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Sample records for adult diaphorina citri

  1. Relationships between adult abdominal color and reproductive potential in Diaphorina citri (Hemiptera: Psyllidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diaphorina citri Kuwayama (Hemiptera: Psyllidae), a vector of huanglongbing (citrus greening disease), exhibits three more or less distinct abdominal colors in the adult stage: gray/brown, blue/green, and orange/yellow. A previous report showed that—relative to blue/green individuals—gray/brown indi...

  2. Observations on the entomopathogenic fungus Hirsutella citriformis attacking adult Diaphorina citri (Hemiptera: Psyllid) in a managed citrus grove

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two-year field study was conducted in an orange grove (0.7 ha) in Florida to characterize the phenology of the entomopathogen Hirsutella citriformis Speare infecting adults of the Asian citrus psyllid, Diaphorina citri Kuwayama. On the average over the two-year study, 23 percent of adults observed...

  3. Effects of freezes on survival of Diaphorina citri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus in Florida is occasionally subjected to freezing temperatures. No information was available on the effect of freezing temperatures on mortality of Asian citrus psyllid (Diaphorina citri) in Florida. Studies were therefore initiated to assess mortality rates of D. citri eggs, nymphs and adults...

  4. Within-orchard edge effects of the azimuth of the sun on Diaphorina citri adults in mature orchards

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB) has been considered the most devastating disease of citrus. The bacterium and vector associated with HLB in Florida are ‘Candidatus Liberibacter asiaticus’ and Diaphorina citri (Asian citrus psyllid), respectively. D. citri is positively phototropic, and higher populations have b...

  5. Disrupting mating behavior of Diaphorina citri (Liviidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Severe economic damage from citrus greening disease, caused by ‘Candidatus Liberibacter asiaticus’ bacteria, has stimulated development of methods to reduce mating and reproduction in populations of its insect vector, Diaphorina citri (Hemiptera: Liviidae). Male D. citri find mating partners by walk...

  6. Behavioral plasticity in Diaphorina citri feeding on different citrus tissues

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian Citrus Psyllid (Diaphorina citri) is a vector of Candidatus Liberibacter asiaticus (CLas), a phloem-limited bacterial pathogen of citrus. While psyllid nymphs are obligate feeders on young flush leaves, adults can be found on leaves of any age. To understand risk of transmission of CLas, i...

  7. Asian citrus psyllid genome (Diaphorina citri, Hemiptera)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Psyllid genome is a scientific breakthrough in that it opens the psyllid genetic blueprint to investigations of all questions ranging from taxonomic origins to the understanding of developmental biology, to the acquisition and transmission of pathogens. The Asian citrus psyllid, Diaphorina citri...

  8. Oral delivery of double-stranded RNAs induces mortality in nymphs and adults of the Asian citrus psyllid, Diaphorina citri

    PubMed Central

    Galdeano, Diogo Manzano; Breton, Michèle Claire; Lopes, João Roberto Spotti; Falk, Bryce W.

    2017-01-01

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most important citrus pests. ACP is the vector of the phloem-limited bacteria Candidatus Liberibacter americanus and Candidatus Liberibacter asiaticus, the causal agents of the devastating citrus disease huanglongbing (HLB). The management of HLB is based on the use of healthy young plants, eradication of infected plants and chemical control of the vector. RNA interference (RNAi) has proven to be a promising tool to control pests and explore gene functions. Recently, studies have reported that target mRNA knockdown in many insects can be induced through feeding with double-stranded RNA (dsRNA). In the current study, we targeted the cathepsin D, chitin synthase and inhibitor of apoptosis genes of adult and nymph ACP by feeding artificial diets mixed with dsRNAs and Murraya paniculata leaves placed in dsRNAs solutions, respectively. Adult ACP mortality was positively correlated with the amount of dsRNA used. Both nymphs and adult ACP fed dsRNAs exhibited significantly increased mortality over time compared with that of the controls. Moreover, qRT-PCR analysis confirmed the dsRNA-mediated RNAi effects on target mRNAs. These results showed that RNAi can be a powerful tool for gene function studies in ACP and perhaps for HLB control. PMID:28282380

  9. Oral delivery of double-stranded RNAs induces mortality in nymphs and adults of the Asian citrus psyllid, Diaphorina citri.

    PubMed

    Galdeano, Diogo Manzano; Breton, Michèle Claire; Lopes, João Roberto Spotti; Falk, Bryce W; Machado, Marcos Antonio

    2017-01-01

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most important citrus pests. ACP is the vector of the phloem-limited bacteria Candidatus Liberibacter americanus and Candidatus Liberibacter asiaticus, the causal agents of the devastating citrus disease huanglongbing (HLB). The management of HLB is based on the use of healthy young plants, eradication of infected plants and chemical control of the vector. RNA interference (RNAi) has proven to be a promising tool to control pests and explore gene functions. Recently, studies have reported that target mRNA knockdown in many insects can be induced through feeding with double-stranded RNA (dsRNA). In the current study, we targeted the cathepsin D, chitin synthase and inhibitor of apoptosis genes of adult and nymph ACP by feeding artificial diets mixed with dsRNAs and Murraya paniculata leaves placed in dsRNAs solutions, respectively. Adult ACP mortality was positively correlated with the amount of dsRNA used. Both nymphs and adult ACP fed dsRNAs exhibited significantly increased mortality over time compared with that of the controls. Moreover, qRT-PCR analysis confirmed the dsRNA-mediated RNAi effects on target mRNAs. These results showed that RNAi can be a powerful tool for gene function studies in ACP and perhaps for HLB control.

  10. Postharvest quarantine treatments for Diaphorina citri on infested curry leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies were conducted to evaluate treatments that reduce survival and attachment of Diaphorina citri nymphs on infested curry leaves (Bergera koenigii). Decontamination of curry leaves infested with D. citri in relation to disinfectant (none or Pro-San), temperature (0, 40, and 50°C), and treatment...

  11. Temporal response and attraction of Diaphorina citri to visual stimuli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As the vector of the global disease of citrus greening or huanglongbing, Asian citrus pysllids, Diaphorina citri Kuwayama (Hemiptera; Liviidae) are the greatest threat to the worldwide citrus industry. Critical to management of D. citri and huanglongbing, is optimization of surveillance methodologie...

  12. The complete mitochondrial genome sequence of Diaphorina citri (Hemiptera: Psyllidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The first complete mitochondrial genome (mitogenome) sequence of Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae), from Guangzhou, China is presented. The circular mitogenome is 14,996 bp in length with an A+T content of 74.5%, and contains 13 protein-coding genes (PCGs), 22 tRNA genes ...

  13. Vibrational communication between the sexes in Diaphorina citri (Hemiptera: Psyllidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We examined the substrate-borne vibrational signals used in communication between the sexes in Diaphorina citri Kuwayama (Hemiptera: Psyllidae), a vector of huanglongbing (an economically devastating disease of citrus), in an anechoic chamber and an olfactometer. Males and females both primarily pro...

  14. Spectral sensitivity of the Asian citrus psyllid, Diaphorina citri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian Citrus psyllid, Diaphorina citri, as a vector of the bacteria causing citrus greening, is considered one of the most important citrus pests globally. Movement of infected psyllids onto uninfected young citrus remains a key concern for the maintenance of citrus production. Attraction of d...

  15. Asian citrus psyllid genome (Diaphorina citri, Hemiptera)-Update 2013

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The psyllid genome is a scientific breakthrough that opens the psyllid genetic blueprint to investigations of all questions ranging from taxonomic origins to the understanding of developmental biology, to the acquisition and transmission of pathogens. The Asian citrus psyllid, Diaphorina citri (Hemi...

  16. Complete Genome Sequence of the Largest Known Flavi-Like Virus, Diaphorina citri flavi-like virus, a Novel Virus of the Asian Citrus Psyllid, Diaphorina citri

    PubMed Central

    Matsumura, Emilyn E.; Nerva, Luca; Nigg, Jared C.; Falk, Bryce W.

    2016-01-01

    A novel flavi-like virus tentatively named Diaphorina citri flavi-like virus (DcFLV) was identified in field populations of Diaphorina citri through small RNA and transcriptome sequencing followed by reverse transcription (RT)-PCR. We report here the complete nucleotide sequence and genome organization of DcFLV, the largest flavi-like virus identified to date. PMID:27609921

  17. First record of Diaphorina citri (Hemiptera: Psyllidae) in Ecuador infesting urban citrus and orange jasmine trees.

    PubMed

    Cornejo, J F; Chica, E J

    2014-01-01

    Adults and nymphs of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), were collected in the Guayaquil, Samborondón, and Durán cantons in coastal Ecuador. Psyllids were found in high numbers in citrus (Citrus spp., Sapindales: Rutaceae) and orange jasmine (Murraya exotica [L.] Jack, Sapindales: Rutaceae) trees within the Guayaquil-Samborondon-Duran conurbation; however, none was found during scoutings in the main citrus producing areas in coastal Ecuador. To the best of our knowledge, this is the first report of D. citri in Ecuador and the Pacific coastal plain of South America.

  18. Behavioral, Ultrastructural and Chemical Studies on the Honeydew and Waxy Secretions by Nymphs and Adults of the Asian Citrus Psyllid Diaphorina citri (Hemiptera: Psyllidae)

    PubMed Central

    Ammar, El-Desouky; Alessandro, Rocco; Shatters Jr, Robert G.; Hall, David G.

    2013-01-01

    The Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Psyllidae) is the primary vector of the bacterium causing citrus huanglongbing (citrus greening), the most serious disease of citrus worldwide. Psyllids and other hemipterans produce large amounts of honeydew, which has been used previously as an indicator of phloem sap composition and insect feeding or metabolism. Behavioral, ultrastructural and chemical studies on ACP, its honeydew and waxy secretions showed important differences between nymphs, males and females, and suggested some mechanisms by which the psyllids, especially nymphs and adult females, can minimize their contamination with honeydew excretions. The anal opening in ACP, near the posterior end of the abdomen, is on the ventral side in nymphs and on the dorsal side in adult males and females. Video recordings showed that adult males produce clear sticky droplets of honeydew gently deposited behind their body on the leaf surface, whereas adult females produce whitish honeydew pellets powerfully propelled away from the female body, probably to get their excretions away from eggs and newly hatched nymphs. ACP nymphs produce long ribbons or tubes of honeydew that frequently stay attached to the exuviae after molting, or drop when feeding on the lower side of citrus leaves. Furthermore, honeydew excretions of both nymphs and adult females are covered with a thin layer of whitish waxy material ultrastructurally composed of a convoluted network of long fine filaments or ribbons. This material is extruded from intricate arrays of wax pores in the circumanal ring (around the anus) that is found in nymphs and females but not in males of ACP or other psyllid species. Infrared microscopy and mass spectroscopy revealed that, in addition to various sugars, honeydew excretions of ACP nymphs and females are covered with a thin layer of wax similar in profile to ester waxes. PMID:23762268

  19. Diaphorina citri (Hemiptera:Liviidae) abundance in Puerto Rico declines with elevation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diaphorina citri is the primary vector of Hunglongbing disease, the most devastating disease of citrus. Diaphorina citri populations in Puerto Rico were monitored with yellow sticky traps on citrus trees at different elevations, ranging from 10 to 880 m above sea level. Trapping was conducted in Mar...

  20. Biology of Diaphorina citri (Homoptera: Psyllidae) on four host plants.

    PubMed

    Tsai, J H; Liu, Y H

    2000-12-01

    The biology of the citrus psyllid Diaphorina citri Kuwayama was studied at 25 degrees C on four commonly grown citrus and related plants [rough lemon, Citrus jambhiri Lush; sour orange, C aurantium L.; grapefruit, C. paradisi Macfadyen; and orange jessamine, Murraya paniculata (L.) Jack] in the laboratory. The biological characteristics of each life stage are described. The average egg incubation periods on orange jessamine, grapefruit, rough lemon, and sour orange varied very little (4.1-4.2 d). The average nymphal developmental periods on these four host plants were essentially the same except the fifth stadium. Survival of immatures on orange jessamine, grapefruit, rough lemon, and sour orange was 75.4, 84.6, 78.3, and 68.6%, respectively. Female adults lived an average of 39.7, 39.7, 47.6, and 43.7 d on these respective host plants. The average number of eggs laid per female on grapefruit (858 eggs) was significantly more than those on other hosts (P < 0.05). The intrinsic rate of natural increase (r(m)) for D. citri on grapefruit was highest. Jackknife estimates of r(m) varied from 0.188 on grapefruit to 0.162 on orange jessamine and rough lemon. The mean population generation time on these hosts ranged from 31.6 to 34.1 d. The continuous flushes produced by orange jessamine could play an important role in maintaining high populations of this vector when the new flushes are not available in the commercial citrus groves.

  1. Host plant affects morphometric variation of Diaphorina citri (Hemiptera: Liviidae)

    PubMed Central

    Paris, Thomson M.; Hall, David G.; Hentz, Matthew G.; Hetesy, Gabriella; Stansly, Philip A.

    2016-01-01

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most serious citrus pests worldwide due to its role as vector of huanglongbing or citrus greening disease. While some optimal plant species for ACP oviposition and development have been identified, little is known of the influence of host plants on ACP size and shape. Our goal was to determine how size and shape of ACP wing and body size varies when development occurs on different host plants in a controlled rearing environment. ACP were reared on six different rutaceous species; Bergera koenigii, Citrus aurantifolia, Citrus macrophylla, Citrus maxima, Citrus taiwanica and Murraya paniculata. Adults were examined for morphometric variation using traditional and geometric analysis based on 12 traits or landmarks. ACP reared on C. taiwanica were consistently smaller than those reared on the other plant species. Wing aspect ratio also differed between C. maxima and C. taiwanica. Significant differences in shape were detected with those reared on M. paniculata having narrower wings than those reared on C. macrophylla. This study provides evidence of wing size and shape differences of ACP based on host plant species which potentially may impact dispersal. Further study is needed to determine if behavioral and physiological differences are associated with the observed phenotypic differences. PMID:27833820

  2. Host plant affects morphometric variation of Diaphorina citri (Hemiptera: Liviidae).

    PubMed

    Paris, Thomson M; Allan, Sandra A; Hall, David G; Hentz, Matthew G; Hetesy, Gabriella; Stansly, Philip A

    2016-01-01

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most serious citrus pests worldwide due to its role as vector of huanglongbing or citrus greening disease. While some optimal plant species for ACP oviposition and development have been identified, little is known of the influence of host plants on ACP size and shape. Our goal was to determine how size and shape of ACP wing and body size varies when development occurs on different host plants in a controlled rearing environment. ACP were reared on six different rutaceous species; Bergera koenigii, Citrus aurantifolia, Citrus macrophylla, Citrus maxima, Citrus taiwanica and Murraya paniculata. Adults were examined for morphometric variation using traditional and geometric analysis based on 12 traits or landmarks. ACP reared on C. taiwanica were consistently smaller than those reared on the other plant species. Wing aspect ratio also differed between C. maxima and C. taiwanica. Significant differences in shape were detected with those reared on M. paniculata having narrower wings than those reared on C. macrophylla. This study provides evidence of wing size and shape differences of ACP based on host plant species which potentially may impact dispersal. Further study is needed to determine if behavioral and physiological differences are associated with the observed phenotypic differences.

  3. Temperature Studies with the Asian Citrus Psyllid, Diaphorina citri: Cold Hardiness and Temperature Thresholds for Oviposition

    PubMed Central

    Hall, David G.; Wenninger, Erik J.; Hentz, Matthew G.

    2011-01-01

    This study was conducted to obtain information on the cold hardiness of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), in Florida and to assess upper and lower temperature thresholds for oviposition. The psyllid is an important pest in citrus because it transmits the bacterial pathogens responsible for citrus greening disease, Huanglongbing, considered the most serious citrus disease worldwide. D. citri was first found in Florida during 1998, and the disease was discovered during 2005. Little was known regarding cold hardiness of D. citri, but Florida citrus is occasionally subjected to notable freeze events. Temperature and duration were each significant sources of variation in percent mortality of D. citri subjected to freeze events. Relatively large percentages of adults and nymphs survived after being exposed for several hours to temperatures as low as -5 to -6° C. Relatively large percentages of eggs hatched after being exposed for several hours to temperatures as low as -8° C. Research results indicated that adult D. citri become cold acclimated during the winter through exposure to cooler winter temperatures. There was no evidence that eggs became cold acclimated during winter. Cold acclimation in nymphs was not investigated. Research with adult D. citri from laboratory and greenhouse colonies revealed that mild to moderate freeze events were usually nonlethal to the D. citri irrespective of whether they were cold acclimated or not. Upper and lower temperature thresholds for oviposition were investigated because such information may be valuable in explaining the geographic distribution and potential spread of the pest from Florida as well as how cooler winter temperatures might limit population growth. The estimated lower and upper thresholds for oviposition were 16.0 and 41.6° C, respectively; the estimated temperature of peak oviposition over a 48 h period was 29.6° C. PMID:21870969

  4. Survey of endosymbionts in the Diaphorina citri metegenome and assembly of a Wolbachia wDi draft genome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diaphorina citri, the Asian citrus psyllid,(Hemiptera) is the insect vector of Candidatus Liberibacter asiaticus, the presumed cause of citrus greening disease, known as huanglongbing. Sequencing of the Diaphorina citri metagenome has been initiated to gain better understanding of the biology of D. ...

  5. The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri

    PubMed Central

    Stockton, Dara G.; Martini, Xavier; Patt, Joseph M.; Stelinski, Lukasz L.

    2016-01-01

    Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a) whether development on specific host plant species influenced host plant preference in mature D. citri; and b) the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24–48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate Rutaceae in the area

  6. Cloning and expressing a highly functional and substrate specific farnesoic acid o-methyltransferase from the Asian citrus psyllid (Diaphorina citri Kuwayama)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri, transmits a phloem-limited bacterium, Candidatus Liberibacter asiaticus that causes citrus greening disease. Because juvenile hormone (JH) plays an important role in adult and nymphal development, we studied the final steps in juvenile hormone biosynthesis...

  7. Responses of Diaphorina citri (Hemiptera: Psyllidae) to conspecific vibrational signals and synthetic mimics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mate-seeking in Diaphorina citri Kuwayama, a vector of the economically damaging huanglongbing citrus disease, typically includes male-female duetting behaviors. First, the male calls by beating its wings at ca. 170-250 Hz, producing vibrations that are transmitted along the host tree branches to th...

  8. Entomopathogenic fungi infecting the Asian citrus psyllid, Diaphorina citri (Homoptera: Psyllidae), in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri is an invasive pest that vectors citrus greening disease. In 2005-2006 mycosed psyllids displaying two phenotypes were collected in central Florida. The major pathogen, identified by morphological and genetic analyses, was a novel isolate related to Hirsute...

  9. Correlation of an electrical penetration graph waveform with walking by Asian citrus psyllid, Diaphorina citri Kuwayama

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electrical penetration graph (EPG) monitoring is being used to study how feeding behavior of the Asian citrus psyllid (ACP) (Diaphorina citri Kuwayama) changes in response to insecticides, in an effort to improve the efficacy of widespread insecticide treatments against the insect in Florida citrus....

  10. Gender differences and effect of photophase on Asian citrus psyllid (Diaphorina citri Kuwayama) feeding behavior

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), thought to be primarily a phloem-feeding insect, transmits the presumptive pathogen for Huanglongbing, ‘Candidatus Liberibacter asiaticus’. Because this bacterium is restricted to the phloem and bacterial transmission is the res...

  11. Repellency of Selected Psidium guajava cultivars to the Asian citrus psyllid, Diaphorina citri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Asiatic huanglongbing (HLB)(also known as citrus greening disease) is the most devastating disease of citrus worldwide. It is caused by a bacterium ‘Candidatus Liberibacter asiaticus’ and transmitted by the Asian citrus psyllid (ACP), Diaphorina citri. Considerable research has been conducted toward...

  12. Draft genome sequence of “Candidatus Liberibacter asiaticus” from Diaphorina citri in Guangdong, China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The draft genome sequence of “Candidatus Liberibacter asiaticus” strain YCPsy from an Asian citrus psyllid (Diaphorina citri) in Guangdong of China is reported. The YCPsy strain has a genome size of 1,233,647 bp, 36.5% G+C content, 1,171 open reading frames (ORFs), and 53 RNAs....

  13. Larval development of Diaphorencyrtus aligarhensis (Hymenoptera: Encyrtidae) an endoparasitoid of Diaphorina citri (Homoptera: Psyllidae).

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The encyrtid koinobiont endoparasitoid Diaphorencyrtus aligarhensis (Shafee, Alam and Agarwal) is an imported biological control agent being released in Florida against the Asian citrus psyllid, Diaphorina citri Kuwayama. The eggs and early larvae were found free-floating within the hemocoel. Larvae...

