research & Extension Center, University of Idaho, Kimberly, Idaho, USA;
| | - Arash Rashed
- Department of Entomology, Southern Piedmont Agricultural Research & Extension Center, Virginia Tech, Blackstone, Virginia, USA;
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Fisher TW, Munyaneza JE, Brown JK. Sub-optimal temperatures lead to altered expression of stress-related genes and increased 'C andidatus Liberibacter solanacearum' accumulation in potato psyllid. FRONTIERS IN INSECT SCIENCE 2024; 3:1279365. [PMID: 38469510 PMCID: PMC10926459 DOI: 10.3389/finsc.2023.1279365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 11/23/2023] [Indexed: 03/13/2024]
Abstract
Introduction The potato psyllid Bactericera cockerelli is the insect vector of the fastidious bacterium 'Candidatus Liberibacter solanacearum'. The bacterium infects both B. cockerelli and plant species, causing zebra chip (ZC) disease of potato and vein-greening disease of tomato. Temperatures are known to influence the initiation and progression of disease symptom in the host plant, and seasonal transitions from moderate to high temperatures trigger psyllid dispersal migration to facilitate survival. Methods 'Ca. L. solanacearum' -infected and uninfected psyllids were reared at previously established 'permissible', optimal, and 'non-permissible' and temperatures of 18°C, 24°C, and 30°C, respectively. Gene expression profiles for 'Ca. L. solanacearum'-infected and -uninfected adult psyllids reared at different temperatures were characterized by Illumina RNA-Seq analysis. Bacterial genome copy number was quantified by real-time quantitative-PCR (qPCR) amplification. Results Relative gene expression profiles varied in psyllids reared at the three experimental temperatures. Psyllids reared at 18°C and 30°C exhibited greater fold-change increased expression of stress- and 'Ca. L. solanacearum' invasion-related proteins. Quantification by qPCR of bacterial genome copy number revealed that 'Ca. L. solanacearum' accumulation was significantly lower in psyllids reared at 18°C and 30°C, compared to 24°C. Discussion Temperature is a key factor in the life history of potato psyllid and multiplication/accumulation of 'Ca. L. solanacearum' in both the plant and psyllid host, influences the expression of genes associated with thermal stress tolerance, among others, and may have been instrumental in driving the co-evolution of the pathosystem.
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Affiliation(s)
- Tonja W. Fisher
- School of Plant Sciences, The University of Arizona, Tucson, AZ, United States
| | - Joseph E. Munyaneza
- United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Yakima Agricultural Research Laboratory (YARL), Wapato, WA, United States
| | - Judith K. Brown
- School of Plant Sciences University of Arizona, Tucson, AZ, United States
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Saberi E, Mondal M, Paredes-Montero JR, Nawaz K, Brown JK, Qureshi JA. Optimal dsRNA Concentration for RNA Interference in Asian Citrus Psyllid. INSECTS 2024; 15:58. [PMID: 38249064 PMCID: PMC10816725 DOI: 10.3390/insects15010058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/07/2024] [Accepted: 01/10/2024] [Indexed: 01/23/2024]
Abstract
The Asian citrus psyllid (ACP) is a citrus pest and insect vector of "Candidatus Liberibacter asiaticus", the causal agent of citrus greening disease. Double-stranded RNA (dsRNA) biopesticides that trigger RNA interference (RNAi) offer an alternative to traditional insecticides. Standardized laboratory screening of dsRNA requires establishing the minimal effective concentration(s) that result in effective RNAi "penetrance" and trigger RNAi, resulting in one or more measurable phenotypes, herein, significant gene knockdown and the potential for mortality. In this study, knockdown was evaluated for a range of dsRNA concentrations of three ACP candidate genes, clathrin heavy chain (CHC), vacuolar ATPase subunit A (vATPase-A), and sucrose non-fermenting protein 7 (Snf7). Gene knockdown was quantified for ACP teneral adults and 3rd instar nymphs allowed a 48 h ingestion-access period (IAP) on 10, 50,100, 200, and 500 ng/µL dsRNA dissolved in 20% sucrose followed by a 5-day post-IAP on orange jasmine shoots. Significant gene knockdown (p < 0.05) in ACP third instar nymphs and adults ranged from 12-34% and 18-39%, 5 days post-IAP on dsRNA at 10-500 and 100-500 ng/µL, respectively. The threshold concentration beyond which no significant gene knockdown and adult mortality was observed post-48 h IAP and 10-day IAP, respectively, was determined as 200 ng/µL, a concentration indicative of optimal RNAi penetrance.
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Affiliation(s)
- Esmaeil Saberi
- Southwest Florida Research and Education Center, Department of Entomology and Nematology, IFAS, University of Florida, Immokalee, FL 34142, USA;
| | - Mosharrof Mondal
- School of Plant Sciences, The University of Arizona, Tucson, AZ 85721, USA; (M.M.); (K.N.)
