scholarly journals Long-term, Sustained Feeding by Asian citrus psyllid Disrupts Salicylic Acid Homeostasis in Sweet Orange

2019 ◽  
Author(s):  
Freddy Ibanez ◽  
Joon Hyuk Suh ◽  
Yu Wang ◽  
Lukasz L. Stelinski
Keyword(s):  
Salicylic Acid ◽  
Methyl Ester ◽  
Molecular Mechanisms ◽  
Sweet Orange ◽  
Plant Immunity ◽  
Diaphorina Citri ◽  
Dihydroxybenzoic Acid ◽  
Candidatus Liberibacter ◽  
Continuous Feeding ◽  
Phloem Feeding

Abstract Abstract Background Phloem-feeding insects are known to modulate the salicylic acid (SA) signaling pathway in various plant-insect interaction models. Diaphorina citri is a phloem feeding vector of the deadly phytopathogens, Candidatus Liberibacter americanus and Candidatus Liberibacter asiaticus, and the interactions of D. citri with its host that may modulate plant defenses are not well understood. The objectives of this study were to investigate the molecular mechanisms involved in transcriptional regulation of SA modification and activation of defense-associated responses in sweet orange (Citrus sinensis) exposed to various durations (7-, 14- and 150- days) of continuous feeding by D. citri. Results We quantified expression of genes involved in SA pathway activation and subsequent modification, as well as, associated SA metabolites (SA methyl ester, 2,3-Dihydroxybenzoic acid and SA 2-O-β-D-glucoside). NPR1 and PR-1 expression was upregulated in plants exposed to continuous feeding by D. citri for 14 days. Expression of BSMT-like, MES1-like and DMR6-like oxygenase, as well as, accumulation of their respective SA metabolites (SA methyl ester, 2,3-Dihydroxybenzoic acid) was significantly higher in plants exposed to continuous feeding by D. citri for 150 days than in those without D. citri infestation. Concomitantly, expression of UGT74F2-like was significantly downregulated and its metabolite, salicylic acid 2-β-D-glucoside, was highly accumulated in trees exposed to 150 d of feeding compared to control trees without D. citri. Conclusions D. citri herbivory differentially regulated transcription and SA-metabolite accumulation in citrus leaves, depending on duration of insect feeding. Our results suggest that prolonged and uninterrupted exposure (150 d) of citrus to D. citri feeding suppressed plant immunity and inhibited growth, which may highlight the importance of vector suppression as part of huanglongbing (HLB) management in citrus. Keywords: salicylic acid, Diaphorina citri, plant defense, metabolomics, gene expression, vector-host interaction, huanglongbing.

scholarly journals Long-term, Sustained Feeding by Asian citrus psyllid Disrupts Salicylic Acid Homeostasis in Sweet Orange

2019 ◽  
Author(s):  
Freddy Ibanez ◽  
Joon Hyuk Suh ◽  
Yu Wang ◽  
Lukasz L. Stelinski
Keyword(s):  
Salicylic Acid ◽  
Methyl Ester ◽  
Molecular Mechanisms ◽  
Sweet Orange ◽  
Plant Immunity ◽  
Diaphorina Citri ◽  
Host Interaction ◽  
Candidatus Liberibacter ◽  
Continuous Feeding ◽  
Phloem Feeding

Abstract Abstract Background Phloem-feeding insects are known to modulate the salicylic acid (SA) signaling pathway in various plant-insect interaction models. Diaphorina citri is a phloem feeding vector of the deadly phytopathogens, Candidatus Liberibacter americanus and Candidatus Liberibacter asiaticus, and the interactions of D. citri with its host that may modulate plant defenses are not well understood. The objectives of this study were to investigate the molecular mechanisms involved in transcriptional regulation of SA modification and activation of defense-associated responses in sweet orange ( Citrus sinensis ) exposed to various durations (7-, 14- and 150- days) of continuous feeding by D. citri . Results We quantified expression of genes involved in SA pathway activation and subsequent modification, as well as, associated SA metabolites (SA methyl ester, 2,3-DHBA, and SA 2-O-β-D-glucoside). NPR1 and PR-1 expression was upregulated in plants exposed to continuous feeding by D. citri for 14 days. Expression of BSMT-like , MES1-like and DMR6-like oxygenase , as well as, accumulation of their respective SA metabolites (SA methyl ester, 2,3-DHBA) was significantly higher in plants exposed to continuous feeding by D. citri for 150 days than in those without D. citri infestation. Concomitantly, expression of UGT74F2-like was significantly downregulated and its metabolite, SA 2-β-D-glucoside, was highly accumulated in trees exposed to 150 d of feeding compared to control trees without D. citri . Conclusions D. citri herbivory differentially regulated transcription and SA-metabolite accumulation in citrus leaves, depending on duration of insect feeding. Our results suggest that prolonged and uninterrupted exposure (150 d) of citrus to D. citri feeding suppressed plant immunity and inhibited growth, which may highlight the importance of vector suppression as part of huanglongbing (HLB) management in citrus. Keywords : salicylic acid, Diaphorina citri , plant defense, metabolomics, gene expression, vector-host interaction, huanglongbing.