  14. Chemical and behavioral analysis of the cuticular hydrocarbons from Asian citrus psyllid, Diaphorina citri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB) is the most destructive disease of citrus worldwide. Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the vector of the phloem-inhabiting bacterium, Candidatus Liberibacter asiaticus, which is presumed to cause HLB. Laboratory and field studies were cond...

  15. Effects of temperature, photoperiod, and rainfall on morphometric variation of Diaphorina citri (Hemiptera: Liviidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phenotypic plasticity provides a mechanism by which an organism can adapt to new or changing environments. Earlier studies have demonstrated the variability of Diaphorina citri Kuwayama (Asian citrus psyllid) population dynamics, but no analysis of morphological changes induced by seasonal or artifi...

  16. Low incidence of Candidatus Liberibacter asiaticus in Diaphorina citri and its host plant Murraya paniculata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide. Candidatus Liberibacter asiaticus is the prevalent species of three HLB-associated Liberibacter species, which is vectored by the psyllid Diaphorina citri. The vector and the bacteria have host plants outside Citrus, ...

  17. Internal extracellular bacteria of Diaphorina citri Kuwayama (Hemiptera: Psyllidae), the Asian citus psyllid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Internal bacteria were isolated and cultured from the Asian Citrus Psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), the insect which transmits the plant-infecting bacteria, Candidatus Liberibacter, known to infect and kill citrus trees, known as citrus greening disease. The bacteria from Di...

  18. The influence of learning on host plant preference in a significant phytopathogen vector, Diaphorina citri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri, vector ...

  19. An improved method of DNA extraction from Diaphorina citri for HLB detection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB) is a devastating disease of citrus that is transmitted by two citrus psyllids. Diaphorina citri transmits Candidatus Liberibacter asiaticus (Las) and Ca. L. americanus (Lam), and Trioza erytreae transmits Ca. L. africanus (Laf). Ca. Liberibacter species can be detected in DNA ex...

  20. Host-choice behavior of Diaphorina citri Kuwayama (Hemiptera: Psyllidae) under laboratory conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is the vector of huanglongbing (HLB), considered to be the most devastating disease of citrus worldwide. Knowledge of the ACP’s host-plant finding behavior aids in our understanding of the epidemiology of HLB and in designing experiments to ...

  1. Population dynamics and growth rates of endosymbionts during Diaphorina citri (Hemiptera, Liviidae) ontogeny.

    PubMed

    Dossi, Fabio Cleisto Alda; da Silva, Edney Pereira; Cônsoli, Fernando Luis

    2014-11-01

    The infection density of symbionts is among the major parameters to understand their biological effects in host-endosymbionts interactions. Diaphorina citri harbors two bacteriome-associated bacterial endosymbionts (Candidatus Carsonella ruddii and Candidatus Profftella armatura), besides the intracellular reproductive parasite Wolbachia. In this study, the density dynamics of the three endosymbionts associated with the psyllid D. citri was investigated by real-time quantitative PCR (qPCR) at different developmental stages. Bacterial density was estimated by assessing the copy number of the 16S rRNA gene for Carsonella and Profftella, and of the ftsZ gene for Wolbachia. Analysis revealed a continuous growth of the symbionts during host development. Symbiont growth and rate curves were estimated by the Gompertz equation, which indicated a negative correlation between the degree of symbiont-host specialization and the time to achieve the maximum growth rate (t*). Carsonella densities were significantly lower than those of Profftella at all host developmental stages analyzed, even though they both displayed a similar trend. The growth rates of Wolbachia were similar to those of Carsonella, but Wolbachia was not as abundant. Adult males displayed higher symbiont densities than females. However, females showed a much more pronounced increase in symbiont density as they aged if compared to males, regardless of the incorporation of symbionts into female oocytes and egg laying. The increased density of endosymbionts in aged adults differs from the usual decrease observed during host aging in other insect-symbiont systems.

  2. Endosymbiont hunting in the metagenome of Asian citrus psyllid (Diaphorina citri) (7th Annual SFAF Meeting, 2012)

    SciTech Connect

    Saha, Surya

    2012-06-01

    Surya Saha on "Endosymbiont hunting in the metagenome of Asian citrus psyllid (Diaphorina citri)" at the 2012 Sequencing, Finishing, Analysis in the Future Meeting held June 5-7, 2012 in Santa Fe, New Mexico.

  3. Endosymbiont hunting in the metagenome of Asian citrus psyllid (Diaphorina citri) (7th Annual SFAF Meeting, 2012)

    ScienceCinema

    Saha, Surya [Cornell University

    2016-07-12

    Surya Saha on "Endosymbiont hunting in the metagenome of Asian citrus psyllid (Diaphorina citri)" at the 2012 Sequencing, Finishing, Analysis in the Future Meeting held June 5-7, 2012 in Santa Fe, New Mexico.

  4. Insecticidal Suppression of Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae) Vector of Huanglongbing Pathogens

    PubMed Central

    Qureshi, Jawwad A.; Kostyk, Barry C.; Stansly, Philip A.

    2014-01-01

    Diaphorina citri vectors pathogens that cause ‘huanglongbing’ or citrus greening disease which poses a serious threat to citrus production worldwide. Vector suppression is critical to reduce disease spread. Efficacy is a main concern when choosing an insecticide. Insecticidal treatments of 49 products or 44 active ingredients (a.i) labeled or experimental were field tested between 2005–2013 as foliar sprays (250 treatments, 39 a.i) or soil applications (47 treatments, 9 a.i) to control D. citri in citrus. A combined effect of nymphal and adult suppression in response to sprays of 23 insecticides representing 9 modes of action (MoA) groups and 3 unknown MoA provided more than 90% reduction of adult D. citri over 24–68 days. Observable effects on nymphs were generally of shorter duration due to rapid maturation of flush. However, reduction of 76–100% nymphs or adults over 99–296 days was seen on young trees receiving drenches of the neonicotinoids imidacloprid, thiamethoxam or clothianidin (MoA 4A) and a novel anthranilic diamide, cyantraniliprole (MoA 28). Effective products identified for foliar sprays to control D. citri provide sufficient MoA groups for rotation to delay evolution of insecticide resistance by D. citri and other pests. However, cyantraniliprole is now the only available alternative for rotation with neonicotinoids in soil application to young trees. Sprays of up to eight of the most effective insecticides could be rotated over a year without repetition of any MoA and little or no recourse to neonicotinoids or cyantraniliprole, so important for protection of young trees. Other considerations effecting decisions of what and when to spray include prevalence of huanglongbing, pest pressure, pre-harvest intervals, overall budget, equipment availability, and conservation of beneficial arthropods. Examples of spray programs utilizing broad-spectrum and relatively selective insecticides are provided to improve vector management and may vary

  5. The effects of host, geographic origin, and gender on the thermal requirements of Diaphorina citri (Hemiptera: Psyllidae).

    PubMed

    Nava, Dori E; Gomez-Torres, Mariuxi L; Rodrigues, Marjorie D; Bento, José M S; Haddad, Marinéia L; Parra, José R P

    2010-04-01

    Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is the vector of the bacteria that causes citrus greening and is considered one of the world's most important citrus diseases. We examined how host, geographic region, and gender affect the thermal requirements of D. citri. The insects were reared in climatic chambers at constant temperatures of 18, 20, 22, 25, 28, 30, and 32 +/- 1 degrees C, 70 +/- 10% RH, and a 14 h photophase. Host plants for D. citri included orange (Citrus sinensis [Rutaceae]) varieties Pêra and Natal, the rootstock, Rungpur lime (C. limonia [Rutaceae]) and the natural host, Orange jessamine (Murraya paniculata [Rutaceae]). To study the influence of geographic origin on thermal requirements, we studied D. citri populations from Piracicaba, SP (warmer region) and Itapetininga, SP (cooler region). The duration and survival of the development stages and the duration of the total development (egg-adult) did not differ significantly on the different hosts, but it did vary with temperature. Nymphs of D. citri created on the different hosts have the same thermal requirements. The thermal requirements for this species collected from the two climate regions were identical; males and females also had the same thermal requirements.

  6. Better Together: Association With ‘Candidatus Liberibacter Asiaticus’ Increases the Reproductive Fitness of Its Insect Vector, Diaphorina citri (Hemiptera: Liviidae)

    PubMed Central

    Pelz-Stelinski, K. S.; Killiny, N.

    2016-01-01

    The duration of the evolutionary association between a pathogen and vector can be inferred based on the strength of their mutualistic interactions. A well-adapted pathogen is likely to confer some benefit or, at a minimum, exhibit low pathogenicity toward its host vector. Coevolution of the two toward a mutually beneficial association appears to have occurred between the citrus greening disease pathogen, Candidatus Liberibacter asiaticus (Las), and its insect vector, the Asian citrus psyllid, Diaphorina citri (Kuwayama). To better understand the dynamics facilitating transmission, we evaluated the effects of Las infection on the fitness of its vector. Diaphorina citri harboring Las were more fecund than their uninfected counterparts; however, their nymphal development rate and adult survival were comparatively reduced. The finite rate of population increase and net reproductive rate were both greater among Las-infected D. citri as compared with uninfected counterparts, indicating that overall population fitness of infected psyllids was improved given the greater number of offspring produced. Previous reports of transovarial transmission, in conjunction with increased fecundity and population growth rates of Las-positive D. citri found in the current investigation, suggest a long evolutionary relationship between pathogen and vector. The survival of Las-infected adult D. citri was lower compared with uninfected D. citri, which suggests that there may be a fitness trade-off in response to Las infection. A beneficial effect of a plant pathogen on vector fitness may indicate that the pathogen developed a relationship with the insect before secondarily moving to plants. PMID:27418697

  7. Differences in Stylet Sheath Occurrence and the Fibrous Ring (Sclerenchyma) between xCitroncirus Plants Relatively Resistant or Susceptible to Adults of the Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae)

    PubMed Central

    Ammar, El-Desouky; Richardson, Matthew L.; Abdo, Zaid; Hall, David G.; Shatters, Robert G.

    2014-01-01

    The Asian citrus psyllid (ACP, Diaphorina citri, Hemiptera: Liviidae), is the principal vector of the phloem-limited bacteria strongly associated with huanglongbing (HLB), the world’s most serious disease of citrus. Host plant resistance may provide an environmentally safe and sustainable method of controlling ACP and/or HLB. Two xCitroncirus accessions (hybrids of Poncirus trifoliata and Citrus spp.), that are relatively resistant (UN-3881) or relatively susceptible (Troyer-1459) to ACP adults with regard to adult longevity, were compared in relation to ACP feeding behavior and some structural features of the leaf midrib. The settling (putative feeding/probing) sites of ACP adults on various parts of the leaf were not influenced primarily by plant accession. However, fewer ACP stylet sheaths were found in the midrib and fewer stylet sheath termini reached the vascular bundle (phloem and/or xylem) in UN-3881 compared to Troyer-1459 plants. Furthermore, in midribs of UN-3881 leaves the fibrous ring (sclerenchyma) around the phloem was significantly wider (thicker) compared to that in midribs of Troyer-1459 leaves. Our data indicate that feeding and/or probing by ACP adults into the vascular bundle is less frequent in the more resistant (UN-3881) than in the more susceptible (Troyer-1459) accessions. Our results also suggest that the thickness of the fibrous ring may be a barrier to stylet penetration into the vascular bundle, which is important for successful ACP feeding on the phloem and for transmitting HLB-associated bacteria. These results may help in the development of citrus plants resistant to ACP, which in turn could halt or slow the spread of the HLB-associated bacteria by this vector. PMID:25343712

  8. Protein interaction networks at the host–microbe interface in Diaphorina citri, the insect vector of the citrus greening pathogen

    PubMed Central

    Chavez, J. D.; Johnson, R.; Hosseinzadeh, S.; Mahoney, J. E.; Mohr, J. P.; Robison, F.; Zhong, X.; Hall, D. G.; MacCoss, M.; Bruce, J.; Cilia, M.

    2017-01-01

    The Asian citrus psyllid (Diaphorina citri) is the insect vector responsible for the worldwide spread of ‘Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease. Developmental changes in the insect vector impact pathogen transmission, such that D. citri transmission of CLas is more efficient when bacteria are acquired by nymphs when compared with adults. We hypothesize that expression changes in the D. citri immune system and commensal microbiota occur during development and regulate vector competency. In support of this hypothesis, more proteins, with greater fold changes, were differentially expressed in response to CLas in adults when compared with nymphs, including insect proteins involved in bacterial adhesion and immunity. Compared with nymphs, adult insects had a higher titre of CLas and the bacterial endosymbionts Wolbachia, Profftella and Carsonella. All Wolbachia and Profftella proteins differentially expressed between nymphs and adults are upregulated in adults, while most differentially expressed Carsonella proteins are upregulated in nymphs. Discovery of protein interaction networks has broad applicability to the study of host–microbe relationships. Using protein interaction reporter technology, a D. citri haemocyanin protein highly upregulated in response to CLas was found to physically interact with the CLas coenzyme A (CoA) biosynthesis enzyme phosphopantothenoylcysteine synthetase/decarboxylase. CLas pantothenate kinase, which catalyses the rate-limiting step of CoA biosynthesis, was found to interact with a D. citri myosin protein. Two Carsonella enzymes involved in histidine and tryptophan biosynthesis were found to physically interact with D. citri proteins. These co-evolved protein interaction networks at the host–microbe interface are highly specific targets for controlling the insect vector responsible for the spread of citrus greening. PMID:28386418

  9. Repellent Activity of Botanical Oils against Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae)

    PubMed Central

    Kuhns, Emily H.; Martini, Xavier; Hoyte, Angel; Stelinski, Lukasz L.

    2016-01-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama, is the insect vector of the pathogen causing huanglongbing. We selected three botanical oils to evaluate behavioral activity against D. citri. In laboratory olfactometer assays, fir oil was repellent to D. citri females, while litsea and citronella oils elicited no response from D. citri females. In choice settling experiments, D. citri settled almost completely on control plants rather than on plants treated with fir oil at a 9.5 mg/day release rate. Therefore, we conducted field trials to determine if fir oil reduced D. citri densities in citrus groves. We found no repellency of D. citri from sweet orange resets that were treated with fir oil dispensers releasing 10.4 g/day/tree as compared with control plots. However, we found a two-week decrease in populations of D. citri as compared with controls when the deployment rate of these dispensers was doubled. Our results suggest that treatment of citrus with fir oil may have limited activity as a stand-alone management tool for D. citri and would require integration with other management practices. PMID:27429006

  10. Diaphorina citri (Hemiptera: Liviidae) responses to microcontroller-buzzer communication signals of potential use in vibration traps

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Monitoring of Diaphorina citri Kuwayama populations is an important component of efforts to reduce damage caused by huanglongbing, a devastating disease it vectors in citrus groves. Currently, D. citri is monitored primarily by unbaited sticky traps or visual inspection of trees. A potentially more ...

  11. Botanicals, selective insecticides, and predators to control Diaphorina citri (Hemiptera: Liviidae) in citrus orchards.

    PubMed

    Khan, Azhar A; Afzal, Muhammad; Qureshi, Jawwad A; Khan, Arif M; Raza, Abubakar M

    2014-12-01

    The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama vectors pathogens that cause huanglongbing (HLB) or citrus greening devastating and economically important disease present in most citrus growing regions. Young citrus shoots are required for psyllid reproduction and development. During winter citrus trees produce little or no new growth. Overwintering adults reproduce in spring on newly emerging shoots also attractive to other pests and beneficial insects. Botanicals and relatively selective insecticides could help to conserve beneficial insects and reduce pest resistance to insecticides. Sprays of Azadirachtin (Neem), Tropane (Datura), Spirotetramat, Spinetoram, and broad-spectrum Imidacloprid were evaluated to control ACP in spring and summer on 10-year-old "Kinow" Citrus reticulata Blanco trees producing new growth. Psyllid populations were high averaging 5-9 nymphs or adults per sample before treatment application. Nymphs or adults were significantly reduced to 0.5-1.5 per sample in all treatments for 3 weeks, average 61%-83% reduction. No significant reduction in ladybeetles Adalia bipunctata, Aneglei scardoni, Cheilomenes sexmaculata, and Coccinella septempunctata was observed. Syrphids, spiders and green lacewings were reduced in treated trees except with Tropane. Studies are warranted to assess impact of these predators on ACP and interaction with insecticides. Observed reduction in ACP populations may not be enough considering its reproductive potential and role in the spread of HLB. Follow-up sprays may be required to achieve additional suppression using rotations of different insecticides.

  12. Spatiotemporal dynamics of the Southern California Asian citrus psyllid (Diaphorina citri) invasion

    PubMed Central

    Thomas, Shyam M.; Simmons, Gregory S.; Grafton-Cardwell, Elizabeth E.; Daugherty, Mathew P.

    2017-01-01

    Biological invasions are governed by spatial processes that tend to be distributed in non-random ways across landscapes. Characterizing the spatial and temporal heterogeneities of the introduction, establishment, and spread of non-native insect species is a key aspect of effectively managing their geographic expansion. The Asian citrus psyllid (Diaphorina citri), a vector of the bacterium associated with huanglongbing (HLB), poses a serious threat to commercial and residential citrus trees. In 2008, D. citri first began expanding northward from Mexico into parts of Southern California. Using georeferenced D. citri occurrence data from 2008–2014, we sought to better understand the extent of the geographic expansion of this invasive vector species. Our objectives were to: 1) describe the spatial and temporal distribution of D. citri in Southern California, 2) identify the locations of statistically significant D. citri hotspots, and 3) quantify the dynamics of anisotropic spread. We found clear evidence that the spatial and temporal distribution of D. citri in Southern California is non-random. Further, we identified the existence of statistically significant hotspots of D. citri occurrence and described the anisotropic dispersion across the Southern California landscape. For example, the dominant hotspot surrounding Los Angeles showed rapid and strongly asymmetric spread to the south and east. Our study demonstrates the feasibility of quantitative invasive insect risk assessment with the application of a spatial epidemiology framework. PMID:28278188

  13. A “walker” tool to place Diaphorina citri (Hemiptera: Liviidae) adults at predetermined sites for bioassays of behavior in citrus (Sapindales: Rutacease) trees

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A walker tool was developed to assist placement of D. citri on citrus host trees in behavioral bioassays. The walker performs better than a commonly used paintbrush tool in the proportion of successful placements and in the reduction of jumps away from the citrus leaf, although it takes about two mi...

  14. Characterization of a Recombinant Cathepsin B-Like Cysteine Peptidase from Diaphorina citri Kuwayama (Hemiptera: Liviidae): A Putative Target for Control of Citrus Huanglongbing.

    PubMed

    Ferrara, Taíse Fernanda da Silva; Schneider, Vanessa Karine; Kishi, Luciano Takeshi; Carmona, Adriana Karaoglanovic; Alves, Marcio Fernando Madureira; Belasque-Júnior, Jose; Rosa, José César; Hunter, Wayne Brian; Henrique-Silva, Flávio; Soares-Costa, Andrea

    2015-01-01

    Huanglonbing (HLB) is one of the most destructive disease affecting citrus plants. The causal agent is associated with the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas) and the psyllid Diaphorina citri, vector of disease, that transmits the bacterium associated with HLB. The control of disease can be achieved by suppressing either the bacterium or the vector. Among the control strategies for HLB disease, one of the widely used consists in controlling the enzymes of the disease vector, Diaphorina citri. The insect Diaphorina citri belongs to the order Hemiptera, which frequently have cysteine peptidases in the gut. The importance of this class of enzymes led us to search for enzymes in the D. citri transcriptome for the establishment of alternatives strategies for HLB control. In this study, we reported the identification and characterization of a cathepsin B-like cysteine peptidase from D. citri (DCcathB). DCcathB was recombinantly expressed in Pichia pastoris, presenting a molecular mass of approximately 50 kDa. The enzyme hydrolyzed the fluorogenic substrate Z-F-R-AMC (Km = 23.5 μM) and the selective substrate for cathepsin B, Z-R-R-AMC (Km = 6.13 μM). The recombinant enzyme was inhibited by the cysteine protease inhibitors E64 (IC50 = 0.014 μM) and CaneCPI-4 (Ki = 0.05 nM) and by the selective cathepsin B inhibitor CA-074 (IC50 = 0.095 nM). RT-qPCR analysis revealed that the expression of the DCcathB in nymph and adult was approximately 9-fold greater than in egg. Moreover, the expression of this enzyme in the gut was 175-fold and 3333-fold higher than in the remaining tissues and in the head, respectively, suggesting that DCcathB can be a target for HLB control.