- RNAissance Ag, LLC, Saint Louis, MO 63132, USA
| | - Jorge R. Paredes-Montero
- Biology Department, Saginaw Valley State University, University Center, MI 48710, USA;
- Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral, ESPOL, Campus Gustavo Galindo, Km 30.5 Vía Perimetral, Guayaquil EC090112, Ecuador
| | - Kiran Nawaz
- School of Plant Sciences, The University of Arizona, Tucson, AZ 85721, USA; (M.M.); (K.N.)
- RNAissance Ag, LLC, Saint Louis, MO 63132, USA
| | - Judith K. Brown
- School of Plant Sciences, The University of Arizona, Tucson, AZ 85721, USA; (M.M.); (K.N.)
| | - Jawwad A. Qureshi
- Southwest Florida Research and Education Center, Department of Entomology and Nematology, IFAS, University of Florida, Immokalee, FL 34142, USA;
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Arad N, Paredes-Montero JR, Mondal MH, Ponvert N, Brown JK. RNA interference-mediated knockdown of genes involved in sugar transport and metabolism disrupts psyllid Bactericera cockerelli (Order: Hemiptera) gut physiology and results in high mortality. FRONTIERS IN INSECT SCIENCE 2023; 3:1283334. [PMID: 38469486 PMCID: PMC10926392 DOI: 10.3389/finsc.2023.1283334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 10/02/2023] [Indexed: 03/13/2024]
Abstract
Introduction The causal agent of zebra chip of potato and vein-greening diseases of tomato is "Candidatus Liberibacter solanacearum" (CLso), a fastidious bacterium transmitted by the potato psyllid. In the absence of disease-resistant cultivars, disease management has relied on minimizing vector population size to reduce CLso transmission, which requires frequent insecticide applications. There is growing interest in the use of RNA interference (RNAi) technology to supplant traditional insecticides with biopesticides. This requires knowledge of genes essential for insect livelihood whose knockdown leads to significant mortality or other phenotypes. Such candidate genes can be evaluated by reverse genetics approaches to further corroborate predicted gene function. Methods Here, five potato psyllid genes involved in sugar homeostasis in the potato psyllid gut, α-glucosidase1 (AGLU1), aquaporin2 (AQP2), facilitated trehalose transporter1 (TRET1), Trehalase1 (TRE1), and Trehalase2 (TRE2), were investigated as candidates for effective gene silencing. Potato psyllid dsRNAs were designed to optimize knockdown of gene targets. Third instar PoP nymphs were given a 48-hr ingestion-access period (IAP) on individual or groups of dsRNA in 20% sucrose. Mortality was recorded 0, 3, 5, 7, and 9 days post-IAP. Gene knockdown was analyzed 9 days post-IAP by quantitative real-time reverse-transcriptase polymerase chain reaction amplification. Results The individual or stacked dsRNA combinations resulted in 20-60% and 20-40% knockdown, respectively, while subsequent psyllid mortality ranged from 20-40% to >60% for single and stacked dsRNA combinations, respectively. Reverse genetics analysis showed that simultaneous knockdown of the five selected candidate genes with predicted functions in pathways involved in sugar-homeostasis, metabolism, and -transport yielded the highest mortality, when compared with single or combinations of targets. Discussion Results confirmed the functions afforded by psyllid gut genes responsible for osmotic homeostasis and sugar metabolism/transport are essential for livelihood, identifying them as potentially lucrative RNAi biopesticide targets and highlighted the translational relevance of targeting multiple nodes in a physiological pathway simultaneously.