scholarly journals Long-term, Sustained Feeding by Asian citrus psyllid Disrupts Salicylic Acid Homeostasis in Sweet Orange

2019 ◽  
Author(s):  
Freddy Ibanez ◽  
Joon Hyuk Suh ◽  
Yu Wang ◽  
Lukasz L. Stelinski
Keyword(s):  
Salicylic Acid ◽  
Methyl Ester ◽  
Molecular Mechanisms ◽  
Sweet Orange ◽  
Plant Immunity ◽  
Dihydroxybenzoic Acid ◽  
Expression Of Genes ◽  
Continuous Feeding ◽  
Citrus Leaves ◽  
Phloem Feeding

Abstract Background Phloem-feeding insects are known to modulate the salicylic acid (SA) signaling pathway in various plant-insect interaction models. Diaphorina citri is a phloem feeding vector of a deadly phytopathogen and interactions with its host that may modulate plant defense are not well understood. The objectives of this study were to investigate the molecular mechanisms involved in transcriptional regulation of SA modification and activation of defense-associated responses in sweet orange ( Citrus sinensis ) exposed to various durations (7-, 14- and 150- days) of continuous feeding by D. citri .. Results We quantified expression of genes involved in SA pathway activation and subsequent modification, as well as, associated SA metabolites (SA methyl ester, 2,3-Dihydroxybenzoic acid and SA 2-O-β-D-glucoside). NPR1 and PR-1 expression was upregulated in plants exposed to continuous feeding by D. citri for 14 days. Expression of BSMT-like , MES1-like and DMR6-like oxygenase , as well as, accumulation of their respective SA metabolites (SA methyl ester, 2,3-Dihydroxybenzoic acid) was significantly higher in plants exposed to continuous feeding by D. citri for 150 days than in those without D. citri infestation. Concomitantly, expression of UGT74F2-like was significantly downregulated and its metabolite, salicylic acid 2-β-D-glucoside, was highly accumulated in trees exposed to 150 d of feeding compared to control trees without D. citri . Conclusions D. citri herbivory differentially regulated transcription and SA-metabolite accumulation in citrus leaves, depending on duration of insect feeding. Our results suggest that prolonged and uninterrupted exposure (150 d) of citrus to D. citri feeding suppressed plant immunity and inhibited growth, which may highlight the importance of vector suppression as part of HLB management in citrus.

scholarly journals Long-term, sustained feeding by Asian citrus psyllid disrupts salicylic acid homeostasis in sweet orange

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Freddy Ibanez ◽  
Joon Hyuk Suh ◽  
Yu Wang ◽  
Lukasz L. Stelinski
Keyword(s):  
Salicylic Acid ◽  
Methyl Ester ◽  
Molecular Mechanisms ◽  
Sweet Orange ◽  
Plant Immunity ◽  
Expression Of Genes ◽  
Pathway Activation ◽  
Continuous Feeding ◽  
Citrus Leaves ◽  
Phloem Feeding