  15. Characterization of a Recombinant Cathepsin B-Like Cysteine Peptidase from Diaphorina citri Kuwayama (Hemiptera: Liviidae): A Putative Target for Control of Citrus Huanglongbing

    PubMed Central

    Kishi, Luciano Takeshi; Carmona, Adriana Karaoglanovic; Alves, Marcio Fernando Madureira; Belasque-Júnior, Jose; Rosa, José César; Hunter, Wayne Brian; Henrique-Silva, Flávio; Soares-Costa, Andrea

    2015-01-01

    Huanglonbing (HLB) is one of the most destructive disease affecting citrus plants. The causal agent is associated with the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas) and the psyllid Diaphorina citri, vector of disease, that transmits the bacterium associated with HLB. The control of disease can be achieved by suppressing either the bacterium or the vector. Among the control strategies for HLB disease, one of the widely used consists in controlling the enzymes of the disease vector, Diaphorina citri. The insect Diaphorina citri belongs to the order Hemiptera, which frequently have cysteine peptidases in the gut. The importance of this class of enzymes led us to search for enzymes in the D. citri transcriptome for the establishment of alternatives strategies for HLB control. In this study, we reported the identification and characterization of a cathepsin B-like cysteine peptidase from D. citri (DCcathB). DCcathB was recombinantly expressed in Pichia pastoris, presenting a molecular mass of approximately 50 kDa. The enzyme hydrolyzed the fluorogenic substrate Z-F-R-AMC (Km = 23.5 μM) and the selective substrate for cathepsin B, Z-R-R-AMC (Km = 6.13 μM). The recombinant enzyme was inhibited by the cysteine protease inhibitors E64 (IC50 = 0.014 μM) and CaneCPI-4 (Ki = 0.05 nM) and by the selective cathepsin B inhibitor CA-074 (IC50 = 0.095 nM). RT-qPCR analysis revealed that the expression of the DCcathB in nymph and adult was approximately 9-fold greater than in egg. Moreover, the expression of this enzyme in the gut was 175-fold and 3333-fold higher than in the remaining tissues and in the head, respectively, suggesting that DCcathB can be a target for HLB control. PMID:26717484

  16. Citrus tristeza virus-based RNAi in citrus plants induces gene silencing in Diaphorina citri, a phloem-sap sucking insect vector of citrus greening disease (Huanglongbing).

    PubMed

    Hajeri, Subhas; Killiny, Nabil; El-Mohtar, Choaa; Dawson, William O; Gowda, Siddarame

    2014-04-20

    A transient expression vector based on Citrus tristeza virus (CTV) is unusually stable. Because of its stability it is being considered for use in the field to control Huanglongbing (HLB), which is caused by Candidatus Liberibacter asiaticus (CLas) and vectored by Asian citrus psyllid, Diaphorina citri. In the absence of effective control strategies for CLas, emphasis has been on control of D. citri. Coincident cohabitation in phloem tissue by CLas, D. citri and CTV was exploited to develop a novel method to mitigate HLB through RNA interference (RNAi). Since CTV has three RNA silencing suppressors, it was not known if CTV-based vector could induce RNAi in citrus. Yet, expression of sequences targeting citrus phytoene desaturase gene by CTV-RNAi resulted in photo-bleaching phenotype. CTV-RNAi vector, engineered with truncated abnormal wing disc (Awd) gene of D. citri, induced altered Awd expression when silencing triggers ingested by feeding D. citri nymphs. Decreased Awd in nymphs resulted in malformed-wing phenotype in adults and increased adult mortality. This impaired ability of D. citri to fly would potentially limit the successful vectoring of CLas bacteria between citrus trees in the grove. CTV-RNAi vector would be relevant for fast-track screening of candidate sequences for RNAi-mediated pest control.

  17. Double-Stranded RNA Uptake through Topical Application, Mediates Silencing of Five CYP4 Genes and Suppresses Insecticide Resistance in Diaphorina citri

    PubMed Central

    Killiny, Nabil; Hajeri, Subhas; Tiwari, Siddharth; Gowda, Siddarame; Stelinski, Lukasz L.

    2014-01-01

    Silencing of genes through RNA interference (RNAi) in insects has gained momentum during the past few years. RNAi has been used to cause insect mortality, inhibit insect growth, increase insecticide susceptibility, and prevent the development of insecticide resistance. We investigated the efficacy of topically applied dsRNA to induce RNAi for five Cytochrome P450 genes family 4 (CYP4) in Diaphorina citri. We previously reported that these CYP4 genes are associated with the development of insecticide resistance in D. citri. We targeted five CYP4 genes that share a consensus sequence with one dsRNA construct. Quantitative PCR confirmed suppressed expression of the five CYP4 genes as a result of dsRNA topically applied to the thoracic region of D. citri when compared to the expression levels in a control group. Western blot analysis indicated a reduced signal of cytochrome P450 proteins (45 kDa) in adult D. citri treated with the dsRNA. In addition, oxidase activity and insecticide resistance were reduced for D. citri treated with dsRNA that targeted specific CYP4 genes. Mortality was significantly higher in adults treated with dsRNA than in adults treated with water. Our results indicate that topically applied dsRNA can penetrate the cuticle of D. citri and induce RNAi. These results broaden the scope of RNAi as a mechanism to manage pests by targeting a broad range of genes. The results also support the application of RNAi as a viable tool to overcome insecticide resistance development in D. citri populations. However, further research is needed to develop grower-friendly delivery systems for the application of dsRNA under field conditions. Considering the high specificity of dsRNA, this tool can also be used for management of D. citri by targeting physiologically critical genes involved in growth and development. PMID:25330026

  18. Effects of atmospheric pressure trends on calling, mate-seeking, and phototaxis of Diaphorina citri (Hemiptera: Liviidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insects and other animals sometimes modify behavior in response to changes in atmospheric pressure, an environmental cue that can provide warning of potentially injurious windy and rainy weather. To determine if Diaphorina citri (Hemiptera: Liviidae) calling, mate-seeking, and phototaxis behaviors w...

  19. Field releases in Florida of Diaphorencyrtus aligarhensis (Hymenoptera: Encyrtidae), an endoparasitoid of Diaphorina citri (Homoptera: Psyllidae) from mainland China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri, is a critically important citrus pest in the United States because it vectors the pathogen responsible for citrus greening disease (huanglongbing). The psyllid is attacked in Asia by the encyrtid parasitoid Diaphorencyrtus aligarhensis, and it would be de...

  20. Effects on Asian Citrus Psyllid (Diaphorina citri Kuwayama) feeding behavior of fenpropathrin and chlorpyrifos within 24 hours of application

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB), also known as citrus greening disease, is one of the most destructive diseases affecting citrus production. The phloem-limited bacterium associated with HLB is transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). One component of HLB managem...

  1. Detection of Candidatus Liberibacter asiaticus in Diaphorina citri and its importance in the management of Citrus Huanglongbing in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus huanglongbing (HLB or citrus greening) is a highly destructive disease that has been spreading in both Florida and Brazil. Its psyllid vector, Diaphorina citri, has spread to Texas and Mexico thus threatening the future of citrus production elsewhere in North America. Even though, sensitive d...

  2. Toxicity of insecticidal soaps to the Asian citrus psyllid (Diaphorina citri) and two of its natural enemies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insecticidal soaps (hereafter “soaps”) are labeled for use by homeowners and also can be used in citrus grown for the organic market. Soaps control some insect pests and therefore might be an alternative to conventional pesticides for control of the Asian citrus psyllid, Diaphorina citri Kuwayama (...

  3. Antennal and behavioral response of the Asian citrus psyllid (Diaphorina citri Kuwayama) to degradation products of citrus volatiles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) vectors the bacterial causal pathogen of the deadly citrus disease, Huanglongbing (citrus greening) which is a major threat to citrus industry worldwide. We studied antennal and behavioral responses to principal components of head...

  4. The Genetic Structure of an Invasive Pest, the Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae)

    PubMed Central

    Guidolin, Aline S.; Fresia, Pablo; Cônsoli, Fernando L.

    2014-01-01

    The Asian citrus psyllid Diaphorina citri is currently the major threat to the citrus industry as it is the vector of Candidatus Liberibacter, the causal agent of huanglongbing disease (HLB). D. citri is native to Asia and now colonizes the Americas. Although it has been known in some countries for a long time, invasion routes remain undetermined. There are no efficient control methods for the HLB despite the intensive management tools currently in use. We investigated the genetic variability and structure of populations of D. citri to aid in the decision making processes toward sustainable management of this species/disease. We employed different methods to quantify and compare the genetic diversity and structure of D. citri populations among 36 localities in Brazil, using an almost complete sequence of the cytochrome oxidase I (COI) gene. Our analyses led to the identification of two geographically and genetically structured groups. The indices of molecular diversity pointed to a recent population expansion, and we discuss the role of multiple invasion events in this scenario. We also argue that such genetic diversity and population structure may have implications for the best management strategies to be adopted for controlling this psyllid and/or the disease it vectors in Brazil. PMID:25545788

  5. Morphometric comparisons of Diaphorina citri (Hemiptera: Liviidae) populations from Iran, USA and Pakistan

    PubMed Central

    Lashkari, Mohammadreza; Hentz, Matthew G.

    2015-01-01

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), vector of citrus greening disease pathogen, Huanglongbing (HLB), is considered the most serious pest of citrus in the world. Prior molecular based studies have hypothesized a link between the D. citri in Iran and the USA (Florida). The purpose of this study was to collect morphometric data from D. citri populations from Iran (mtCOI haplotype-1), Florida (mtCOI haplotype-1), and Pakistan (mtCOI haplotype-6), to determine whether different mtCOI haplotypes have a relationship to a specific morphometric variation. 240 samples from 6 ACP populations (Iran—Jiroft, Chabahar; Florida—Ft. Pierce, Palm Beach Gardens, Port St. Lucie; and Pakistan—Punjab) were collected for comparison. Measurements of 20 morphological characters were selected, measured and analysed using ANOVA and MANOVA. The results indicate differences among the 6 ACP populations (Wilks’ lambda = 0.0376, F = 7.29, P < 0.0001). The body length (BL), circumanal ring length (CL), antenna length (AL), forewing length (WL) and Rs vein length of forewing (RL) were the most important characters separating the populations. The cluster analysis showed that the Iran and Florida populations are distinct from each other but separate from the Pakistan population. Thus, three subgroups can be morphologically discriminated within D. citri species in this study, (1) Iran, (2) USA (Florida) and (3) Pakistan population. Morphometric comparisons provided further resolution to the mtCOI haplotypes and distinguished the Florida and Iranian populations. PMID:26038715

  6. Antennal and Abdominal Transcriptomes Reveal Chemosensory Genes in the Asian Citrus Psyllid, Diaphorina citri

    PubMed Central

    Wu, Zhongzhen; Zhang, He; Bin, Shuying; Chen, Lei; Han, Qunxin; Lin, Jintian

    2016-01-01

    The Asian citrus psyllid, Diaphorina citri is the principal vector of the highly destructive citrus disease called Huanglongbing (HLB) or citrus greening, which is a major threat to citrus cultivation worldwide. More effective pest control strategies against this pest entail the identification of potential chemosensory proteins that could be used in the development of attractants or repellents. However, the molecular basis of olfaction in the Asian citrus psyllid is not completely understood. Therefore, we performed this study to analyze the antennal and abdominal transcriptome of the Asian citrus psyllid. We identified a large number of transcripts belonging to nine chemoreception-related gene families and compared their expression in male and female adult antennae and terminal abdomen. In total, 9 odorant binding proteins (OBPs), 12 chemosensory proteins (CSPs), 46 odorant receptors (ORs), 20 gustatory receptors (GRs), 35 ionotropic receptors (IRs), 4 sensory neuron membrane proteins (SNMPs) and 4 different gene families encoding odorant-degrading enzymes (ODEs): 80 cytochrome P450s (CYPs), 12 esterase (ESTs), and 5 aldehyde dehydrogenases (ADE) were annotated in the D. citri antennal and abdominal transcriptomes. Our results revealed that a large proportion of chemosensory genes exhibited no distinct differences in their expression patterns in the antennae and terminal abdominal tissues. Notably, RNA sequencing (RNA-seq) data and quantitative real time-PCR (qPCR) analyses showed that 4 DictOBPs, 4 DictCSPs, 4 DictIRs, 1 DictSNMP, and 2 DictCYPs were upregulated in the antennae relative to that in terminal abdominal tissues. Furthermore, 2 DictOBPs (DictOBP8 and DictOBP9), 2 DictCSPs (DictOBP8 and DictOBP12), 4 DictIRs (DictIR3, DictIR6, DictIR10, and DictIR35), and 1 DictCYP (DictCYP57) were expressed at higher levels in the male antennae than in the female antennae. Our study provides the first insights into the molecular basis of chemoreception in this insect

  7. Antennal and Abdominal Transcriptomes Reveal Chemosensory Genes in the Asian Citrus Psyllid, Diaphorina citri.

    PubMed

    Wu, Zhongzhen; Zhang, He; Bin, Shuying; Chen, Lei; Han, Qunxin; Lin, Jintian

    2016-01-01

    The Asian citrus psyllid, Diaphorina citri is the principal vector of the highly destructive citrus disease called Huanglongbing (HLB) or citrus greening, which is a major threat to citrus cultivation worldwide. More effective pest control strategies against this pest entail the identification of potential chemosensory proteins that could be used in the development of attractants or repellents. However, the molecular basis of olfaction in the Asian citrus psyllid is not completely understood. Therefore, we performed this study to analyze the antennal and abdominal transcriptome of the Asian citrus psyllid. We identified a large number of transcripts belonging to nine chemoreception-related gene families and compared their expression in male and female adult antennae and terminal abdomen. In total, 9 odorant binding proteins (OBPs), 12 chemosensory proteins (CSPs), 46 odorant receptors (ORs), 20 gustatory receptors (GRs), 35 ionotropic receptors (IRs), 4 sensory neuron membrane proteins (SNMPs) and 4 different gene families encoding odorant-degrading enzymes (ODEs): 80 cytochrome P450s (CYPs), 12 esterase (ESTs), and 5 aldehyde dehydrogenases (ADE) were annotated in the D. citri antennal and abdominal transcriptomes. Our results revealed that a large proportion of chemosensory genes exhibited no distinct differences in their expression patterns in the antennae and terminal abdominal tissues. Notably, RNA sequencing (RNA-seq) data and quantitative real time-PCR (qPCR) analyses showed that 4 DictOBPs, 4 DictCSPs, 4 DictIRs, 1 DictSNMP, and 2 DictCYPs were upregulated in the antennae relative to that in terminal abdominal tissues. Furthermore, 2 DictOBPs (DictOBP8 and DictOBP9), 2 DictCSPs (DictOBP8 and DictOBP12), 4 DictIRs (DictIR3, DictIR6, DictIR10, and DictIR35), and 1 DictCYP (DictCYP57) were expressed at higher levels in the male antennae than in the female antennae. Our study provides the first insights into the molecular basis of chemoreception in this insect

  8. Characterization of the voltage-gated sodium channel of the Asian citrus psyllid, Diaphorina citri.

    PubMed

    Liu, Bin; Coy, Monique R; Wang, Jin-Jun; Stelinski, Lukasz L

    2017-02-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an important insect pest of citrus. It is the vector of 'Candidatus' Liberibacter asiaticus, a phloem-limited bacterium that infects citrus, resulting in the disease Huanglongbing (HLB). Disease management relies heavily on suppression of D. citri populations with insecticides, including pyrethroids. In recent annual surveys to monitor insecticide resistance, reduced susceptibility to fenpropathrin was identified in several field populations of D. citri. The primary target of pyrethroids is the voltage-gated sodium channel (VGSC). The VGSC is prone to target-site insensitivity because of mutations that either reduce pyrethroid binding and/or alter gating kinetics. These mutations, known as knockdown resistance or kdr, have been reported in a wide diversity of arthropod species. Alternative splicing, in combination with kdr mutations, has been also associated with reduced pyrethroid efficacy. Here we report the molecular characterization of the VGSC in D. citri along with a survey of alternative splicing across developmental stages of this species. Previous studies demonstrated that D. citri has an exquisite enzymatic arsenal to detoxify insecticides resulting in reduced efficacy. The results from the current investigation demonstrate that target-site insensitivity is also a potential basis for insecticide resistance to pyrethroids in D. citri. The VGSC sequence and its molecular characterization should facilitate early elucidation of the underlying cause of an established case of resistance to pyrethroids. This is the first characterization of a VGSC from a hemipteran to this level of detail, with the majority of the previous studies on dipterans and lepidopterans.

  9. Incidence of invasive Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae) and its introduced parasitoid Tamarixia radiata (Hymenoptera: Eulophidae) in Florida citrus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae) vectors the bacterium Candidatus Liberibacter asiaticus, one of the causal organisms of Huanglongbing or citrus greening, a devastating disease of citrus. A eulophid parasitoid, Tamarixia radiata Waterson, was imported ...

  10. Multimodal cues drive host-plant assessment in Asian citrus psyllid (Diaphorina citri).

    PubMed

    Patt, Joseph M; Meikle, William G; Mafra-Neto, Agenor; Sétamou, Mamoudou; Mangan, Robert; Yang, Chenghai; Malik, Nasir; Adamczyk, John J

    2011-12-01

    Asian citrus psyllid (Diaphorina citri) transmits the causal agent of Huanglongbing, a devastating disease of citrus trees. In this study we measured behavioral responses of D. citri to combinations of visual, olfactory, and gustatory stimuli in test arenas. Stimuli were presented to the psyllids in droplets or lines of an emulsified wax formulation in two different arena types in no-choice tests. First, when placed on a colored ring situated halfway between the center and perimeter of a petri dish, D. citri spent more time on yellow versus gray rings; however, this response disappeared when either gray or yellow wax droplets were applied. When the psyllids were presented with droplets scented with terpenes, the response to both scent and color was increased. The addition of a dilute (≍0.1 M) sucrose solution to the wax droplets increased the magnitude of D. citri responses. Next, groups of D. citri were placed on plastic laboratory film covering a sucrose solution, to mimic a leaf surface. Test stimuli were presented via two 'midribs' made from lines of emulsified wax formulation. Probing levels were measured as a function of color saturation and scent composition, and concentration. The test scents were based on qualitatively major volatiles emitted by Murraya paniculata (L.) Jack, Citrus aurantifolia (Christm.) Swingle, and C. sinensis (L.) Osbeck. The highest probing response was observed on the middle concentration (20-μl scent/10 ml wax formulation) of the C. aurantifolia-scented wax lines. Results indicate that there are interactive effects between the different sensory modalities in directing host-plant assessment behavior.

  11. Overview of worldwide diversity of Diaphorina citri Kuwayama mitochondrial cytochrome oxidase 1 haplotypes: two Old World lineages and a New World invasion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We utilized a Bayesian phylogenetic technique to resolve global relationships of Diaphorina citri populations. This is the first global phylogenetic study of D. citri. New mitochondrial primers were designed from an EST library and an 821 base pair region of the COI was amplified and sequenced. The ...

  12. Incidence of huanglongbing-associated ‘Candidatus Liberibacter Asiaticus’ in Diaphorina citri (Hemiptera: Psyllidae) collected from plants for sale in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri Kuwayama, was reported for the first time in Florida in June 1998, and huanglongbing (HLB, citrus greening), vectored by D. citri, was detected in Florida for the first time in Aug 2005. In Florida, the only known HLB pathogen is ‘Candidatus Liberibacter as...

  13. Sequencing and annotation of the Wolbachia endosymbiont of Diaphorina citri by the CG-HLB genome resources group reveals candidate sources of interaction with the insect host

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diaphorina citri (Hemiptera: Psyllidae), the Asian citrus psyllid, is the vector of Ca. Liberibacter asiaticus, the causal agent of huanglongbing. The D. citri metagenome has been completed to gain a better understanding of the biology of this organism and the potential roles of other psyllid bacter...