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Affiliation(s)
- Neda Arad
- School of Plant Sciences, The University of Arizona, Tucson, AZ, United States
| | - Jorge R. Paredes-Montero
- School of Plant Sciences, The University of Arizona, Tucson, AZ, United States
- Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral, ESPOL, Guayaquil, Guayas, Ecuador
| | | | - Nathaniel Ponvert
- School of Plant Sciences, The University of Arizona, Tucson, AZ, United States
| | - Judith K. Brown
- School of Plant Sciences, The University of Arizona, Tucson, AZ, United States
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He R, Fisher TW, Saha S, Peiz-Stelinski K, Willis MA, Gang DR, Brown JK. Differential gene expression of Asian citrus psyllids infected with ' Ca. Liberibacter asiaticus' reveals hyper-susceptibility to invasion by instar fourth-fifth and teneral adult stages. FRONTIERS IN PLANT SCIENCE 2023; 14:1229620. [PMID: 37662178 PMCID: PMC10470031 DOI: 10.3389/fpls.2023.1229620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 07/10/2023] [Indexed: 09/05/2023]
Abstract
The bacterial pathogen Candidatus Liberibacter asiaticus (CLas) is the causal agent of citrus greening disease. This unusual plant pathogenic bacterium also infects its psyllid host, the Asian citrus psyllid (ACP). To investigate gene expression profiles with a focus on genes involved in infection and circulation within the psyllid host of CLas, RNA-seq libraries were constructed from CLas-infected and CLas-free ACP representing the five different developmental stages, namely, nymphal instars 1-2, 3, and 4-5, and teneral and mature adults. The Gbp paired-end reads (296) representing the transcriptional landscape of ACP across all life stages and the official gene set (OGSv3) were annotated based on the chromosomal-length v3 reference genome and used for de novo transcript discovery resulting in 25,410 genes with 124,177 isoforms. Differential expression analysis across all ACP developmental stages revealed instar-specific responses to CLas infection, with greater overall responses by nymphal instars, compared to mature adults. More genes were over-or under-expressed in the 4-5th nymphal instars and young (teneral) adults than in instars 1-3, or mature adults, indicating that late immature instars and young maturing adults were highly responsive to CLas infection. Genes identified with potential for direct or indirect involvement in the ACP-CLas circulative, propagative transmission pathway were predominantly responsive during early invasion and infection processes and included canonical cytoskeletal remodeling and endo-exocytosis pathway genes. Genes with predicted functions in defense, development, and immunity exhibited the greatest responsiveness to CLas infection. These results shed new light on ACP-CLas interactions essential for pathogenesis of the psyllid host, some that share striking similarities with effector protein-animal host mechanisms reported for other culturable and/or fastidious bacterial- or viral- host pathosystems.
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Affiliation(s)
- Ruifeng He
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
- Soybean Genomics and Improvement Laboratory, US Department of Agriculture (USDA)-Agricultural Research Service (ARS), Beltsville, MD, United States
| | - Tonja W. Fisher
- School of Plant Sciences, University of Arizona, Tucson, AZ, United States
| | - Surya Saha
- Sol Genomics Network, Boyce Thompson Institute, Ithaca, NY, United States
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, United States
| | - Kirsten Peiz-Stelinski
- Citrus Research and Education Center, Department of Entomology and Nematology, University of Florida, Lake Alfred, FL, United States
| | - Mark A. Willis
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - David R. Gang
- Institute of Biological Chemistry, Washington State University, Pullman, WA, United States
| | - Judith K. Brown
- School of Plant Sciences, University of Arizona, Tucson, AZ, United States
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Mondal M, Carver M, Brown JK. Characteristics of environmental RNAi in potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Psylloidea: Triozidae). Front Physiol 2022; 13:931951. [PMID: 36330211 PMCID: PMC9623324 DOI: 10.3389/fphys.2022.931951] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 09/20/2022] [Indexed: 11/23/2022] Open
Abstract
RNA interference (RNAi) has potential to become a major tool for integrated management of insect pests of agricultural crops based on sequence-specificity and low doses of rapidly biodegradable dsRNA. Deploying ‘environmental RNAi’ for control of insect vectors of plant pathogens is of increasing interest for combatting emerging plant diseases. Hemipteran insect vectors, including psyllids, are vascular feeders, making their development difficult to control specifically by targeting with pesticidal chemistries. Psyllids transmit “Candidatus Liberibacter solanacearum” the causal organism of potato zebra chip and tomato vein greening diseases, transmitted, respectively, by the potato or tomato psyllid (PoP). Until now, the optimal effective concentration(s) of double-stranded RNA (dsRNA) required for significant gene knockdown and RNAi persistence in PoP have not been determined. The objective of this study was to optimize RNAi in young PoP adults and 3rd instars for screening by oral delivery of dsRNAs. The minimal effective dsRNA concentrations required for robust knockdown and persistence were evaluated by delivering seven concentrations spanning 0.1 ng/μL to 500 ng/μL over post ingestion-access periods (IAP) ranging from 48 h to 12 days. The PoP gene candidates evaluated as targets were vacuolar ATPase subunit A, clathrin heavy chain, and non-fermenting protein 7, which were evaluated for knockdown by qPCR amplification. The minimum and/or the second most effective dsRNA concentration resulting in effective levels of gene knockdown was 100 ng/μL for all three targets. Higher concentrations did not yield further knockdown, indicating potential RISC saturation at the higher doses. Gene silencing post-IAP of 100 ng/μL dsRNA persisted for 3–5 days in adults and nymphs, with the PoP 3rd instar, followed by teneral and mature adults, respectively, exhibiting the most robust RNAi-response.
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Affiliation(s)
- Mosharrof Mondal
- School of Plant Sciences, The University of Arizona, Tucson, AZ, United States
- RNAissance Ag LLC, St. Louis, MO, United States
| | - Megan Carver
- School of Plant Sciences, The University of Arizona, Tucson, AZ, United States
| | - Judith K. Brown
- School of Plant Sciences, The University of Arizona, Tucson, AZ, United States
- *Correspondence: Judith K. Brown,
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