Abstract Background Phloem-feeding insects are known to modulate the salicylic acid (SA) signaling pathway in various plant-insect interaction models. Diaphorina citri is a phloem feeding vector of the deadly phytopathogens, Candidatus Liberibacter americanus and Candidatus Liberibacter asiaticus, and the interactions of D. citri with its host that may modulate plant defenses are not well understood. The objectives of this study were to investigate the molecular mechanisms involved in transcriptional regulation of SA modification and activation of defense-associated responses in sweet orange (Citrus sinensis) exposed to various durations (7-, 14- and 150- days) of continuous feeding by D. citri. Results We quantified expression of genes involved in SA pathway activation and subsequent modification, as well as, associated SA metabolites (SA methyl ester, 2,3-DHBA, and SA 2-O-β-D-glucoside). NPR1 and PR-1 expression was upregulated in plants exposed to continuous feeding by D. citri for 14 days. Expression of BSMT-like, MES1-like and DMR6-like oxygenase, as well as, accumulation of their respective SA metabolites (SA methyl ester, 2,3-DHBA) was significantly higher in plants exposed to continuous feeding by D. citri for 150 days than in those without D. citri infestation. Concomitantly, expression of UGT74F2-like was significantly downregulated and its metabolite, SA 2-β-D-glucoside, was highly accumulated in trees exposed to 150 d of feeding compared to control trees without D. citri. Conclusions D. citri herbivory differentially regulated transcription and SA-metabolite accumulation in citrus leaves, depending on duration of insect feeding. Our results suggest that prolonged and uninterrupted exposure (150 d) of citrus to D. citri feeding suppressed plant immunity and inhibited growth, which may highlight the importance of vector suppression as part of huanglongbing (HLB) management in citrus.

Intracellular life cycle of Candidatus Liberibacter asisticus inside psyllid gut cells

2021 ◽  
Author(s):  
Lin Chun-Yi ◽  
Diann Achor ◽  
Amit Levy
Keyword(s):  
Molecular Mechanisms ◽  
Management Strategies ◽  
Bacterial Invasion ◽  
Diaphorina Citri ◽  
Current Management ◽  
Insect Midgut ◽  
Rapid Spread ◽  
Candidatus Liberibacter ◽  
Infected Insect ◽  
Liberibacter Asiaticus

Candidatus Liberibacter asiaticus (CLas), the devastating pathogen related to Huanglongbing (HLB), is a phloem-limited, fastidious, insect-borne bacterium. Rapid spread of HLB disease relies on CLas propagates efficiently in its vector, the Asian citrus psyllid, Diaphorina citri, in a circulative manner. Understanding the intracellular lifecycle of CLas in psyllid midgut is fundamental to improve current management strategies. Using a microscopic approach within CLas-infected insect midgut, we observed the entry of CLas into gut cells inside vesicles by endocytosis, termed Liberibacter containing vacuoles (LCVs). Endocytosis is followed by the formation of endoplasmic reticulum-related and replication permissive vacuoles (rLCVs). rLCVs then further develop into bigger double membrane autophagosome-like structure, termed autophagy-related vacuole (aLCV). Vesicles, containing CLas egress from aLCV and fuse with the cell membrane. Immunolocalization studies showed that CLas employs endo/exocytosis-like mechanisms that mediates bacterial invasion and egress. Upregulation of autophagy-related genes indicated subversion of host autophagy by CLas in psyllid vector to promote infection. These results indicate that CLas interacts with host cellular machineries to undergo a multistage intracellular cycle through endocytic, secretory, autophagic and exocytic pathways via complex machineries. Potential tactics for HLB controlling can be made depending on further investigations on the knowledge of the molecular mechanisms of CLas intracellular cycle.

A Review of Huanglongbing (Citrus Greening) Management in Citrus Using Nutritional Approaches in China

2011 ◽  
Vol 12 (1) ◽  
pp. 24 ◽  
Author(s):  
Yulu Xia ◽  
Gecheng Ouyang ◽  
Ronald A. Sequeira ◽  
Yu Takeuchi ◽  
Ignacio Baez ◽  
...  
Keyword(s):  
Nutrient Management ◽  
Field Survey ◽  
Cultural Practices ◽  
Sweet Orange ◽  
Asian Citrus Psyllid ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Candidatus Liberibacter ◽  
Citrus Maxima ◽  
Liberibacter Asiaticus