  14. Living on the Edges: Spatial Niche Occupation of Asian Citrus Psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), in Citrus Groves

    PubMed Central

    2015-01-01

    The spatial niche occupation of the Asian citrus psyllid, Diaphorina citri Kuwayama, 1908, was evaluated to determine its field colonization and food resource exploitation strategies in citrus groves. Mature grapefruit and sweet orange groves were surveyed as part of an area-wide program in 2009–2010 to determine D. citri population densities and between-tree distribution. In both cultivars, significantly more psyllids were found on perimeter trees throughout the study period suggesting a strong edge effect in D. citri distribution in the groves. D. citri densities and infestation levels gradually declined from the edge to the center of grove. Higher numbers of D. citri were recorded on trees located on the east and south sides of the groves than those on the west and north sides. Citrus groves located at the outer edge of the study with at least one side non-surrounded to other citrus groves harbored significantly more D. citri than groves located within the block cluster and entirely surrounded by other groves. In detailed field studies during 2012, infestation of D. citri started from border trees in the grove where possibly one generation is completed before inner trees become infested. In addition, psyllid densities decreased significantly with increasing distance from the grove edge. Using the selection index, D citri exhibited a strong niche occupation preference for border trees. PMID:26193111

  15. Diverse Array of New Viral Sequences Identified in Worldwide Populations of the Asian Citrus Psyllid (Diaphorina citri) Using Viral Metagenomics

    PubMed Central

    Nouri, Shahideh; Salem, Nidá; Nigg, Jared C.

    2015-01-01

    ABSTRACT The Asian citrus psyllid, Diaphorina citri, is the natural vector of the causal agent of Huanglongbing (HLB), or citrus greening disease. Together; HLB and D. citri represent a major threat to world citrus production. As there is no cure for HLB, insect vector management is considered one strategy to help control the disease, and D. citri viruses might be useful. In this study, we used a metagenomic approach to analyze viral sequences associated with the global population of D. citri. By sequencing small RNAs and the transcriptome coupled with bioinformatics analysis, we showed that the virus-like sequences of D. citri are diverse. We identified novel viral sequences belonging to the picornavirus superfamily, the Reoviridae, Parvoviridae, and Bunyaviridae families, and an unclassified positive-sense single-stranded RNA virus. Moreover, a Wolbachia prophage-related sequence was identified. This is the first comprehensive survey to assess the viral community from worldwide populations of an agricultural insect pest. Our results provide valuable information on new putative viruses, some of which may have the potential to be used as biocontrol agents. IMPORTANCE Insects have the most species of all animals, and are hosts to, and vectors of, a great variety of known and unknown viruses. Some of these most likely have the potential to be important fundamental and/or practical resources. In this study, we used high-throughput next-generation sequencing (NGS) technology and bioinformatics analysis to identify putative viruses associated with Diaphorina citri, the Asian citrus psyllid. D. citri is the vector of the bacterium causing Huanglongbing (HLB), currently the most serious threat to citrus worldwide. Here, we report several novel viral sequences associated with D. citri. PMID:26676774

  16. Insecticide sprays, natural enemy assemblages and predation on Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae).

    PubMed

    Monzo, C; Qureshi, J A; Stansly, P A

    2014-10-01

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is considered a key citrus pest due to its role as vector of 'huanglongbing' (HLB) or citrus greening, probably the most economically damaging disease of citrus. Insecticidal control of the vector is still considered a cornerstone of HLB management to prevent infection and to reduce reinoculation of infected trees. The severity of HLB has driven implementation of intensive insecticide programs against ACP with unknown side effects on beneficial arthropod fauna in citrus agroecosystems. We evaluated effects of calendar sprays directed against this pest on natural enemy assemblages and used exclusion to estimate mortality they imposed on ACP populations in citrus groves. Predator exclusion techniques were used on nascent colonies of D. citri in replicated large untreated and sprayed plots of citrus during the four major flushing periods over 2 years. Population of spiders, arboreal ants and ladybeetles were independently assessed. Monthly sprays of recommended insecticides for control of ACP, adversely affected natural enemy populations resulting in reduced predation on ACP immature stages, especially during the critical late winter/early spring flush. Consequently, projected growth rates of the ACP population were greatest where natural enemies had been adversely affected by insecticides. Whereas, this result does not obviate the need for insecticidal control of ACP, it does indicate that even a selective regimen of sprays can impose as yet undetermined costs in terms of reduced biological control of this and probably other citrus pests.

  17. Two-Spotted Ladybeetle Adalia bipunctata L. (Coleoptera: Coccinellidae): A Commercially Available Predator to Control Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae)

    PubMed Central

    Afzal, Muhammad; Stansly, Philip A.

    2016-01-01

    The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is an economically important pest of citrus because it serves as a vector of the causal pathogens of huanglongbing (HLB) also known as citrus greening disease. The increased use of insecticides for control of D. citri negatively impacts several natural enemies including some effective ladybeetle species which are not available commercially. The two-spotted ladybeetle, Adalia bipunctata (Coleoptera: Coccinellidae) is found in some crop and forest ecosystems of Asia, Europe and North America and available commercially. It is known to attack aphids and mealybugs but there are no published records of feeding on psyllids. We evaluated suitability and preference of A. bipunctata for nymphs of D. citri compared to corn leaf aphid Rhopalosiphum maidis (Hemiptera: Aphididae) a global pest of cereal crops and prey for many predaceous insects. We also compared development and reproduction of A. bipunctata on these two species with frozen eggs of the Mediterranean flour moth Ephestia kuehniella (Lepidoptera: Pyralidae) at 25°C. Initially, more D. citri than R. maidis nymphs were consumed in the no-choice tests although final consumption by larva and adult of A. bipunctata did not differ in the choice and no-choice tests. Larval development was prolonged by one day on D. citri compared to R. maidis nymphs but did not differ between either of these diets and E. kuehniella. Larval survival to adult averaged 93–100% and was not impacted by diet. Adult life span did not differ between diets although those on D. citri and R. maidis nymphs weighed less and produced fewer but more fertile eggs than on E. kuehniella eggs. Significant reduction of D. citri nymphs averaging 54% was observed in colonies caged with adult A. bipunctata on field planted citrus. R° (net reproductive rate) was least for beetles fed R. maidis, but otherwise there were no significant differences in demographic parameters. Successful

  18. Survey of Endosymbionts in the Diaphorina citri Metagenome and Assembly of a Wolbachia wDi Draft Genome

    PubMed Central

    Saha, Surya; Hunter, Wayne B.; Reese, Justin; Morgan, J. Kent; Marutani-Hert, Mizuri; Huang, Hong; Lindeberg, Magdalen

    2012-01-01

    Diaphorina citri (Hemiptera: Psyllidae), the Asian citrus psyllid, is the insect vector of Ca. Liberibacter asiaticus, the causal agent of citrus greening disease. Sequencing of the D. citri metagenome has been initiated to gain better understanding of the biology of this organism and the potential roles of its bacterial endosymbionts. To corroborate candidate endosymbionts previously identified by rDNA amplification, raw reads from the D. citri metagenome sequence were mapped to reference genome sequences. Results of the read mapping provided the most support for Wolbachia and an enteric bacterium most similar to Salmonella. Wolbachia-derived reads were extracted using the complete genome sequences for four Wolbachia strains. Reads were assembled into a draft genome sequence, and the annotation assessed for the presence of features potentially involved in host interaction. Genome alignment with the complete sequences reveals membership of Wolbachia wDi in supergroup B, further supported by phylogenetic analysis of FtsZ. FtsZ and Wsp phylogenies additionally indicate that the Wolbachia strain in the Florida D. citri isolate falls into a sub-clade of supergroup B, distinct from Wolbachia present in Chinese D. citri isolates, supporting the hypothesis that the D. citri introduced into Florida did not originate from China. PMID:23166822

  19. Species clarification of Isaria isolates used as biocontrol agents against Diaphorina citri (Hemiptera: Liviidae) in Mexico.

    PubMed

    Gallou, Adrien; Serna-Domínguez, María G; Berlanga-Padilla, Angélica M; Ayala-Zermeño, Miguel A; Mellín-Rosas, Marco A; Montesinos-Matías, Roberto; Arredondo-Bernal, Hugo C

    2016-03-01

    Entomopathogenic fungi belonging to the genus Isaria (Hypocreales: Cordycipitaceae) are promising candidates for microbial control of insect pests. Currently, the Mexican government is developing a biological control program based on extensive application of Isaria isolates against Diaphorina citri (Hemiptera: Liviidae), a vector of citrus huanglongbing disease. Previous research identified three promising Isaria isolates (CHE-CNRCB 303, 305, and 307; tentatively identified as Isaria fumosorosea) from Mexico. The goal of this work was to obtain a complete morphological and molecular characterization of these isolates. Comparative analysis of morphology established that the isolates showed similar characteristics to Isaria javanica. Multi-gene analysis confirmed the morphological identification by including the three isolates within the I. javanica clade. Additionally, this work demonstrated the misidentifications of three other Isaria isolates (CHE-CNRCB 310 and 324: I. javanica, formerly I. fumosorosea; CHE-CNRCB 393: I. fumosorosea, formerly Isaria farinosa), underlying the need for a full and correct characterization of an isolate before developing a biological control program. Finally, the inter-simple sequence repeat (ISSR) genotyping method revealed that the CHE-CNRCB 303, 305, and 307 isolates belong to three different genotypes. This result indicates that ISSR markers could be used as a tool to monitor their presence in field conditions.

  20. Exposure to Guava Affects Citrus Olfactory Cues and Attractiveness to Diaphorina citri (Hemiptera: Psyllidae).

    PubMed

    Barman, Jagadish Chandra; Campbell, Stuart A; Zeng, Xinnian

    2016-06-01

    Intercropping can reduce agricultural pest incidence, and represents an important sustainable alternative to conventional pest control methods. Understanding the ecological mechanisms for intercropping could help optimize its use, particularly in tropical systems which present a large number of intercropping possibilities. Citrus is threatened worldwide by greening disease (huanglongbing, HLB) vectored by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Control of HLB and citrus psyllid can be partially achieved through intercropping with guava, Psidium guajava L., but the mechanisms remain unclear. We tested the hypothesis that guava olfactory cues affect psyllid behavior by altering the attractiveness of citrus through plant-plant interactions. In choice and no-choice cage experiments, psyllid settlement was reduced on citrus shoots that had been exposed to guava shoot odors for at least 2 h. In Y-tube olfactometer experiments, psyllids oriented to odors of unexposed, compared with guava-exposed, citrus shoots. These behavioral results indicate that a mechanism for the success of guava intercropping for sustainable, ecological disease management may be the indirect effect of guava on citrus attractiveness.

  1. Effective use of neonicotinoids for protection of citrus seedlings from invasion by Diaphorina citri (Hemiptera: Psyllidae).

    PubMed

    Ichinose, Katsuya; Bang, Doan V; Tuan, Do H; Dien, Le Q

    2010-02-01

    The application of insecticides to control Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is a principal component of the current management for citrus greening disease or Huanglongbing. It is recommended that growers apply systemic insecticides such as imidacloprid and thiamethoxam every 2 mo after seedling planting, but this practice renders the seedlings insecticide-free and vulnerable to psyllid infestation in the first 2 mo. We evaluated the risk of vector invasion during this period from field studies of the psyllid in five new king mandarin, Citrus nobilis Loureiro, orchards in the Mekong Delta region of Vietnam. The first psyllids were found after the first 2 wk, and 2 to 60% of the trees were finally infested by psyllids during the 2 mo. The risk of psyllid invasion could be significantly reduced if the insecticide were applied to seedlings before planting. Three systemics, imidacloprid, thiamethoxam, and clothianidin, were examined in both a net house and in the field to assess how quickly they could be effective after application and how long their efficacy could continue. High psyllid mortality >80% was attained in 10 d after application, and this level was maintained for 90 d in the net house and for 60 d in the field. Based on these results, we propose the effective use of neonicotinoids for protection of citrus seedlings against invasive psyllids during the first 2 mo after planting.

  2. Geographic distribution of habitat, development, and population growth rates of the Asian citrus psyllid, Diaphorina citri, in Mexico.

    PubMed

    López-Collado, José; Isabel López-Arroyo, J; Robles-García, Pedro L; Márquez-Santos, Magdalena

    2013-01-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is an introduced pest in Mexico and a vector of huanglongbing, a lethal citrus disease. Estimations of the habitat distribution and population growth rates of D. citri are required to establish regional and areawide management strategies and can be used as a pest risk analysis tools. In this study, the habitat distribution of D. citri in Mexico was computed with MaxEnt, an inductive, machine-learning program that uses bioclimatic layers and point location data. Geographic distributions of development and population growth rates were determined by fitting a temperature-dependent, nonlinear model and projecting the rates over the target area, using the annual mean temperature as the predictor variable. The results showed that the most suitable regions for habitat of D. citri comprise the Gulf of Mexico states, Yucatán Peninsula, and areas scattered throughout the Pacific coastal states. Less suitable areas occurred in northern and central states. The most important predictor variables were related to temperature. Development and growth rates had a distribution wider than habitat, reaching some of the northern states of México. Habitat, development, and population growth rates were correlated to each other and with the citrus producing area. These relationships indicated that citrus producing states are within the most suitable regions for the occurrence, development, and population growth of D. citri, therefore increasing the risk of huanglongbing dispersion.

  3. Geographic Distribution of Habitat, Development, and Population Growth Rates of the Asian Citrus Psyllid, Diaphorina citri, in Mexico

    PubMed Central

    López-Collado, José; Isabel López-Arroyo, J.; Robles-García, Pedro L.; Márquez-Santos, Magdalena

    2013-01-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is an introduced pest in Mexico and a vector of huanglongbing, a lethal citrus disease. Estimations of the habitat distribution and population growth rates of D. citri are required to establish regional and areawide management strategies and can be used as a pest risk analysis tools. In this study, the habitat distribution of D. citri in Mexico was computed with MaxEnt, an inductive, machine-learning program that uses bioclimatic layers and point location data. Geographic distributions of development and population growth rates were determined by fitting a temperature-dependent, nonlinear model and projecting the rates over the target area, using the annual mean temperature as the predictor variable. The results showed that the most suitable regions for habitat of D. citri comprise the Gulf of Mexico states, Yucatán Peninsula, and areas scattered throughout the Pacific coastal states. Less suitable areas occurred in northern and central states. The most important predictor variables were related to temperature. Development and growth rates had a distribution wider than habitat, reaching some of the northern states of México. Habitat, development, and population growth rates were correlated to each other and with the citrus producing area. These relationships indicated that citrus producing states are within the most suitable regions for the occurrence, development, and population growth of D. citri, therefore increasing the risk of huanglongbing dispersion. PMID:24735280

  4. Characterization of a recombinant Cathepsin B-Like cysteine peptidase from Diaphorina citri Kuwayama (Hemiptera: Liviidae): A putative target control of citrus huanglongbing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB) is one of the most destructive disease affecting citrus plants. The causal agent is associated with the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas) spread by the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae). Among the control strategies for H...

  5. RNAi-based strategy for Asian citrus psyllid (Diaphorina citri) Control: A method to reduce the spread of citrus greening disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus greening disease is a serious bacterial disease of citrus worldwide and is vectored by the Asian citrus pysllid (Diaphorina Citri). The only effective control strategy includes vigorous control of the psyllid, primarily through heavy reliance on pesticides. As a more sustainable and environm...

  6. A rapid field detection system for citrus huanglongbing associated ‘Candidatus Liberibacter asiaticus’ from the psyllid vector, diaphorina citri kuwayama and its implications in disease management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report the development of an affordable detection kit for the detection of ‘Candidatus Liberibacter asiaticus’ (Las) from the psyllid vector, Diaphorina citri, which can provide real time test results in the field or field laboratory within 30-40 minutes without the need for expensive laboratory ...

  7. Detection of citrus huanglongbing-associated ‘Candidatus Liberibacter asiaticus’ in citrus and Diaphorina citri in Pakistan, season variability, and implications for disease management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report the detection of the huanglongbing (HLB)-associated bacterium ‘Candidatus Liberibacter asiaticus’ from both plants and insects in Pakistan and the seasonal variability in the numbers of ‘Ca. L. asiaticus’-positive psyllid vector, Diaphorina citri. Our studies showed that ‘Ca. L. asiaticus’...

  8. Titers of 'Ca. Liberibacter asiaticus' in Murraya paniculata and Murraya-reared Diaphorina citri are much lower than in citrus and citrus-reared psyllids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing, one of the most devastating diseases of citrus, is associated with the bacterium Candidatus Liberibacter asiaticus vectored by the Asian citrus psyllid, Diaphorina citri, in North America. Murraya paniculata is a common ornamental plant that is an alternate host of Ca. L. asiaticus an...

  9. Use of the entomopathogenic fungi Metarhizium anisopliae, Cordyceps bassiana and Isaria fumosorosea to control Diaphorina citri (Hemiptera: Psylidae) in Persian lime under field conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is a destructive insect pest in the citriculture, because it is an efficient vector of the proteobacteria, ‘Candidatus Liberibacter asiaticus’ (Las), ‘Ca. L. Africanus’ (Laf), and ‘Ca. L. Americanus’ (Lam). These bacteria c...

  10. Evaluation of color and scent attractants used to trap and detect Asian ctirus psyllid (Diaphorina citri; Hemiptera:psyllidae)in urban environments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is a serious pest of citrus due to its ability to vector the putative causal agent of huanglongbing. Populations of Asian citrus psyllid (ACP) can increase in density in urban areas and then move out into adjacent commercial ...

  11. Ultrastructure of the salivary glands and bacteria-like structures in the gut and other organs of the Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae), vector of huanglongbing disease bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP, Diaphorina citri, Hemiptera, Liviidae) is the principal vector of Candidatus Liberibacter asiaticus (Las), the bacterium associated with huanglongbing (HLB) or citrus greening, currently the most serious citrus disease worldwide. Liberibacter asiaticus is transmitted i...

  12. Innate and Conditioned Responses to Chemosensory and Visual Cues in Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae), Vector of Huanglongbing Pathogens

    PubMed Central

    Patt, Joseph M.; Stockton, Dara; Meikle, William G.; Sétamou, Mamoudou; Mafra-Neto, Agenor; Adamczyk, John J.

    2014-01-01

    Asian citrus psyllid (Diaphorina citri) transmits Huanglongbing, a devastating disease that threatens citrus trees worldwide. A better understanding of the psyllid’s host-plant selection process may lead to the development of more efficient means of monitoring it and predicting its movements. Since behavioral adaptations, such as associative learning, may facilitate recognition of suitable host-plants, we examined whether adult D. citri could be conditioned to visual and chemosensory stimuli from host and non-host-plant sources. Response was measured as the frequency of salivary sheaths, the residue of psyllid probing activity, in a line of emulsified wax on the surface of a test arena. The psyllids displayed both appetitive and aversive conditioning to two different chemosensory stimuli. They could also be conditioned to recognize a blue-colored probing substrate and their response to neutral visual cues was enhanced by chemosensory stimuli. Conditioned psyllids were sensitive to the proportion of chemosensory components present in binary mixtures. Naïve psyllids displayed strong to moderate innate biases to several of the test compounds. While innate responses are probably the psyllid’s primary behavioral mechanism for selecting host-plants, conditioning may enhance its ability to select host-plants during seasonal transitions and dispersal. PMID:26462949

  13. Cloning and expressing a highly functional and substrate specific farnesoic acid o-methyltransferase from the Asian citrus psyllid (Diaphorina citri Kuwayama)

    PubMed Central

    Van Ekert, Evelien; Shatters, Robert G.; Rougé, Pierre; Powell, Charles A.; Smagghe, Guy; Borovsky, Dov

    2015-01-01

    The Asian citrus psyllid, Diaphorina citri, transmits a phloem-limited bacterium, Candidatus ‘Liberibacter’ asiaticus that causes citrus greening disease. Because juvenile hormone (JH) plays an important role in adult and nymphal development, we studied the final steps in JH biosynthesis in D. citri. A putative JH acid methyltransferase ortholog gene (jmtD) and its cognate cDNA were identified by searching D. citri genome database. Expression analysis shows expression in all life stages. In adults, it is expressed in the head-thorax, (containing the corpora allata), and the abdomen (containing ovaries and male accessory glands). A 3D protein model identified the catalytic groove with catalytically active amino acids and the S-adenosyl methionine (SAM)-binding loop. The cDNA was expressed in Escherichia coli cells and the purified enzyme showed high preference for farnesoic acid (FA) and homoFA (kcat of 0.752 × 10−3 and 0.217 × 10−3 s−1, respectively) as compared to JH acid I (JHA I) (cis/trans/cis; 2Z, 6E, 10cis), JHA III (2E, 6E, 10cis), and JHA I (trans/cis/cis; 2E, 2Z, 10cis) (kcat of 0.081 × 10−3, 0.013 × 10−3, and 0.003 × 10−3 s−1, respectively). This suggests that this ortholog is a DcFA-o-methyl transferase gene (fmtD), not a jmtD, and that JH biosynthesis in D. citri proceeds from FA to JH III through methyl farnesoate (MF). DcFA-o-MT does not require Ca2+, Mg2+ or Zn2+, however, Zn2+ (1 mM) completely inhibits the enzyme probably by binding H115 at the active groove. This represents the first purified FA-o-MT from Hemiptera with preferred biological activity for FA and not JHA. PMID:25893162

  14. Morphological abnormalities and cell death in the Asian citrus psyllid (Diaphorina citri) midgut associated with Candidatus Liberibacter asiaticus

    PubMed Central

    Ghanim, Murad; Fattah-Hosseini, Somayeh; Levy, Amit; Cilia, Michelle

    2016-01-01

    Candidatus Liberibacter asiaticus (CLas) is a phloem-limited, gram-negative, fastidious bacterium that is associated with the development of citrus greening disease, also known as Huanglongbing (HLB). CLas is transmitted by the Asian citrus psyllid (ACP) Diaphorina citri, in a circulative manner. Two major barriers to transmission within the insect are the midgut and the salivary glands. We performed a thorough microscopic analysis within the insect midgut following exposure to CLas-infected citrus trees. We observed changes in nuclear architecture, including pyknosis and karyorrhexis as well as changes to the actin cytoskeleton in CLas-exposed midgut cells. Further analyses showed that the changes are likely due to the activation of programmed cell death as assessed by Annexin V staining and DNA fragmentation assays. These results suggest that exposure to CLas-infected trees induces apoptotic responses in the psyllid midgut that should be further investigated. Understanding the adaptive significance of the apoptotic response has the potential to create new approaches for controlling HLB. PMID:27630042

  15. Diaphorina citri Induces Huanglongbing-Infected Citrus Plant Volatiles to Repel and Reduce the Performance of Propylaea japonica

    PubMed Central

    Lin, Yongwen; Lin, Sheng; Akutse, Komivi S.; Hussain, Mubasher; Wang, Liande

    2016-01-01

    Transmission of plant pathogens through insect vectors is a complex biological process involving interactions between the host plants, insects, and pathogens. Simultaneous impact of the insect damage and pathogenic bacteria in infected host plants induce volatiles that modify not only the behavior of its insect vector but also of their natural enemies, such as parasitoid wasps. Therefore, it is essential to understand how insects such as the predator ladybird beetle responds to volatiles emitted from a host plant and how the disease transmission alters the interactions between predators, vector, pathogens, and plants. In this study, we investigated the response of Propylaea japonica to volatiles from citrus plants damaged by Diaphorina citri and Candidatus Liberibacter asiaticus through olfactometer bioassays. Synthetic chemical blends were also used to determine the active compounds in the plant volatile. The results showed that volatiles emitted by healthy plants attracted more P. japonica than other treatments, due to the presence of high quantities of D-limonene and beta-ocimene, and the lack of methyl salicylate. When using synthetic chemicals in the olfactory tests, we found that D-limonene attracted P. japonica while methyl salicylate repelled the predator. However, beta-ocimene attracted the insects at lower concentrations but repelled them at higher concentrations. These results indicate that P. japonica could not efficiently search for its host by using volatile cues emitted from psyllids- and Las bacteria-infected citrus plants. PMID:28083006

  16. Host Range Testing of Diaphorencyrtus aligarhensis (Hymenoptera: Encyrtidae) for Use in Classical Biological Control of Diaphorina citri (Hemiptera: Liviidae) in California.