The Asian form of huanglongbing (HLB) is caused by ‘Candidatus Liberibacter asiaticus (Las),’ a phloem-limited bacterium transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama. Nutrient management, together with other cultural practices such as pruning and irrigation, for mitigation of the disease has been practiced in China for many years. Our literature review, field survey, and interviews with Chinese scientists and growers indicate that these cultural practices were generally ineffective for the disease management. However, a nutritional approach in conjunction with other cultural practices such as irrigation can maintain grove productivity for a certain time depending on the type of citrus species/cultivars, the age of the trees, the propagation method of the plants, the Asian citrus psyllid (ACP) (Diaphorina citri Kuwayama) population, and other factors. Symptomatic mature pommelo (Citrus maxima Merr) and sweet orange (C. sinensis L. Osbeck) plants can commonly survive and maintain a certain level of productivity for an additional 4 to 5 years, even longer assuming vigorous ACP control. Accepted for publication 27 June 2011. Published 3 October 2011.

scholarly journals Murraya paniculata and Swinglea glutinosa as Short-Term Transient Hosts of ‘Candidatus Liberibacter asiaticus’ and Implications for the Spread of Huanglongbing

2019 ◽  
Vol 109 (12) ◽  
pp. 2064-2073 ◽  
Author(s):  
Juan Camilo Cifuentes-Arenas ◽  
George Andrew Charles Beattie ◽  
Leandro Peña ◽  
Silvio Aparecido Lopes
Keyword(s):  
Sweet Orange ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Principal Vector ◽  
Dead End ◽  
Valencia Orange ◽  
Murraya Paniculata ◽  
Citrus Rootstock ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus

Murraya paniculata and Swinglea glutinosa are aurantioid hosts of the Asian citrus psyllid (ACP) Diaphorina citri, the principal vector of ‘Candidatus Liberibacter asiaticus’ (Las). Las is the pathogen associated with huanglongbing (HLB), the Asian form of which is the most devastating disease of Citrus species and cultivars (Rutaceae: Aurantioideae). M. paniculata is a common ornamental and S. glutinosa is grown as an ornamental, a citrus rootstock, and a hedgerow fence plant. Because of the uncertain status of these plants as reservoirs of Las, a series of cross-inoculation bioassays were carried out in different environments, using infected Valencia sweet orange (Citrus × aurantium) infected shoot tops as a source of inoculum and D. citri nymphs and adults reared on M. paniculata and S. glutinosa to inoculate pathogen-free Valencia orange plantlets. In contrast to sweet orange, Las was more unevenly distributed and reached much lower titers in M. paniculata and S. glutinosa. Infections in M. paniculata and S. glutinosa were also transient. Very few insects that successfully acquired Las from M. paniculata and S. glutinosa were able to transmit the pathogen to healthy citrus. Transmission rates were low from M. paniculata (1.0%) and S. glutinosa (2.0%) and occurred only in a controlled environment highly favorable to Las and ACP using 10-day-old adults that completed their life cycle on Las-positive plants. Our study showed that in HLB-endemic areas, M. paniculata and S. glutinosa can be deemed as epidemiologically dead-end hosts for Las and are not important alternative hosts of the pathogen for transmission to citrus. However, under a combination of conditions highly favorable to Las infection and transmission and in the absence of effective quarantine procedures, these plants could eventually serve as carriers of Las to regions currently free from HLB.

Salicylic acid signalling: new insights and prospects at a quarter-century milestone

2015 ◽  
Vol 58 ◽  
pp. 101-113 ◽  
Author(s):  
Xiaoyu Liu ◽  
Kristin S. Rockett ◽  
Camilla J. Kørner ◽  
Karolina M. Pajerowska-Mukhtar
Keyword(s):  
Salicylic Acid ◽  
Molecular Mechanisms ◽  
Plant Immunity ◽  
Plant Defence ◽  
Immune Memory ◽  
Quarter Century ◽  
Modern Agriculture ◽  
Signalling Network ◽  
Defence Responses ◽  
Plant Defence Responses

The plant hormone salicylic acid (SA) plays an essential role in the regulation of diverse biological processes throughout the entire lifespan of the plant. Twenty-five years ago, SA first emerged as an endogenous signal capable of inducing plant defence responses both at the site of infection and in the systemic tissue of the plant. Since then, SA-mediated signalling pathways have been extensively characterized and dissected using genetic and biochemical approaches. Current research is largely focused on the identification of novel SA downstream signalling genes, in order to understand their precise contributions to the phytohormonal cross-talk and signalling network. This will subsequently help us to identify novel targets that are important for plant health, and contribute to advances in modern agriculture. In this chapter we highlight recent advances in the field of SA biosynthesis and the discovery of candidates for systemic mobile signals. We also discuss the molecular mechanisms underlying SA perception. In addition, we review the novel SA signalling components that expand the scope of SA functions beyond plant immunity to include plant growth and development, endoplasmic reticulum (ER) stress, DNA repair and homologous recombination. Finally, we shed light on the roles of SA in epigenetically controlled transgenerational immune memory that has long-term benefits for plants.

Prevalent transmission of 'Candidatus Liberibacter asiaticus’ over ‘Ca. Liberibacter americanus’ in a long-term controlled environment

2021 ◽  
Author(s):  
Maria Cândida de Godoy Gasparoto ◽  
Isabela Vescove Primiano ◽  
Renato Bassanezi ◽  
Silvia Afonseca Lourenço ◽  
Luiz Montesino ◽  
...  
Keyword(s):  
Sweet Orange ◽  
Insect Vector ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Citrus Orchards ◽  
Test Plants

In Brazil, citrus huanglongbing (HLB) is associated with ‘Candidatus Liberibacter americanus’ (CLam) and ‘Ca. Liberibacter asiaticus’ (CLas). However, there are few studies about HLB epidemiology when both Liberibacter spp. and its insect vector, the Asian citrus psyllid (ACP, Diaphorina citri), are present. The objective of this work was to compare the transmission of HLB by ACP when both CLam and CLas are present as primary inoculum. Two experiments were performed under screenhouse conditions from April 2008 to January 2012 (experiment 1) and from February 2011 to December 2015 (experiment 2). The experiments were carried out with sweet orange plants infected with CLam or CLas as inoculum source surrounded by sweet orange healthy plants. One hundred Liberibacter-free adult psyllids were monthly confined to the source of inoculum plants for 7 days with subsequent free movement inside the screenhouse. Fortnightly, nymphs and adults of psyllids were monitored. Psyllid and leaf samples were collected periodically for Liberibacter detection by PCR or qPCR. CLas was detected more frequently than CLam in both psyllid and leaf samples. No mixed infections were detected in the psyllids. A clear prevalence of CLas over CLam was observed in both experiments. The final HLB incidences were 16.7 and 14.5% of Liberibacter-positive test plants, and CLas was detected in 92.3 and 93.1% of these infected plants. Mixed infection was observed only in 3.8% of infected test plants in experiment 1. These results endorse the shift in the prevalence of CLam to CLas observed in citrus orchards of São Paulo, Brazil.

scholarly journals Seasonal Variation of ‘Candidatus Liberibacter asiaticus’ Titers in New Shoots of Citrus in Distinct Environments

Plant Disease ◽  
2017 ◽  
Vol 101 (4) ◽  
pp. 583-590 ◽  
Author(s):  
Silvio A. Lopes ◽  
Fernanda Q. B. F. Luiz ◽  
Hermes T. Oliveira ◽  
Juan C. Cifuentes-Arenas ◽  
Laudecir L. Raiol-Junior
Keyword(s):  
Sweet Orange ◽  
Quantitative Polymerase Chain Reaction ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Cumulative Rainfall ◽  
Data Loggers ◽  
Minas Gerais State ◽  
Candidatus Liberibacter ◽  
Liberibacter Asiaticus ◽  
Polymerase Chain

The major citrus area of Brazil occupies near 450,000 ha between the Triângulo Mineiro (TM) region of Minas Gerais State and the south of São Paulo State (SPS). Significant climatic variation occurs between regions which could affect huanglongbing (HLB) progress, which is lower in TM. To investigate this possibility, young sweet orange shoots were sampled periodically over 2 years to determine ‘Candidatus Liberibacter asiaticus’ titers in naturally infected trees in orchards in Analândia, central SPS, and Frutal and Comendador Gomes, within TM. Data-loggers recorded local temperature and relative humidity hourly. In the laboratory, five ‘Ca. L. asiaticus’-free Diaphorina citri adults were placed on each sampled shoot for 48 h to feed and acquire the pathogen. Shoots and insects were individually analyzed by quantitative polymerase chain reaction to determine ‘Ca. L. asiaticus’ titers. The incidence of ‘Ca. L. asiaticus’-positive shoots, ‘Ca. L. asiaticus’ titers, and acquisition rates were lower for shoots from Comendador Gomes than those from Frutal or Analândia. Stronger association was observed between ‘Ca. L. asiaticus’ titers and the number of hours below 15°C (h < 15°C) or above 30°C (h > 30°C), and cumulative rainfall registered during the 15 days prior to sampling of shoots on each occasion. ‘Ca. L. asiaticus’ titers associated positively with h < 15°C and rainfall and negatively with h > 30°C. The slower spread and lower incidence of HLB in TM may be related to lower incidences of ‘Ca. L. asiaticus’-positive young shoots and lower titers of ‘Ca. L. asiaticus’ in the same shoots as a consequence of the warmer and drier conditions.