    PubMed

    Bistline-East, Allison; Pandey, Raju; Kececi, Mehmet; Hoddle, Mark S

    2015-06-01

    Host range tests for Diaphorencyrtus aligarhensis (Shafee, Alam, & Agarwal) (Hymenoptera: Encyrtidae), an endoparasitoid of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), sourced from Punjab Pakistan, were conducted in quarantine at the University of California, Riverside, CA. Seven nontarget psyllid species representing four psyllid families were exposed to mated D. aligarhensis females in four different treatment types: 1) short sequential no-choice treatments, 2) prolonged sequential no-choice treatments, 3) prolonged no-choice static treatments, and 4) choice treatments. Selection of nontarget psyllid species was based on phylogenetic proximity to D. citri, likelihood of being encountered by D. aligarhensis in the prospective release areas in California, and psyllid species in biological control of invasive weeds. D. aligarhensis exhibited high host affinity to D. citri, and only parasitized one nontarget species, the pestiferous potato psyllid, Bactericera cockerelli (Sulc), at low levels (<14%). Based on the results of this study, we conclude that D. aligarhensis has a narrow host range and exhibits a high level of host specificity, as it shows a significant attack preference for the target pest, D. citri. Results presented here suggest D. aligarhensis poses minimal risk to nontarget psyllid species in California.

  17. Risk assessment of various insecticides used for management of Asian citrus psyllid, Diaphorina citri in Florida citrus, against honey bee, Apis mellifera.

    PubMed

    Chen, Xue Dong; Gill, Torrence A; Pelz-Stelinski, Kirsten S; Stelinski, Lukasz L

    2017-01-23

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major pest of citrus trees worldwide. A wide variety of insecticides are used to manage D. citri populations within citrus groves in Florida. However, in areas shared by citrus growers and beekeepers the use of insecticides may increase the risks of Apis mellifera  L. (Hymenoptera: Apidae) loss and contaminated honey. The objective of this research was to determine the environmental toxicity of insecticides, spanning five different modes of action used to control D. citri, to A. mellifera. The insecticides investigated were imidacloprid, fenpropathrin, dimethoate, spinetoram and diflubenzuron. In laboratory experiments, LD50 values were determined and ranged from 0.10 to 0.53 ng/μl for imidacloprid, fenpropathrin, dimethoate and spinetoram. LD50 values for diflubenzuron were >1000 ng/μl. Also, a hazard quotient was determined and ranged from 1130.43 to 10893.27 for imidacloprid, fenpropathrin, dimethoate, and spinetoram. This quotient was <0.447 for diflubenzuron. In field experiments, residual activity of fenpropathrin and dimethoate applied to citrus caused significant mortality of A. mellifera 3 and 7 days after application. Spinetoram and imidacloprid were moderately toxic to A. mellifera at the recommended rates for D. citri. Diflubenzuron was not toxic to A. mellifera in the field as compared with untreated control plots. Phenoloxidase (PO) activity of A. mellifera was higher than in untreated controls when A. mellifera were exposed to 14 days old residues. The results indicate that diflubenzuron may be safe to apply in citrus when A. mellifera are foraging, while most insecticides used for management of D. citri in citrus are likely hazardous under various exposure scenarios.

  18. Roles of olfactory cues, visual cues, and mating status in orientation of Diaphorina citri Kuwayama (Hemiptera: Psyllidae) to four different host plants.

    PubMed

    Wenninger, Erik J; Stelinski, Lukasz L; Hall, David G

    2009-02-01

    Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is an important worldwide pest of citrus that vectors bacteria (Candidatus Liberibacter spp.) responsible for huanglongbing (citrus greening disease). We examined the behavioral responses of mated and unmated D. citri of both sexes to odors from host plants in a Y-tube olfactometer, with and without visual cues. The host plants tested were 'Duncan' grapefruit (Citrus paradisi Macfayden), sour orange (Citrus aurantium L.), navel orange (C. sinensis L.), and Murraya paniculata L. Jack. Responses varied by plant species, psyllid sex and mating status, and the presence of a visual cue. Evidence of attraction generally was stronger in females and in mated individuals of both sexes relative to virgins. The presence of a visual cue typically enhanced attractiveness of olfactory cues; in no case did unmated individuals show evidence of attraction to host plant odors in the absence of avisual cue. In the absence of visual cues, mated females and males showed evidence of attraction only to odors from sour orange and navel orange, respectively. Psyllids exhibited anemotactic responses when assayed with plant odors alone but showed strong evidence of attraction only when olfactory and visual cues were combined, suggesting that olfactory cues facilitate orientation to host plants but may be insufficient alone. Antennal responses to citrus volatiles were confirmed by electroantennogram. The results reported here provide evidence that D. citri uses olfactory and visual cues in orientation to host plants and suggest the possibility of using plant volatiles in monitoring and management of this pest.

  19. Impacts of Horticultural Mineral Oils and Two Insecticide Practices on Population Fluctuation of Diaphorina citri and Spread of Huanglongbing in a Citrus Orchard in Sarawak

    PubMed Central

    Leong, Stephen Chan Teck; Abang, Fatimah; Beattie, Andrew; Kueh, Roland Jui Heng; Wong, Sing King

    2012-01-01

    Aspects of the incidence and spread of the citrus disease huanglongbing (HLB) in relation to the vector Diaphorina citri population fluctuation were studied from January 1999 to December 2001 seasons in a 0.8 ha citrus orchard at Jemukan (1° 33′N, 110° 41′E), Southwest Sarawak in Malaysia. In relation to insecticide and horticultural mineral oils (HMOs) use, levels of HLB infection rose quite rapidly over the next 3 years in the unsprayed control and less rapidly in the other treatments such as imidacloprid, nC24HMO, and triazophos/cypermethrin/chlorpyrifos. Levels of HLB as determined by Polymerase Chain Reaction (PCR) were 42.2%, 9.4%, 11.4%, and 22.7%, respectively. The effects of nC24HMO and conventional pesticides on the citrus psyllid population and parasitoids in citrus orchard were also determined. PMID:22629178

  20. Synchronized rearing of mated and unmated Diaphorina Citri (Hemiptera:liviidae) of known age

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methods were developed for synchronized rearing of unmated and mated ACP of known age in isolation chambers for behavioral studies. Maintenance and survival of nymphs and adults in the isolation chambers was improved over previous methods because the plants had more room to grow and the relative hum...

  1. Overview of worldwide diversity of Diaphorina citri Kuwayama mitochondrial cytochrome oxidase 1 haplotypes: two Old World lineages and a New World invasion

    PubMed Central

    Boykin, L.M.; De Barro, P.; Hall, D.G.; Hunter, W.B.; McKenzie, C.L.; Powell, C.A.; Shatters, R.G.

    2012-01-01

    Relationships among worldwide collections of Diaphorina citri (Asian citrus psyllid) were analyzed using mitochondrial cytochrome oxidase I (mtCOI) haplotypes from novel primers. Sequences were produced from PCR amplicons of an 821bp portion of the mtCOI gene using D. citri specific primers, derived from an existing EST library. An alignment was constructed using 612bps of this fragment and consisted of 212 individuals from 52 collections representing 15 countries. There were a total of eight polymorphic sites that separated the sequences into eight different haplotypes (Dcit-1 through Dcit-8). Phylogenetic network analysis using the statistical parsimony software, TCS, suggests two major haplotype groups with preliminary geographic bias between southwestern Asia (SWA) and southeastern Asia (SEA). The recent (within the last 15 to 25 years) invasion into the New World originated from only the SWA group in the northern hemisphere (USA and Mexico) and from both the SEA and SWA groups in the southern hemisphere (Brazil). In only one case, Reunion Island, did haplotypes from both the SEA and SWA group appear in the same location. In Brazil, both groups were present, but in separate locations. The Dcit-1 SWA haplotype was the most frequently encountered, including ~50% of the countries sampled and 87% of the total sequences obtained from India, Pakistan and Saudi Arabia. The second most frequently encountered haplotype, Dcit-2, the basis of the SEA group, represented ~50% of the countries and contained most of the sequences from Southeast Asia and China. Interestingly, only the Caribbean collections (Puerto Rico and Guadeloupe) represented a unique haplotype not found in other countries, indicating no relationship between the USA (Florida) and Caribbean introductions. There is no evidence for cryptic speciation for D. citri based on the COI region included in this study. PMID:22717059

  2. Nested-quantitative PCR approach with improved sensitivity for the detection of low titer levels of Candidatus Liberibacter asiaticus in the Asian citrus psyllid, Diaphorina citri Kuwayama.

    PubMed

    Coy, M R; Hoffmann, M; Kingdom Gibbard, H N; Kuhns, E H; Pelz-Stelinski, K S; Stelinski, L L

    2014-07-01

    Candidatus Liberibacter asiaticus (CLas) is a phloem-limited bacterium transmitted by the Asian citrus psyllid, Diaphorina citri, and the presumptive causal agent of citrus greening disease. The current method of detection for CLas within plant and insect samples is by a presence/absence qPCR assay using the CLas 16S rDNA gene target. Although qPCR is highly sensitive, low bacterial titers or suboptimal qPCR conditions can result in false-negatives. Using a nested qPCR assay, we determined the false-negative rate of the 16S presence/absence qPCR assay was greater than 50%. Studies to determine the performance parameters of the qPCR assays for CLas 16S and Wingless (Wg), the D. citri endogenous gene, using plasmid and psyllid DNA, revealed suboptimal and variable performance of the 16S assay in psyllid samples. Average efficiencies and sensitivity limits of the plasmid assays were 99.0% and 2.7 copies of template for Wg, respectively, and 98.5% and 2.2-22.1 copies for 16S, respectively. Variability in efficiency was significantly greater in psyllid samples for both gene targets compared to the corresponding plasmid assays, and efficiencies as low as 76% were obtained for 16S. A secondary structure analysis revealed the formation of two stem-loop structures that block the forward and probe binding sites in the 16S template, which could hinder amplification. In summary, our results suggest that suboptimal qPCR efficiency is not uncommon for the 16S presence/absence qPCR assay, which combined with lowCLas titers in some samples, could contribute significantly to the under-reporting of CLas infection in psyllid and plant samples.

  3. Essential Oil Variation from Twenty Two Genotypes of Citrus in Brazil-Chemometric Approach and Repellency Against Diaphorina citri Kuwayama.

    PubMed

    Andrade, Moacir Dos Santos; Ribeiro, Leandro do Prado; Borgoni, Paulo Cesar; Silva, Maria Fátima das Graças Fernandes da; Forim, Moacir Rossi; Fernandes, João Batista; Vieira, Paulo Cezar; Vendramin, José Djair; Machado, Marcos Antônio

    2016-06-22

    The chemical composition of volatile oils from 22 genotypes of Citrus and related genera was poorly differentiated, but chemometric techniques have clarified the relationships between the 22 genotypes, and allowed us to understand their resistance to D. citri. The most convincing similarities include the synthesis of (Z)-β-ocimene and (E)-caryophyllene for all 11 genotypes of group A. Genotypes of group B are not uniformly characterized by essential oil compounds. When stimulated with odor sources of 22 genotypes in a Y-tube olfactometer D. citri preferentially entered the arm containing the volatile oils of Murraya paniculata, confirming orange jasmine as its best host. C. reticulata × C. sinensis was the least preferred genotype, and is characterized by the presence of phytol, (Z)-β-ocimene, and β-elemene, which were not found in the most preferred genotype. We speculate that these three compounds may act as a repellent, making these oils less attractive to D. citri.

  4. Detection of citrus huanglongbing-associated 'Candidatus Liberibacter asiaticus' in citrus and Diaphorina citri in Pakistan, seasonal variability, and implications for disease management.

    PubMed

    Razi, Muhammad F; Keremane, Manjunath L; Ramadugu, Chandrika; Roose, Mikeal; Khan, Iqrar A; Lee, Richard F

    2014-03-01

    We report the detection of the huanglongbing (HLB)-associated bacterium 'Candidatus Liberibacter asiaticus' from both plants and insects in Pakistan and the seasonal variability in the numbers of 'Ca. L. asiaticus'-positive psyllid vector, Diaphorina citri. Our studies showed that 'Ca. L. asiaticus' was detectable from trees in areas with maximum temperatures reaching nearly 50°C (average maximum of 42°C). However, the bacterium was present at very low levels in psyllids both in summer (June to August) and autumn (September to November) in contrast to reports from Florida, where the bacterium was detectable at very high levels during October to November. We hypothesize that hot summer temperatures in Pakistan may interfere with acquisition and replication of 'Ca. L. asiaticus' in psyllids and may lead to dead or non transmissible 'Ca. L. asiaticus' in plants. Psyllid counts were very low in both summer and winter, showed a population peak ('Ca. L. asiaticus'-positive vectors) in spring, and showed a larger peak ('Ca. L. asiaticus'-free psyllids) in autumn. Natural thermotherapy during hot summers and a low vector population during environmental extremes may have played a major role in long-term survival of the citrus industry in Pakistan. These results may be useful in developing management strategies for U.S. citrus industries in Texas and California.

  5. Daily and seasonal patterns in abdomen color in Diaphoria citri (Hemiptera: Psyllidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diaphorina citri Kuwayama, a psyllid vector of huanglongbing (citrus greening disease), exhibits three more or less distinct abdomen colors in the adult psyllid: gray/brown, blue/green, and orange/yellow. We explored the daily (in individuals in the laboratory) and seasonal (in a field population) p...

  6. Infection Density Dynamics of the Citrus Greening Bacterium “Candidatus Liberibacter asiaticus” in Field Populations of the Psyllid Diaphorina citri and Its Relevance to the Efficiency of Pathogen Transmission to Citrus Plants

    PubMed Central

    Ukuda-Hosokawa, Rie; Sadoyama, Yasutsune; Kishaba, Misaki; Kuriwada, Takashi; Anbutsu, Hisashi

    2015-01-01

    Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, “Candidatus Liberibacter asiaticus,” and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of “Ca. Liberibacter asiaticus” in field populations of D. citri with experiments using field-collected insects to address how “Ca. Liberibacter asiaticus” infection density in the vector insect is relevant to pathogen transmission to citrus plants. Of 500 insects continuously collected from “Ca. Liberibacter asiaticus”-infected citrus trees with pathological symptoms in the spring and autumn of 2009, 497 (99.4%) were “Ca. Liberibacter asiaticus” positive. The infections were systemic across head-thorax and abdomen, ranging from 103 to 107 bacteria per insect. In spring, the infection densities were low in March, at ∼103 bacteria per insect, increasing up to 106 to 107 bacteria per insect in April and May, and decreasing to 105 to 106 bacteria per insect in late May, whereas the infection densities were constantly ∼106 to 107 bacteria per insect in autumn. Statistical analysis suggested that several factors, such as insect sex, host trees, and collection dates, may be correlated with “Ca. Liberibacter asiaticus” infection densities in field D. citri populations. Inoculation experiments with citrus seedlings using field-collected “Ca. Liberibacter asiaticus”-infected insects suggested that (i) “Ca. Liberibacter asiaticus”-transmitting insects tend to exhibit higher infection densities than do nontransmitting insects, (ii) a threshold level (∼106 bacteria per insect) of “Ca. Liberibacter asiaticus” density in D. citri is required for successful transmission to citrus plants, and (iii) D. citri attaining the threshold infection level transmits “Ca. Liberibacter asiaticus” to citrus plants in a stochastic manner. These

  7. Infection Density Dynamics of the Citrus Greening Bacterium "Candidatus Liberibacter asiaticus" in Field Populations of the Psyllid Diaphorina citri and Its Relevance to the Efficiency of Pathogen Transmission to Citrus Plants.

    PubMed

    Ukuda-Hosokawa, Rie; Sadoyama, Yasutsune; Kishaba, Misaki; Kuriwada, Takashi; Anbutsu, Hisashi; Fukatsu, Takema

    2015-06-01

    Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, "Candidatus Liberibacter asiaticus," and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of "Ca. Liberibacter asiaticus" in field populations of D. citri with experiments using field-collected insects to address how "Ca. Liberibacter asiaticus" infection density in the vector insect is relevant to pathogen transmission to citrus plants. Of 500 insects continuously collected from "Ca. Liberibacter asiaticus"-infected citrus trees with pathological symptoms in the spring and autumn of 2009, 497 (99.4%) were "Ca. Liberibacter asiaticus" positive. The infections were systemic across head-thorax and abdomen, ranging from 10(3) to 10(7) bacteria per insect. In spring, the infection densities were low in March, at ∼ 10(3) bacteria per insect, increasing up to 10(6) to 10(7) bacteria per insect in April and May, and decreasing to 10(5) to 10(6) bacteria per insect in late May, whereas the infection densities were constantly ∼ 10(6) to 10(7) bacteria per insect in autumn. Statistical analysis suggested that several factors, such as insect sex, host trees, and collection dates, may be correlated with "Ca. Liberibacter asiaticus" infection densities in field D. citri populations. Inoculation experiments with citrus seedlings using field-collected "Ca. Liberibacter asiaticus"-infected insects suggested that (i) "Ca. Liberibacter asiaticus"-transmitting insects tend to exhibit higher infection densities than do nontransmitting insects, (ii) a threshold level (∼ 10(6) bacteria per insect) of "Ca. Liberibacter asiaticus" density in D. citri is required for successful transmission to citrus plants, and (iii) D. citri attaining the threshold infection level transmits "Ca. Liberibacter asiaticus" to citrus plants in a stochastic manner. These findings provide

  8. Oviposition behavior and survival of Tamarixia radiata (Hymenoptera: Eulophidae), an ectoparasitoid of the Asian citrus psyllid, Diaphorina citri, on hosts exposed to the entomopathogenic fungus, Isaria fumosorosea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antagonistic interactions between the nymphal parasitoid, Tamarixia radiata Waterston (Hymenoptera: Eulophidae), and the ARSEF 3581 isolate of the entomopathogenic fungus, Isaria fumosorosea Wize (Hypocreales: Cordycipitaceae) could disrupt biological control of the Asian citrus psyllid, Diaphorina ...

  9. Retracted stylets in nymphs of the Asian citrus psyllid are held externally against the clypeus by a special paired organ not found in the adults

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Differences in ultrastructure of the mouthparts in nymphs and adults of the Asian citrus psyllid Diaphorina citri (Hemiptera, Psyllidae), vector of the bacterium associated with citrus huanglongbing disease, were studied using scanning electron microscopy. The number of sensilla on the labial tip in...

  10. Compatibility of Isaria fumosorosea (Hypocreales: Cordycipitaceae) Blastospores with Agricultural Chemicals Used for Management of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae)

    PubMed Central

    Avery, Pasco B.; Pick, David A.; Aristizábal, Luis F.; Kerrigan, James; Powell, Charles A.; Rogers, Michael E.; Arthurs, Steven P.

    2013-01-01

    Biorational insecticides are being increasingly emphasized for inclusion in integrated pest management programs for invasive insects. The entomopathogenic fungus, Isaria fumosorosea, can be used to help manage the Asian citrus psyllid with minimal impact on beneficial arthropods, but its effectiveness may be compromised by agrochemicals used to control concurrent arthropod pests and diseases. We evaluated the compatibility of I. fumosorosea blastospores with a range of spray oils and copper-based fungicides registered for use in citrus groves. Results of laboratory and greenhouse tests showed a range of responses of the fungus to the different materials, including compatibility and incompatibility. Overall, I. fumosorosea growth in vitro was reduced least by petroleum-based materials and most by botanical oils and borax, and some of the copper-based fungicides, suggesting that tank mixing of I. fumosorosea with these latter products should be avoided. However, equivalent negative effects of test materials on fungal pathogenicity were not always observed in tests with adult psyllids. We hypothesize that some oils enhanced adherence of blastospores to the insect cuticle, overcoming negative impacts on germination. Our data show that care should be taken in selecting appropriate agrochemicals for tank-mixing with commercial formulations of entomopathogenic fungi for management of citrus pests. The prospects of using I. fumosorosea for managing the invasive Asian citrus psyllid and other citrus pests are discussed. PMID:26462531

  11. Host plant affects morphometric variation of Diaphorina citri (Hemiptera: Liviidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP), due to its potential to vector the pathogen causing citrus greening disease or huanglongbing, is one of the most serious citrus pests worldwide. While optimal plant cultivars for ACP oviposition and development have been determined, little is known of the influence of...

  12. The behavioral response of Diaphorina citri to ultraviolet light

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP) is responsible for transmitting greening or huanglongbing (HLB) to citrus. It is considered the most debilitating disease of citrus worldwide. Currently, citrus growers rely on insecticides to control ACP. Previous studies, employing metalized mulch have successfully r...

  13. Attraction of Diaphorina citri (Hemiptera: Liviidae) to colored light

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The most devasting disease of citrus, huanglongbing (HLB), is spread by the insect vector the Asian Citrus Psyllid (ACP). Although ACP are known to respond to visual cues, previous studies have not documented the specific wavelengths of light attractive to ACP. The objectives of this study were to...

  14. Antibacterial Activity of Alkyl Gallates against Xanthomonas citri subsp. citri

    PubMed Central

    Silva, I. C.; Regasini, L. O.; Petrônio, M. S.; Silva, D. H. S.; Bolzani, V. S.; Belasque, J.; Sacramento, L. V. S.

    2013-01-01

    The plant-pathogenic bacterium Xanthomonas citri subsp. citri is the causal agent of Asiatic citrus canker, a serious disease that affects all the cultivars of citrus in subtropical citrus-producing areas worldwide. There is no curative treatment for citrus canker; thus, the eradication of infected plants constitutes the only effective control of the spread of X. citri subsp. citri. Since the eradication program in the state of São Paulo, Brazil, is under threat, there is a clear risk of X. citri subsp. citri becoming endemic in the main orange-producing area in the world. Here we evaluated the potential use of alkyl gallates to prevent X. citri subsp. citri growth. These esters displayed a potent anti-X. citri subsp. citri activity similar to that of kanamycin (positive control), as evaluated by the resazurin microtiter assay (REMA). The treatment of X. citri subsp. citri cells with these compounds induced altered cell morphology, and investigations of the possible intracellular targets using X. citri subsp. citri strains labeled for the septum and centromere pointed to a common target involved in chromosome segregation and cell division. Finally, the artificial inoculation of citrus with X. citri subsp. citri cells pretreated with alkyl gallates showed that the bacterium loses the ability to colonize its host, which indicates the potential of these esters to protect citrus plants against X. citri subsp. citri infection. PMID:23104804

  15. Acquisition, replication and inoculation of Candidatus Liberibacter asiaticus following various acquisition periods on Huanglongbing-infected citrus by nymphs and adults of the Asian citrus psyllid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), is the primary vector of Candidatus Liberibacter asiaticus (Las) implicated as causative agent of citrus huanglongbing (citrus greening), currently the most serious citrus disease worldwide. Las is transmitted by D. citri in a persist...

  16. Acquisition, Replication and Inoculation of Candidatus Liberibacter asiaticus following Various Acquisition Periods on Huanglongbing-Infected Citrus by Nymphs and Adults of the Asian Citrus Psyllid

    PubMed Central

    Ammar, El-Desouky; Ramos, John E.; Hall, David G.; Dawson, William O.; Shatters, Robert G.

    2016-01-01

    The Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), is the primary vector of Candidatus Liberibacter asiaticus (Las) implicated as causative agent of citrus huanglongbing (citrus greening), currently the most serious citrus disease worldwide. Las is transmitted by D. citri in a persistent-circulative manner, but the question of replication of this bacterium in its psyllid vector has not been resolved. Thus, we studied the effects of the acquisition access period (AAP) by nymphs and adults of D. citri on Las acquisition, multiplication and inoculation/transmission. D. citri nymphs or adults (previously non-exposed to Las) were caged on Las-infected citrus plants for an AAP of 1, 7 or 14 days. These ‘Las-exposed’ psyllids were then transferred weekly to healthy citrus or orange jasmine plants, and sampled via quantitative polymerase chain reaction (qPCR) analysis 1–42 days post-first access to diseased plants (padp); all tested nymphs became adults 7–14 days padp. Our results indicate that following 1 or 7 day AAP as nymphs 49–59% of Las-exposed psyllids became Las-infected (qPCR-positive), whereas only 8–29% of the psyllids were infected following 1–14 day AAP as adults. Q-PCR analysis also indicated that Las titer in the Las-exposed psyllids (relative to that of the psyllid S20 ribosomal protein gene) was: 1) significantly higher, and increasing at a faster rate, following Las acquisition as nymphs compared to that following Las acquisition as adults; 2) higher as post-acquisition time of psyllids on healthy plants increased reaching a peak at 14–28 days padp for nymphs and 21–35 days padp for adults, with Las titer decreasing or fluctuating after that; 3) higher with longer AAP on infected plants, especially with acquisition as adults. Our results strongly suggest that Las multiplies in both nymphs and adults of D. citri but attains much higher levels in a shorter period of time post-acquisition when acquired by nymphs than when

  17. Ontogenic variation in citrus flush shoots and its relation with host plant finding and acceptance by Asian citrus psyllid (Hemiptera: Psyllidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae) is a destructive insect mainly because it vectors the bacterial pathogens that cause the deadly and incurable citrus greening disease. Diaphorina citri adult females lay eggs and immature development occurs exclusively on new flush sh...

  18. Probing behaviors of adult Asian citrus psyllid (Hemiptera: Psyllidae)are not appreciably affected by soil application of field-rate aldicarb to citrus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2005, Huanglongbing disease (HLB), also known as citrus greening, was discovered in Florida. The presumptive causal agent of this disease is the phloem-limited bacterium Candidatus Liberibacter asiaticus (Las), which is transmitted by the Asian citrus psyllid,Diaphorina citri Kuwayama. Following ...

  19. Visual behavior of the Asian Citrus Psyllid Diaphorina citri (Hemiptera: Liviidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As the vector of the global disease of citrus greening or huanglongbing (HLB), relatively little is known concerning the Asian Citrus Psyllid (ACP) behavior towards visual cues. The objective of this study was to elucidate behavioral responses of ACP towards several colors of light. ACP responded ...

  20. A comparison of sticky traps for monitoring Asian citrus psyllid (Diaphorina citri Kuwayama)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Six types of sticky card traps differing in color and trapping adhesive were evaluated for monitoring Asian citrus psyllid in citrus in the United States (Florida and Texas). Spectral reflectance measurements were taken to categorize the color (wavelength) spectrum of each trap. Three of the traps (...

  1. Whole genome sequence of “Candidatus Profftella armatura” from Diaphorina citri in Guangdong, China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genome of “Candidatus Profftella armatura” strain YCPA, a symbiont of Asian citrus psyllid, from Guangdong, China, was sequenced. The strain chromosome was 457,565 bp with 24.3% G+C content, 364 predicted open reading frames (ORFs), and 38 RNA genes. The strain also contains a 5,458 bp plasmid, ...

  2. Screening Citrus germplasm for tolerance to HLB and Diaphorina citri--progress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This article summarizes a project that is being funded in part by the California Citrus Research Board. In a previous field trial, 87 genotypes of citrus were planted in the field in Florida and the different genotypes were evaluated for tolerance to Asian citrus psyllid, citrus leaf miner, and hua...

  3. Local genetic diversity of Xanthomonas citri subsp. citri in citrus orchards in northwest Paraná state, Brazil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xanthomonas citri subsp. citri, causal agent of Asiatic citrus canker, is an important pathogen of citrus in Brazil and elsewhere. The genetic diversity of X. citri subsp. citri pathtype ‘A’ has not been studied in Brazil at a local scale (up to 300 km). A total of 40 isolates were collected from le...

  4. Asymmetric chromosome segregation in Xanthomonas citri ssp. citri

    PubMed Central

    Ucci, Amanda P; Martins, Paula M M; Lau, Ivy F; Bacci, Maurício; Belasque, José; Ferreira, Henrique

    2014-01-01

    This study was intended to characterize the chromosome segregation process of Xanthomonas citri ssp. citri (Xac) by investigating the functionality of the ParB factor encoded on its chromosome, and its requirement for cell viability and virulence. Using TAP tagging we show that ParB is expressed in Xac. Disruption of parB increased the cell doubling time and precluded the ability of Xac to colonize the host citrus. Moreover, Xac mutant cells expressing only truncated forms of ParB exhibited the classical phenotype of aberrant chromosome organization, and seemed affected in cell division judged by their reduced growth rate and the propensity to form filaments. The ParB-GFP localization pattern in Xac was suggestive of an asymmetric mode of replicon partitioning, which together with the filamentation phenotype support the idea that Xac may control septum placement using mechanisms probably analogous to Caulobacter crescentus, and perhaps Vibrio cholerae, and Corynebacterium glutamicum. Xac exhibits asymmetric chromosome segregation, and the perturbation of this process leads to an inability to colonize the host plant. PMID:24339434

  5. Toxicity of pesticides to Tamarixia radiata, a parasitoid of the Asian citrus psyllid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sixteen pesticides including two fungicides were evaluated for toxicity to adult Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae), a parasitoid of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Percentage mortality data were evaluated to generally assess IPM-com...

  6. Predisposition of citrus foliage to infection with Xanthomonas citri subsp. citri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus canker (caused by Xanthomonas citri subsp. citri, Xcc) is a serious disease of susceptible citrus in Florida and other citrus-growing areas of the world. The effect of leaf preconditioning as a route for entry of the bacteria is poorly characterized. A series of experiments were designed to i...

  7. Resistance of sweet orange Pera (Citrus sinensis) genotypes to Xanthomonas citri subsp. citri under field conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus canker control is based on protection measures and eradication of plants infected with Xanthomonas citri subsp. citri. Although these measures show satisfactory results, the use of resistant genotypes is an important alternative for citrus canker control. The aim of this study was to evaluate...

  8. Protein depletion using the arabinose promoter in Xanthomonas citri subsp. citri.

    PubMed

    Lacerda, Lilian A; Cavalca, Lucia B; Martins, Paula M M; Govone, José S; Bacci, Maurício; Ferreira, Henrique

    2017-03-23

    Xanthomonas citri subsp. citri (X. citri) is a plant pathogen and the etiological agent of citrus canker, a severe disease that affects all the commercially important citrus varieties, and has worldwide distribution. Citrus canker cannot be healed, and the best method known to control the spread of X. citri in the orchards is the eradication of symptomatic and asymptomatic plants in the field. However, in the state of São Paulo, Brazil, the main orange producing area in the world, control is evolving to an integrated management system (IMS) in which growers have to use less susceptible plants, windshields to prevent bacterial spread out and sprays of cupric bactericidal formulations. Our group has recently proposed alternative methods to control citrus canker, which are based on the use of chemical compounds able to disrupt vital cellular processes of X. citri. An important step in this approach is the genetic and biochemical characterization of genes/proteins that are the possible targets to be perturbed, a task not always simple when the gene/protein under investigation is essential for the organism. Here, we describe vectors carrying the arabinose promoter that enable controllable protein expression in X. citri. These vectors were used as complementation tools for the clean deletion of parB in X. citri, a widespread and conserved gene involved in the essential process of bacterial chromosome segregation. Overexpression or depletion of ParB led to increased cell size, which is probably a resultant of delayed chromosome segregation with subsequent retard of cell division. However, ParB is not essential in X. citri, and in its absence the bacterium was fully competent to colonize the host citrus and cause disease. The arabinose expression vectors described here are valuable tools for protein expression, and especially, to assist in the deletion of essential genes in X. citri.

  9. Potential of South African entomopathogenic nematodes (Heterorhabditidae and Steinernematidae) for control of the citrus mealybug, Planococcus citri (Pseudococcidae).

    PubMed

    van Niekerk, Sonnica; Malan, Antoinette P

    2012-10-01

    Planococcus citri, the citrus mealybug, is the most important species of mealybug known to infest citrus in South Africa. Various laboratory bioassays were conducted to determine the potential of entomopathogenic nematodes to control P. citri. Adult female P. citri were screened for susceptibility to six indigenous nematode species. P. citri was found to be most susceptible to Steinernema yirgalemense and Heterorhabditis zealandica, causing 97% and 91% mortality, respectively. The development of nematodes after infecting adult female P. citri showed both H. zealandica and S. yirgalemense were able to complete their life cycles inside the host. Further bioassays illustrated a linear relationship between mealybug mortality and the concentration of nematodes applied, with the highest level of control using a concentration of 80 infective juveniles (IJs)/insect. As nematodes would be used as an above-ground application to control P. citri in citrus orchards, available water is a major limiting factor. Insecticidal activity proved to be dependent on the available surface moisture after nematode application. The water activity (a(w)) bioassay indicated that S. yirgalemense to be two times more tolerant to lower levels of free water, with a(w50)=0.96 and a(w90)=0.99, compared to H. zealandica with a(w50)=0.98 and a(w)90=1.0. After application, nematodes have a limited time frame in which to locate and infect hosts, as the level of available free water gradually decreases, as trees dry out. S. yirgalemense proved able to locate and infect P. citri quicker than H. zealandica. Nematode activity was not significantly affected when exposed to 15°C, 20°C and 25°C. IJs were able to infect P. citri at an exposure time as short as half an hour. Results also showed that the first 2-4h post application is the most decisive time for establishing successful infection of mealybugs. This is the first report on the potential use of nematodes for the control of P. citri.

  10. Structural and functional characterization of the phosphoglucomutase from Xanthomonas citri subsp. citri.

    PubMed

    Goto, Leandro Seiji; Vessoni Alexandrino, André; Malvessi Pereira, Camila; Silva Martins, Carla; D'Muniz Pereira, Humberto; Brandão-Neto, José; Marques Novo-Mansur, Maria Teresa

    2016-12-01

    Citrus canker, caused by bacteria Xanthomonas citri subsp. citri, can affect all economically important varieties of citrus. Studying Xanthomonas genes related to the invasive capacity may improve the knowledge on how this works and ultimately use the information to avoid the disease. Some annotated genes from Xanthomonas citri subsp. citri published genome are addressed to an interesting class of genes named "pathogenicity, virulence and adaptation". One of them is xanA, which encodes a predicted phosphoglucomutase. Phosphoglucomutases are ubiquitous enzymes among the living kingdoms that play roles in carbohydrate metabolism, catalyzing the reversible conversion of 1- to 6-phosphoglucose. In Xanthomonas, phosphoglucomutase activity is required to synthesize precursors of the pathogenesis-related polysaccharide xanthan. In this work, a characterization of this gene product is presented by structural and functional studies. Molecular cloning was used for heterologous expression and deletion of xanA. A Michaelis-Menten kinetics model was obtained using the recombinant protein. The protein structure was also determined by X-ray diffraction on the recombinant enzyme substrate-free, bound to glucose-1,6-biphosphate and to glucose-1-phosphate. Deletion of xanA was done with a suicide plasmid construct and the obtained mutant was tested for pathogenic capacity. This study is the first describing the properties of the Xanthomonas citri subsp. citri phosphoglucomutase.

  11. The type III protein secretion system contributes to Xanthomonas citri subsp. citri biofilm formation

    PubMed Central

    2014-01-01

    Background Several bacterial plant pathogens colonize their hosts through the secretion of effector proteins by a Type III protein secretion system (T3SS). The role of T3SS in bacterial pathogenesis is well established but whether this system is involved in multicellular processes, such as bacterial biofilm formation has not been elucidated. Here, the phytopathogen Xanthomonas citri subsp. citri (X. citri) was used as a model to gain further insights about the role of the T3SS in biofilm formation. Results The capacity of biofilm formation of different X. citri T3SS mutants was compared to the wild type strain and it was observed that this secretion system was necessary for this process. Moreover, the T3SS mutants adhered proficiently to leaf surfaces but were impaired in leaf-associated growth. A proteomic study of biofilm cells showed that the lack of the T3SS causes changes in the expression of proteins involved in metabolic processes, energy generation, exopolysaccharide (EPS) production and bacterial motility as well as outer membrane proteins. Furthermore, EPS production and bacterial motility were also altered in the T3SS mutants. Conclusions Our results indicate a novel role for T3SS in X. citri in the modulation of biofilm formation. Since this process increases X. citri virulence, this study reveals new functions of T3SS in pathogenesis. PMID:24742141

  12. Identification of an Extracellular Endoglucanase That Is Required for Full Virulence in Xanthomonas citri subsp. citri

    PubMed Central

    Sun, Dongling; Zhuo, Tao; Fan, Xiaojing; Zou, Huasong

    2016-01-01

    Xanthomonas citri subsp. citri causes citrus canker disease, which is characterized by the formation of water-soaked lesions, white or yellow spongy pustules and brown corky canker. In this work, we report the contribution of extracellular endoglucanase to canker development during infection. The ectopic expression of nine putative cellulases in Escherichia coli indicated that two endoglucanases, BglC3 and EngXCA, show carboxymethyl cellulase activity. Both bglC3 and engXCA genes were transcribed in X. citri subsp. citri, however, only BglC3 protein was detected outside the cell in western blot analysis. The deletion of bglC3 gene resulted in complete loss of extracellular carboxymethyl cellulase activity and delayed the onset of canker symptoms in both infiltration- and wound-inoculation assays. When growing in plant tissue, the cell density of bglC3 mutant was lower than that of the wild type. Our data demonstrated that BglC3 is an extracellular endoglucanase required for the full virulence of X. citri subsp. citri. PMID:26950296

  13. Complete Genome Sequences of Six Copper-Resistant Xanthomonas citri pv. citri Strains Causing Asiatic Citrus Canker, Obtained Using Long-Read Technology

    PubMed Central

    Richard, Damien; Boyer, Claudine; Vernière, Christian; Canteros, Blanca I.; Lefeuvre, Pierre

    2017-01-01

    ABSTRACT The gammaproteobacterium Xanthomonas citri pv. citri causes Asiatic citrus canker. Pathotype A strains have a broad host range, which includes most commercial citrus species, and they cause important economic losses worldwide. Control often relies on frequent copper sprays. We present here the complete genomes of six X. citri pv. citri copper-resistant strains. PMID:28336584

  14. Comparison of Potato and Asian Citrus Psyllid Adult and Nymph Transcriptomes Identified Vector Transcripts with Potential Involvement in Circulative, Propagative Liberibacter Transmission

    PubMed Central

    Fisher, Tonja W.; Vyas, Meenal; He, Ruifeng; Nelson, William; Cicero, Joseph M.; Willer, Mark; Kim, Ryan; Kramer, Robin; May, Greg A.; Crow, John A.; Soderlund, Carol A.; Gang, David R.; Brown, Judith K.