scholarly journals Salicylic acid mediated immune response of Citrus Sinensis to varying frequencies of herbivory and pathogen inoculation

2020 ◽  
Author(s):  
Freddy Ibanez ◽  
Joon Hyuk Suh ◽  
Yu Wang ◽  
Monique Rivera ◽  
Mamoudou Setamou ◽  
...  
Keyword(s):  
Immune Response ◽  
Salicylic Acid ◽  
Defense Response ◽  
Citrus Sinensis ◽  
Sweet Orange ◽  
Defense Responses ◽  
Insect Vector ◽  
Diaphorina Citri ◽  
Liberibacter Asiaticus

AbstractPlant immunity against pathogens and pests is comprised of complex mechanisms orchestrated by signaling pathways regulated by plant hormones [Salicylic acid (SA) and Jasmonic acid (JA)]. Investigations of plant immune response to phytopathogens and phloem-feeders have revealed that SA plays a critical role in reprogramming of the activity and/or localization of transcriptional regulators via post-translational modifications. We explored the contributing effects of herbivory by a phytopathogen vector [Asian citrus psyllid, Diaphorina citri] and pathogen [Candidatus Liberibacter asiaticus (CLas)] infection on response of sweet orange [Citrus sinensis (L.) Osbeck] using manipulative treatments designed to mimic the types of infestations/infections that citrus growers experience when cultivating citrus in the face of Huanglongbing (HLB) disease. A one-time (7 d) inoculation access period with CLas-infected vectors caused SA-associated upregulation of PR-1, stimulating defense response after a long period of infection without herbivory (270 and 330 days). In contrast, while repeated (monthly) ‘pulses’ of 7 d psyllid feeding injury stimulated immunity in CLas-infected citrus by increasing [SA] in leaves initially (up to 120 d), long-term (270 and 330 days) repeated herbivory caused [SA] to decrease coincident with upregulation of genes associated with SA metabolism (BMST and DMR6). Similarly, transcriptional responses and metabolite (SA and its analytes) accumulation in citrus exposed to a continuously reproducing population of D. citri exhibited a transitory upregulation of genes associated with SA signaling at 120 days and a posterior downregulation after long-term psyllid (adults and nymphs) feeding (270 and 330 days). Herbivory played an important role in regulation of SA accumulation in mature leaves of C. sinensis, whether or not those trees were coincidentally infected with CLas. Our results indicate that prevention of feeding injury inflicted by D. citri from the tritrophic interaction may allow citrus plants to better cope with the consequences of CLas infection, highlighting the importance of vector suppression as a component of managing this cosmopolitan disease.Author SummaryWe explored tritrophic interactions among an insect vector (Diaphorina citri) – phytopathogen (Candidatus Liberibacter asiaticus) – and cultivated fruit crop [sweet orange, Citrus sinensis (L) Osbeck]. Transcriptional and metabolic responses of plants were analyzed over an extended time-course of disease progression after various frequencies of herbivore feeding and durations of pathogen infection using manipulative treatments designed to mimic the types of infestations/infections that citrus growers experience when cultivating citrus in the presence of the devastating citrus disease, huanglongbing. We found that in the absence of coincident psyllid feeding damage, citrus trees could mount a defense response against the pathogen by activating the salicylic acid (SA) pathway. Repeated, monthly ‘pulses’ of herbivory led to pronounced stimulation of SA transcription that was coincident with diminished pathogen titers in plants. Although insect injury initially activated SA-dependent defense responses, continuous and/or long-term (≥ 270 d) herbivory shut down PR-1-dependent defense responses against the pathogen. Our results provide a mechanism explaining how vector suppression contributes to maintaining health of cultivated citrus in areas where huanglongbing is endemic. Our results also point to specific gene targets that may yield novel genotypes expressing tolerance against CLas after appropriate manipulations.

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