    2014-01-01

    The potato psyllid (PoP) Bactericera cockerelli (Sulc) and Asian citrus psyllid (ACP) Diaphorina citri Kuwayama are the insect vectors of the fastidious plant pathogen, Candidatus Liberibacter solanacearum (CLso) and Ca. L. asiaticus (CLas), respectively. CLso causes Zebra chip disease of potato and vein-greening in solanaceous species, whereas, CLas causes citrus greening disease. The reliance on insecticides for vector management to reduce pathogen transmission has increased interest in alternative approaches, including RNA interference to abate expression of genes essential for psyllid-mediated Ca. Liberibacter transmission. To identify genes with significantly altered expression at different life stages and conditions of CLso/CLas infection, cDNA libraries were constructed for CLso-infected and -uninfected PoP adults and nymphal instars. Illumina sequencing produced 199,081,451 reads that were assembled into 82,224 unique transcripts. PoP and the analogous transcripts from ACP adult and nymphs reported elsewhere were annotated, organized into functional gene groups using the Gene Ontology classification system, and analyzed for differential in silico expression. Expression profiles revealed vector life stage differences and differential gene expression associated with Liberibacter infection of the psyllid host, including invasion, immune system modulation, nutrition, and development. PMID:25436509

  15. Asian citrus psyllids and shade: Survival of Diaphorina citri on Murraya exotica foliage exposed to different levels of light

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using shade cloths of different densities, potted individuals of Murraya exotica (Rutaceae) were exposed to levels of photosynthetic radiation (PAR) varying from 48 µmol photons per meter2 per second to 1562 µmol photons per meter2 per second (average of three readings taken at noon during condition...

  16. Studies of in aere formed stylet sheath from the Asian citrus psyllid (Diaphorina citri, Hemiptera: Psyllidae) and other phytophagous Hemiptera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stylet sheath formation is a common feature among phytophagous hemipterans. These sheaths are considered essential to promote a successful feeding event of these piercing-sucking insects. The stylet sheath composition is unknown and it is suggested that it forms through interactions with external (h...

  17. Efficacy of an autodisseminator of an entomopathogenic fungus, Isaria fumosorosea, to suppress Asian citrus psyllid, Diaphorina citri, under greenhouse conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP), transmits the causative agents of citrus greening disease or huanglongbing (HLB), the most devastating disease of citrus trees in the world today. ACP dwelling in noncommercial citrus (neighborhoods, commercial landscapes, etc.) can stymie area-wide management program...

  18. Molecular Effects of Irradiation (Cobalt-60) on the Control of Panonychus citri (Acari: Tetranychidae)

    PubMed Central

    Zhang, Ke; Luo, Lingyan; Chen, Xieting; Hu, Meiying; Hu, Qiongbo; Gong, Liang; Weng, Qunfang

    2015-01-01

    The effective dose of irradiation to control pest mites in quarantine has been studied extensively, but the molecular mechanisms underlying the effects of the irradiation on mites are largely unknown. In this study, exposure to 400 Gy of γ rays had significant (p < 0.05) effects on the adult survival, fecundity and egg viability of Panonychus citri. The irradiation caused the degradation of the DNA of P. citri adults and damaged the plasma membrane system of the egg, which led to condensed nucleoli and gathered yolk. Additionally, the transcriptomes and gene expression profiles between irradiated and non-irradiated mites were compared, and three digital gene expression libraries were assembled and analyzed. The differentially expressed genes were putatively involved in apoptosis, cell death and the cell cycle. Finally, the expression profiles of some related genes were studied using quantitative real-time PCR. Our study provides valuable information on the changes in the transcriptome of irradiated P. citri, which will facilitate a better understanding of the molecular mechanisms that cause the sterility induced by irradiation. PMID:26569230

  19. A Combination Treatment Using Ethyl Formate and Phosphine to Control Planococcus citri (Hemiptera: Pseudococcidae) on Pineapples.

    PubMed

    Yang, JeongOh; Park, Youngrong; Hyun, Ik-Hwa; Kim, Gil-Hah; Kim, Bong-Su; Lee, Byung-Ho; Ren, YongLin

    2016-12-01

    Citrus mealybug, Planococcus citri (Risso), is a known quarantine pest that is difficult to control with phosphine (PH3) or low concentrations of ethyl formate (EF), particularly at low temperatures. Methyl bromide (MB) is a fumigant used for quarantine and preshipment (QPS) that can eradicate target pests with short fumigation periods. However, MB, which is an ozone-depleting substance, is scheduled to be phased out in South Korea over the next decade. There is no ideal alternative fumigant to replace MB for QPS of perishable commodities. A laboratory study was conducted to compare the individual effects of EF and PH3 individually, and the effects of EF mixed with PH3 as an MB alternative for the control of P. citri adults, nymphs, and eggs. In comparison to treatments with EF and PH3 individually, EF mixed with PH3 resulted in high toxicity to all stages of P. citri. The eggs were more tolerant than the nymphs and adults. A mixed treatment of EF and PH3 achieved complete control of eggs infesting pineapples at concentrations of 25.1/1.0 (EF/PH3) mg/liter at 8 °C for 4 h of exposures. This new combined EF/PH3 fumigation technology could offer shorter exposure times and less damage to perishable commodities at low temperatures, and could potentially be extended to controlling other quarantine pests as a replacement treatment for fruit and vegetables in which methyl bromide is currently being used.

  20. Ligation-mediated PCR, a fast and reliable technique for insertion sequence-based typing of Xanthomonas citri pv. citri.

    PubMed

    Ngoc, Lan Bui Thi; Vernière, Christian; Belasque, José Júnior; Vital, Karine; Boutry, Sébastien; Gagnevin, Lionel; Pruvost, Olivier

    2008-11-01

    Asiatic citrus canker, caused by Xanthomonas citri pv. citri, is a major disease threatening citrus crops throughout the world. The most common methods for strain differentiation of this pathogen are repetitive element sequence-based PCR (rep-PCR) and pulsed field gel electrophoresis (PFGE), using rare-cutting restriction enzyme analysis. We developed a ligation-mediated PCR targeting three insertion sequences (IS-LM-PCR) present as several copies in the genome of the fully sequenced strain 306 of X. citri pv. citri. This technique amplifies DNA fragments between an insertion sequence element and an MspI restriction site. The analysis of strains can be conducted within 24 h, starting from very small amounts of bacterial DNA, which makes IS-LM-PCR much less labor-intensive than PFGE. We used IS-LM-PCR to analyze a collection of 66 strains of X. citri pv. citri from around the world. The overall reproducibility of IS-LM-PCR reached 98% in this data set and its discriminatory power was markedly superior than rep-PCR. We suggest that IS-LM-PCR could be used for the global surveillance of non-epidemiologically related strains of X. citri pv. citri.

  1. Bismerthiazol inhibits Xanthomonas citri subsp. citri growth and induces differential expression of citrus defense-related genes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus canker, caused by Xanthomonas citri ssp. citri (Xcc), is a serious disease and causes substantial economic losses to the citrus industry worldwide. The bactericide, bismerthiazol, has been widely used to control rice bacterial blight (Xanthomonas oryzae pv. oryzae). In this paper, we demonstr...

  2. Expression of Xylella fastidiosa RpfF in citrus disrupts signaling in Xanthomonas citri subsp. citri and thereby its virulence.

    PubMed

    Caserta, R; Picchi, S C; Takita, M A; Tomaz, J P; Pereira, W E L; Machado, M A; Ionescu, M; Lindow, S; De Souza, A A

    2014-11-01

    Xylella fastidiosa and Xanthomonas citri subsp. citri, that cause citrus variegated chlorosis (CVC) and citrus canker diseases, respectively, utilize diffusible signal factor (DSF) for quorum sensing. DSF, produced by RpfF, are similar fatty acids in both organisms, although a different set of genes is regulated by DSF in each species. Because of this similarity, Xylella fastidiosa DSF might be recognized and affect the biology of Xanthomonas citri. Therefore, transgenic Citrus sinensis and Carrizo citrange plants overexpressing the Xylella fastidiosa rpfF were inoculated with Xanthomonas citri and changes in symptoms of citrus canker were observed. X. citri biofilms formed only at wound sites on transgenic leaves and were thicker; however, bacteria were unable to break through the tissue and form pustules elsewhere. Although abundant growth of X. citri occurred at wound sites on inoculated transgenic leaves, little growth was observed on unwounded tissue. Genes in the DFS-responsive core in X. citri were downregulated in bacteria isolated from transgenic leaves. DSF-dependent expression of engA was suppressed in cells exposed to xylem sap from transgenic plants. Thus, altered symptom development appears to be due to reduced expression of virulence genes because of the presence of antagonists of DSF signaling in X. citri in rpfF-expressing plants.

  3. Dispersal of Xanthomonas citri subsp. citri bacteria downwind from harvested, infected fruit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus canker (Xanthomonas axonopodis pv. citri , Xac) is a bacterial disease that severely damages citrus crops. Its recent introduction to Florida has created difficulties with international and domestic trade and movement of citrus material. This study examined the potential dispersal of bacteri...

  4. Spiralin diversity within Iranian strains of Spiroplasma citri.

    PubMed

    Khanchezar, Amin; Béven, Laure; Izadpanah, Keramat; Salehi, Mohammad; Saillard, Colette

    2014-01-01

    The first-cultured and most-studied spiroplasma is Spiroplasma citri, the causal agent of citrus stubborn disease, one of the three plant-pathogenic, sieve-tube-restricted, and leafhopper vector-transmitted mollicutes. In Iranian Fars province, S. citri cultures were obtained from stubborn affected citrus trees, sesame and safflower plants, and from the leafhopper vector Circulifer haematoceps. Spiralin gene sequences from different S. citri isolates were amplified by PCR, cloned, and sequenced. Phylogenetic trees based on spiralin gene sequence showed diversity and indicated the presence of three clusters among the S. citri strains. Comparison of the amino acid sequences of eleven spiralins from Iranian strains and those from the reference S. citri strain GII-3 (241 aa), Palmyre strain (242 aa), Spiroplasma kunkelii (240 aa), and Spiroplasma phoeniceum (237 aa) confirmed the conservation of general features of the protein. However, the spiralin of an S. citri isolate named Shiraz I comprised 346 amino acids and showed a large duplication of the region comprised between two short repeats previously identified in S. citri spiralins. We report in this paper the spiralin diversity in Spiroplasma strains from southern Iran and for the first time a partial internal duplication of the spiralin gene.

  5. Selection of Small Synthetic Antimicrobial Peptides Inhibiting Xanthomonas citri subsp. citri Causing Citrus Canker

    PubMed Central

    Choi, Jeahyuk; Park, Euiho; Lee, Se-Weon; Hyun, Jae-Wook; Baek, Kwang-Hyun

    2017-01-01

    Citrus canker disease decreases the fruit quality and yield significantly, furthermore, emerging of streptomycin-resistant pathogens threatens the citrus industry seriously because of a lack of proper control agents. Small synthetic antimicrobial peptides (AMPs) could be a promising alternative. Fourteen hexapeptides were selected by using positional scanning of synthetic peptide combinatorial libraries. Each hexapeptide showed different antimicrobial spectrum against Bacillus, Pseudomonas, Xanthomonas, and Candida species. Intriguingly, BHC10 showed bactericidal activity exclusively on Xanthomonas citri subsp. citri (Xcc), while BHC7 was none-active exclusively against two Pseudomonas spp. at concentration of 100 μg/ml suggesting potential selectivity constrained in hexapeptide frame. Three hexapeptides, BHC02, 06 and 11, showed bactericidal activities against various Xcc strains at concentration of 10 μg/ml. When they were co-infiltrated with pathogens into citrus leaves the disease progress was suppressed significantly. Further study would be needed to confirm the actual disease control capacity of the selected hexapeptides. PMID:28167892

  6. Genetic variation of Spiroplasma citri populations in California revealed by two genomic loci

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus stubborn disease (CSD), known to be present in California since 1915, was confirmed to be caused by Spiroplasma citri in 1972. Hosts of S. citri include citrus and a wide range of annual weeds, ornamentals and crops such as carrots and sesame. Genetic variation of S. citri in California was e...

  7. Asian Citrus Psyllid Expression Profiles Suggest Candidatus Liberibacter Asiaticus-Mediated Alteration of Adult Nutrition and Metabolism, and of Nymphal Development and Immunity

    PubMed Central

    He, Ruifeng; Nelson, William; Yin, Guohua; Cicero, Joseph M.; Willer, Mark; Kim, Ryan; Kramer, Robin; May, Greg A.; Crow, John A.; Soderlund, Carol A.; Gang, David R.; Brown, Judith K.

    2015-01-01

    The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is the insect vector of the fastidious bacterium Candidatus Liberibacter asiaticus (CLas), the causal agent of citrus greening disease, or Huanglongbing (HLB). The widespread invasiveness of the psyllid vector and HLB in citrus trees worldwide has underscored the need for non-traditional approaches to manage the disease. One tenable solution is through the deployment of RNA interference technology to silence protein-protein interactions essential for ACP-mediated CLas invasion and transmission. To identify psyllid interactor-bacterial effector combinations associated with psyllid-CLas interactions, cDNA libraries were constructed from CLas-infected and CLas-free ACP adults and nymphs, and analyzed for differential expression. Library assemblies comprised 24,039,255 reads and yielded 45,976 consensus contigs. They were annotated (UniProt), classified using Gene Ontology, and subjected to in silico expression analyses using the Transcriptome Computational Workbench (TCW) (http://www.sohomoptera.org/ACPPoP/). Functional-biological pathway interpretations were carried out using the Kyoto Encyclopedia of Genes and Genomes databases. Differentially expressed contigs in adults and/or nymphs represented genes and/or metabolic/pathogenesis pathways involved in adhesion, biofilm formation, development-related, immunity, nutrition, stress, and virulence. Notably, contigs involved in gene silencing and transposon-related responses were documented in a psyllid for the first time. This is the first comparative transcriptomic analysis of ACP adults and nymphs infected and uninfected with CLas. The results provide key initial insights into host-parasite interactions involving CLas effectors that contribute to invasion-virulence, and to host nutritional exploitation and immune-related responses that appear to be essential for successful ACP-mediated circulative, propagative CLas transmission. PMID

  8. Acaricidal activity against Panonychus citri and active ingredient of the mangrove plant Cerbera manghas.

    PubMed

    Deng, Yecheng; Yongmei Liao; Li, Jingjing; Yang, Linlin; Zhong, Hui; Zhou, Qiuyan; Qing, Zhen

    2014-09-01

    Cerbera manghas is a mangrove plant which possesses comprehensive biological activities. A great deal of research has been undertaken on the chemical constituents and medical functions of C. manghas; insecticidal and antifungal activities have also been reported, but the acaricidal activity has not been studied. In our study, the acaricidal activity and active substances of C. manghas were investigated using a spray method, which showed that the methanol extracts of the fruit, twigs and leaves exhibited contact activity against female adults of Panonychus citri, with LC50 values at 24 h of 3.39 g L(-1), 4.09 g L(-1) and 4.11 g L(-1), respectively. An acaricidal compound was isolated from C. manghas by an activity-guided isolation method, and identified as (-)-17β-neriifolin, which is a cardiac glycoside. (-)-17β-Neriifolin revealed high contact activity against female adults, nymphae, larvae and eggs of P. citri, with LC50 values at 24 h of 0.28 g L(-1), 0.29 g L(-1), 0.28 g L(-1) and 1.45 g L(-1), respectively.

  9. A MLVA genotyping scheme for global surveillance of the citrus pathogen Xanthomonas citri pv. citri suggests a worldwide geographical expansion of a single genetic lineage.

    PubMed

    Pruvost, Olivier; Magne, Maxime; Boyer, Karine; Leduc, Alice; Tourterel, Christophe; Drevet, Christine; Ravigné, Virginie; Gagnevin, Lionel; Guérin, Fabien; Chiroleu, Frédéric; Koebnik, Ralf; Verdier, Valérie; Vernière, Christian

    2014-01-01

    MultiLocus Variable number of tandem repeat Analysis (MLVA) has been extensively used to examine epidemiological and evolutionary issues on monomorphic human pathogenic bacteria, but not on bacterial plant pathogens of agricultural importance albeit such tools would improve our understanding of their epidemiology, as well as of the history of epidemics on a global scale. Xanthomonas citri pv. citri is a quarantine organism in several countries and a major threat for the citrus industry worldwide. We screened the genomes of Xanthomonas citri pv. citri strain IAPAR 306 and of phylogenetically related xanthomonads for tandem repeats. From these in silico data, an optimized MLVA scheme was developed to assess the global diversity of this monomorphic bacterium. Thirty-one minisatellite loci (MLVA-31) were selected to assess the genetic structure of 129 strains representative of the worldwide pathological and genetic diversity of X. citri pv. citri. Based on Discriminant Analysis of Principal Components (DAPC), four pathotype-specific clusters were defined. DAPC cluster 1 comprised strains that were implicated in the major geographical expansion of X. citri pv. citri during the 20th century. A subset of 12 loci (MLVA-12) resolved 89% of the total diversity and matched the genetic structure revealed by MLVA-31. MLVA-12 is proposed for routine epidemiological identification of X. citri pv. citri, whereas MLVA-31 is proposed for phylogenetic and population genetics studies. MLVA-31 represents an opportunity for international X. citri pv. citri genotyping and data sharing. The MLVA-31 data generated in this study was deposited in the Xanthomonas citri genotyping database (http://www.biopred.net/MLVA/).

  10. Viruses of Spiroplasma citri and their possible effects on pathogenicity.

    PubMed Central

    Townsend, R.

    1983-01-01

    Strains of Spiroplasma citri are persistently infected by viruses which have been separated into three groups on the basis of their morphology. The properties of each group are reviewed. Viruses normally only appear in spiroplasma cultures but recently all three types of particle have been identified in cells of a single strain of S. citri within an infected plant. Replication of a short-tailed polyhedral virus SP-V3 (ai) appears to be correlated with unusually mild symptom expression. Introduction of the virus with its host into plants already infected with a severe and potentially lethal strain of S. citri results in a marked suppression of symptoms and a reduction in the number of spiroplasmas. Images FIG. 1 FIG. 2 FIG. 3 FIG. 4 FIG. 5 FIG. 6 PMID:6382829

  11. treA Codifies for a Trehalase with Involvement in Xanthomonas citri subsp. citri Pathogenicity

    PubMed Central

    Alexandrino, André Vessoni; Goto, Leandro Seiji; Novo-Mansur, Maria Teresa Marques

    2016-01-01

    Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri (Xcc), is a severe disease of citrus. Xcc presents broad spectrum of citrus hosts including economically important species whereas X. fuscans subsp. aurantifolii–type C (XauC) causes a milder disease and only infects Citrus aurantifolia. Trehalase catalyzes hydrolysis of the disaccharide trehalose, a sugar that has been reported to be related to Xcc pathogenicity. We expressed the recombinant gene product and assessed Xcc trehalase structural and kinetics data. The recombinant protein presented 42.7% of secondary structures in α-helix and 13% in β-sheets, no quaternary structure in solution, and Michaelis-Menten constant (KM) of 0.077 mM and Vmax 55.308 μMol glucose.min-1.mg protein-1 for trehalose. A Xcc mutant strain (XccΔtreA) was produced by gene deletion from Xcc genome. Enzymatic activity of trehalase was determined in Xcc, XauC and XccΔtreA cellular lysates, showing the highest values for XauC in in vitro infective condition and no activity for XccΔtreA. Finally, leaves of Citrus aurantifolia infected with XccΔtreA showed much more drenching and necrosis than those infected by wild type Xcc. We concluded that trehalase contributes to alleviate bacterial virulence and that inability for trehalose hydrolysis may promote higher Xcc infectivity. PMID:27611974

  12. Bioactive Organocopper Compound from Pseudomonas aeruginosa Inhibits the Growth of Xanthomonas citri subsp. citri

    PubMed Central

    de Oliveira, Admilton G.; Spago, Flavia R.; Simionato, Ane S.; Navarro, Miguel O. P.; da Silva, Caroline S.; Barazetti, André R.; Cely, Martha V. T.; Tischer, Cesar A.; San Martin, Juca A. B.; de Jesus Andrade, Célia G. T.; Novello, Cláudio R.; Mello, João C. P.; Andrade, Galdino

    2016-01-01

    Citrus canker is a very destructive disease of citrus species. The challenge is to find new compounds that show strong antibiotic activity and low toxicity to plants and the environment. The objectives of the present study were (1) to extract, purify and evaluate the secondary metabolites with antibiotic activity produced by Pseudomonas aeruginosa LV strain in vitro against Xanthomonas citri subsp. citri (strain 306), (2) to determine the potential of semi-purified secondary metabolites in foliar application to control citrus canker under greenhouse conditions, and (3) to identify antibiotic activity in orange leaf mesophyll infected with strain 306, by electron microscopy. Two pure bioactive compounds were isolated, an organocopper antibiotic compound (OAC) and phenazine-1-carboxamide. Phenazine-1-carboxamide did not show any antibiotic activity under the experimental conditions used in this study. The OAC showed a high level of antibiotic activity with a minimum inhibitory concentration of 0.12 μg mL-1. In greenhouse tests for control of citrus canker in orange trees, the semi-purified fraction F3d reduced lesion formation by about 97%. The concentration used was 500 times lower than that for the recommended commercial copper-based product. Electron microscopy showed that F3d altered the exopolysaccharide matrix and caused cell lysis of the pathogen inside the citrus canker lesions. These results suggest that secondary metabolites produced by inducing P. aeruginosa LV strain have a high potential to be used as a bioproduct to control citrus canker. PMID:26903992

  13. Ectopic accumulation of linalool confers resistance to Xanthomonas citri subsp. citri in transgenic sweet orange plants.

    PubMed

    Shimada, Takehiko; Endo, Tomoko; Rodríguez, Ana; Fujii, Hiroshi; Goto, Shingo; Matsuura, Takakazu; Hojo, Yuko; Ikeda, Yoko; Mori, Izumi C; Fujikawa, Takashi; Peña, Leandro; Omura, Mitsuo

    2017-01-27

    In order to clarify whether high linalool content in citrus leaves alone induces strong field resistance to citrus canker caused by Xanthomonas citri subsp. citri (Xcc), and to assess whether this trait can be transferred to a citrus type highly sensitive to the bacterium, transgenic 'Hamlin' sweet orange (Citrus sinensis L. Osbeck) plants over-expressing a linalool synthase gene (CuSTS3-1) were generated. Transgenic lines (LIL) with the highest linalool content showed strong resistance to citrus canker when spray inoculated with the bacterium. In LIL plants inoculated by wounding (multiple-needle inoculation), the linalool level was correlated with the repression of the bacterial titer and up-regulation of defense-related genes. The exogenous application of salicylic acid, methyl jasmonate or linalool triggered responses similar to those constitutively induced in LIL plants. The linalool content in Ponkan mandarin leaves was significantly higher than that of leaves from six other representative citrus genotypes with different susceptibilities to Xcc We propose that linalool-mediated resistance might be unique to citrus tissues accumulating large amounts of volatile organic compounds in oil cells. Linalool might act not only as a direct antibacterial agent, but also as a signal molecule involved in triggering a non-host resistance response against Xcc.

  14. Rapid and accurate identification of Xanthomonas citri subspecies citri by fluorescence in situ hybridization.

    PubMed

    Waite, D W; Griffin, R; Taylor, R; George, S

    2016-11-01

    Citrus canker is an economically important disease caused by the bacterial pathogen Xanthomonas citri subsp. citri (Xcc). This organism targets a wide range of citrus plants, including sweet orange, grapefruit, lemon and lime. As Xcc is spread by environmental factors such as wind and rain, it is difficult to control its movement once the disease has established. In order to facilitate monitoring of citrus canker we sought to design a novel diagnostic protocol based on fluorescence in situ hybridization (FISH) for identification of bacterial cells directly from canker pustules without cultivation or DNA extraction. This method was validated for specificity against a range of Xanthomonas species and strains. We show that our assay is extremely rapid (typically requiring between 2 and 3 h), and possesses a similar specificity to existing PCR diagnostic tools. The sensitivity of the assay is comparable to that of an existing PCR-based technique and sufficient for identifying Xcc in symptomatic plant material. The method is easily transferable to diagnosticians without prior experience using FISH.

  15. Bioactive Organocopper Compound from Pseudomonas aeruginosa Inhibits the Growth of Xanthomonas citri subsp. citri.

    PubMed

    de Oliveira, Admilton G; Spago, Flavia R; Simionato, Ane S; Navarro, Miguel O P; da Silva, Caroline S; Barazetti, André R; Cely, Martha V T; Tischer, Cesar A; San Martin, Juca A B; de Jesus Andrade, Célia G T; Novello, Cláudio R; Mello, João C P; Andrade, Galdino

    2016-01-01

    Citrus canker is a very destructive disease of citrus species. The challenge is to find new compounds that show strong antibiotic activity and low toxicity to plants and the environment. The objectives of the present study were (1) to extract, purify and evaluate the secondary metabolites with antibiotic activity produced by Pseudomonas aeruginosa LV strain in vitro against Xanthomonas citri subsp. citri (strain 306), (2) to determine the potential of semi-purified secondary metabolites in foliar application to control citrus canker under greenhouse conditions, and (3) to identify antibiotic activity in orange leaf mesophyll infected with strain 306, by electron microscopy. Two pure bioactive compounds were isolated, an organocopper antibiotic compound (OAC) and phenazine-1-carboxamide. Phenazine-1-carboxamide did not show any antibiotic activity under the experimental conditions used in this study. The OAC showed a high level of antibiotic activity with a minimum inhibitory concentration of 0.12 μg mL(-1). In greenhouse tests for control of citrus canker in orange trees, the semi-purified fraction F3d reduced lesion formation by about 97%. The concentration used was 500 times lower than that for the recommended commercial copper-based product. Electron microscopy showed that F3d altered the exopolysaccharide matrix and caused cell lysis of the pathogen inside the citrus canker lesions. These results suggest that secondary metabolites produced by inducing P. aeruginosa LV strain have a high potential to be used as a bioproduct to control citrus canker.

  16. Characterization of the Asian Citrus Psyllid Transcriptome

    PubMed Central

    Reese, Justin; Christenson, Matthew K.; Leng, Nan; Saha, Surya; Cantarel, Brandi; Lindeberg, Magdalen; Tamborindeguy, Cecilia; MacCarthy, Justin; Weaver, Daniel; Trease, Andrew J.; Ready, Steven V.; Davis, Vincent M.; McCormick, Courtney; Haudenschild, Christian; Han, Shunsheng; Johnson, Shannon L.; Shelby, Kent S.; Huang, Hong; Bextine, Blake R.; Shatters, Robert G.; Hall, David G.; Davis, Paul H.; Hunter, Wayne B.

    2014-01-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is a vector for the causative agents of Huanglongbing, which threatens citrus production worldwide. This study reports and discusses the first D. citri transcriptomes, encompassing the three main life stages of D. citri, egg, nymph and adult. The transcriptomes were annotated using Gene Ontology (GO) and insecticide-related genes within each life stage were identified to aid the development of future D. citri insecticides. Transcriptome assemblies and other sequence data are available for download at the International Asian Citrus Psyllid Genome Consortium website [http://psyllid.org/download] and at NCBI [http://www.ncbi.nlm.nih.gov/bioproject/29447]. PMID:24511328

  17. Non-Host Defense Response in a Novel Arabidopsis-Xanthomonas citri subsp. citri Pathosystem

    PubMed Central

    An, Chuanfu; Mou, Zhonglin

    2012-01-01

    Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is one of the most destructive diseases of citrus. Progress of breeding citrus canker-resistant varieties is modest due to limited resistant germplasm resources and lack of candidate genes for genetic manipulation. The objective of this study is to establish a novel heterologous pathosystem between Xcc and the well-established model plant Arabidopsis thaliana for defense mechanism dissection and resistance gene identification. Our results indicate that Xcc bacteria neither grow nor decline in Arabidopsis, but induce multiple defense responses including callose deposition, reactive oxygen species and salicylic aicd (SA) production, and defense gene expression, indicating that Xcc activates non-host resistance in Arabidopsis. Moreover, Xcc-induced defense gene expression is suppressed or attenuated in several well-characterized SA signaling mutants including eds1, pad4, eds5, sid2, and npr1. Interestingly, resistance to Xcc is compromised only in eds1, pad4, and eds5, but not in sid2 and npr1. However, combining sid2 and npr1 in the sid2npr1 double mutant compromises resistance to Xcc, suggesting genetic interactions likely exist between SID2 and NPR1 in the non-host resistance against Xcc in Arabidopsis. These results demonstrate that the SA signaling pathway plays a critical role in regulating non-host defense against Xcc in Arabidopsis and suggest that the SA signaling pathway genes may hold great potential for breeding citrus canker-resistant varieties through modern gene transfer technology. PMID:22299054

  18. Resistance to citrus canker induced by a variant of Xanthomonas citri ssp. citri is associated with a hypersensitive cell death response involving autophagy-associated vacuolar processes.

    PubMed

    Roeschlin, Roxana A; Favaro, María A; Chiesa, María A; Alemano, Sergio; Vojnov, Adrián A; Castagnaro, Atilio P; Filippone, María P; Gmitter, Frederick G; Gadea, José; Marano, María R

    2016-09-20

    Xanthomonas citri ssp. citri (X. citri) is the causal agent of Asiatic citrus canker, a disease that seriously affects most commercially important Citrus species worldwide. We have identified previously a natural variant, X. citri A(T) , that triggers a host-specific defence response in Citrus limon. However, the mechanisms involved in this canker disease resistance are unknown. In this work, the defence response induced by X. citri A(T) was assessed by transcriptomic, physiological and ultrastructural analyses, and the effects on bacterial biofilm formation were monitored in parallel. We show that X. citri A(T) triggers a hypersensitive response associated with the interference of biofilm development and arrest of bacterial growth in C. limon. This plant response involves an extensive transcriptional reprogramming, setting in motion cell wall reinforcement, the oxidative burst and the accumulation of salicylic acid (SA) and phenolic compounds. Ultrastructural analyses revealed subcellular changes involving the activation of autophagy-associated vacuolar processes. Our findings show the activation of SA-dependent defence in response to X. citri A(T) and suggest a coordinated regulation between the SA and flavonoid pathways, which is associated with autophagy mechanisms that control pathogen invasion in C. limon. Furthermore, this defence response protects C. limon plants from disease on subsequent challenges by pathogenic X. citri. This knowledge will allow the rational exploitation of the plant immune system as a biotechnological approach for the management of the disease.

  19. Reaction of detached leaves of different varieties of sweet orange (Citrus sinensis L. Osbeck) to inoculation with Xanthomonas citri subsp. citri (ex Hasse) Gabriel et al.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Asiatic citrus canker (ACC) (caused by Xanthomonas citri subsp citri, Xcc) is a major disease of citrus in wet tropical and subtropical production regions. Screening for resistance is important to breeding programs. The objective of this study was to evaluate a detached leaf method to compare nine d...

  20. The effect of wind on dispersal of splash-borne Xanthomonas citri subsp citri at different heights and distances downwind of canker-infected grapefruit trees

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xanthomonas citri subsp citri (Xcc), which causes citrus canker, is a major pathogen of grapefruit and other canker-susceptible citrus species and cultivars grown in Florida and elsewhere. It is dispersed by rain splash, and wind promotes the dispersal of the pathogen. The aim of this study was to e...

  1. Wind speed effects on the quantity of Xanthomonas citri subsp. citri dispersed downwind from canopies of grapefruit trees infected with citrus canker

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The epidemic of citrus canker (Xanthomonas citri subsp. citri, Xcc) in Florida continues to expand since termination of the eradication program in 2006. Storms are known to be associated with disease spread, but little information exists on the interaction of fundamental physical and biological proc...

  2. Processess involved in the dispersal of Xanthomonas citri pv. citri from canker-infected citrus canopies, and in the infection of citrus foliage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus canker (Xanthomonas citri subsp. citri, Xcc) is now considered endemic in Florida, and epidemics result in yield loss and market penalties both in Florida and elsewhere, where the pathogen occurs and susceptible citrus is cultivated. The bacterium is dispersed in rain splash, and storms with...

  3. Processes involved in the dispersal of Xanthomonas citri pv. citri from canker-infectd citrus canopies, and in the infection of citrus foliage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus canker (Xanthomonas citri subsp. citri, Xcc) is now considered endemic in Florida, and epidemics result in yield loss and market penalties both in Florida, and elsewhere where the pathogen occurs, and susceptible citrus is cultivated. The bacterium is dispersed in rain splash, and storms wit...

  4. The epidemiological significance of post-packinghouse survival of Xanthomonas citri ssp. citri for dissemination of Asiatic citrus canker via infected fruit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The risk of introduction of Xanthomonas citri spp. citri (Xcc) to new, unaffected citrus producing areas is a major concern for those citrus industries attempting to remain free of citrus canker. Citrus fruit, as a potential pathway for Xcc to enter and become established in these areas, is assumed...

  5. Amplified fragment length polymorphism and multilocus sequence analysis-based genotypic relatedness among pathogenic variants of Xanthomonas citri pv. citri and Xanthomonas campestris pv. bilvae.

    PubMed

    Bui Thi Ngoc, Lan; Vernière, Christian; Jouen, Emmanuel; Ah-You, Nathalie; Lefeuvre, Pierre; Chiroleu, Frédéric; Gagnevin, Lionel; Pruvost, Olivier

    2010-03-01

    Three pathogenic variants (i.e. pathotypes) have been described within Xanthomonas citri pv. citri, the causal agent of Asiatic citrus canker. Pathotype A strains naturally infect a wide range of Citrus species and members of some related genera. In contrast, pathotypes A* and A(w) have narrow host ranges within the genus Citrus and have been isolated from Mexican lime (Citrus aurantifolia L.) and from Mexican lime and alemow (Citrus macrophylla L.), respectively. We used amplified fragment length polymorphism (AFLP) and multilocus sequence analysis (MLSA) based on four partial housekeeping gene sequences (atpD, dnaK, efp and gyrB ) for the genotypic classification of Xanthomonas citri pv. citri and the poorly characterized citrus pathogen Xanthomonas campestris pv. bilvae. A Mantel test showed that genetic distances derived from AFLP and MLSA were highly correlated. X. campestris pv. bilvae showed a close relatedness to the type strain of X. citri, indicating that this pathovar should be reclassified as X. citri pv. bilvae. All pathotype A* and A(w) strains were most closely related to X. citri pv. citri strains with a wide host range (pathotype A), confirming previous DNA-DNA hybridization data. Pathotype A(w) should be considered a junior synonym of pathotype A* on the basis of pathogenicity tests, AFLP, MLSA and PCR using pathovar-specific primers. Evolutionary genome divergences computed from AFLP data suggested that pathotype A* (including A(w) strains) is a group of strains that shows a wider genetic diversity than pathotype A.

  6. Comparative ultrastructure of nonwounded Mexican lime and Yuzu leaves infected with the citrus canker bacterium Xanthomonas citri pv. citri.

    PubMed

    Lee, In Jung; Kim, Ki Woo; Hyun, Jae Wook; Lee, Yong Hoon; Park, Eun Woo

    2009-07-01

    Ultrastructural aspects of citrus canker development were investigated in nonwounded leaves of citrus species by transmission electron microscopy (TEM). A susceptible species Mexican lime and a resistant species Yuzu were spray-inoculated with a virulent strain of Xanthomonas citri pv. citri. Initial symptoms occurred on Mexican lime approximately 9 days after inoculation, whereas they appeared on Yuzu mostly 11 days after inoculation. In Mexican lime leaves, the bacterial invasion was usually accompanied by host cell wall dissolution and cellular disruption. Fibrillar materials from degenerated cell walls were usually found in intercellular spaces. Damaged host cells with necrotic cytoplasm showed the localized separation of plasma membrane from the cell wall. Bacterial multiplication and electron-transparent capsule-like structures around bacteria were commonly observed. Meanwhile, cell wall protuberances were prominent outside host cell walls in response to bacterial invasion in Yuzu leaves. Occlusion of intercellular spaces was also formed by the fusion of two or more individual cell wall protuberances originated from two adjacent host cells. Papillae-like materials accumulated locally within host cells in close proximity to bacteria. Some bacteria were found to be undergoing degeneration in xylem vessels. Also, the shrunken, inactive bacteria were surrounded by electron-translucent fibrillar materials in intercellular spaces, implying bacterial immobilization. These cellular responses are thought to be the consequences of defense responses of Yuzu leaves to invading bacteria. In both citrus species, X. citri pv. citri contained polyphosphate bodies showing electron-dense and elliptical structures in cytoplasm.

  7. Biological control of Asian citrus psyllid (Diaphorina citri) in Florida by the parasitoid Tamarixia radiata in urban plantings of orange jasmine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid is an important invasive citrus pest in the United States because it vectors a bacterium responsible for a devastating disease of citrus known as huanglongbing. A parasitoid of the psyllid, Tamarixia radiata (Hymenoptera: Eulophidae), was imported from Southeast Asia and re...

  8. Association of ‘Candidatus Liberibacter asiaticus’, the causal agent of citrus huanglongbing in Murraya paniculata and Diaphorina citri in Thailand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Orange jasmine, Murraya paniculata, is a preferred alternative host for the Asian citrus psyllid, the primary vector of citrus Huanglongbing (HLB) disease caused by ‘Candidatus Liberibacter asiaticus’ (Las). M. paniculata plant samples and psyllids on the Murraya plants from ten diverse geographical...

  9. Diversity of the citrus HLB bacterium, ‘Candidatus Liberibacter asiaticus’, in psyllids (Diaphorina citri) collected from Murraya paniculata and citrus spp. in Thailand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ‘Candidatus Liberibacter asiaticus’ (Las) is a phloem inhabiting bacterium that causes huanglongbing disease (HLB), also known as citrus greening associated with three species of a-Proteobacteria in the genus ‘Candidatus Liberibacter sp’. Prophage is an important genetic element of bacterial genomes...

  10. Herbivory by the insect diaphorina citri induces greater change in citrus plant volatile profile than does infection by the bacterium, Candidatus Liberibacter asiaticus

    PubMed Central

    Hijaz, Faraj; El-Shesheny, Ibrahim; Killiny, Nabil

    2013-01-01

    The volatile organic compound (VOC) profile in plant leaves often changes after biotic and abiotic stresses. Monitoring changes in VOCs in plant leaves could provide valuable information about multitrophic interactions. In the current study, we investigated the effect of Asian citrus psyllid (ACP) infestation, citrus greening pathogen (Candidatus Liberibacter asiaticus [CLas]) infection, and simultaneous attack by ACP and CLas on the VOC content of citrus leaves. Leaf volatiles were extracted using hexane and analyzed with gas chromatography-mass spectrometry (GC-MS). Although ACP is a phloem-sucking insect that causes minimal damage to plant tissues, the relative amount of 21 out of the 27 VOCs increased 2- to 10-fold in ACP-infested plants. The relative amount of d-limonene, β-phelandrene, citronellal, and undecanal were increased 4- to 20- fold in CLas-infected plants. A principle component analysis (PCA) and cluster analysis (CA) showed that VOC patterns of ACP-infested and CLas-infected plants were different from each other and were also different from the controls, while the VOC pattern of double-attacked plants was more like that of the controls than that of ACP-infested or CLas-infected plants. VOC amounts from leaves were compromised when plants were attacked by ACP and CLas. The results of this study showed that a simple direct extraction of citrus leaf volatiles could be successfully used to discriminate between healthy and CLas-infected plants. Information about the effects of insect and pathogen attack on the VOC content profile of plants might contribute to a better understanding of biotic stress. PMID:23857364

  11. Xylan utilization regulon in Xanthomonas citri pv. citri Strain 306: gene expression and utilization of oligoxylosides.

    PubMed

    Chow, V; Shantharaj, D; Guo, Y; Nong, G; Minsavage, G V; Jones, J B; Preston, J F

    2015-03-01

    Xanthomonas citri pv. citri strain 306 (Xcc306), a causative agent of citrus canker, produces endoxylanases that catalyze the depolymerization of cell wall-associated xylans. In the sequenced genomes of all plant-pathogenic xanthomonads, genes encoding xylanolytic enzymes are clustered in three adjacent operons. In Xcc306, these consecutive operons contain genes encoding the glycoside hydrolase family 10 (GH10) endoxylanases Xyn10A and Xyn10C, the agu67 gene, encoding a GH67 α-glucuronidase (Agu67), the xyn43E gene, encoding a putative GH43 α-l-arabinofuranosidase, and the xyn43F gene, encoding a putative β-xylosidase. Recombinant Xyn10A and Xyn10C convert polymeric 4-O-methylglucuronoxylan (MeGXn) to oligoxylosides methylglucuronoxylotriose (MeGX3), xylotriose (X3), and xylobiose (X2). Xcc306 completely utilizes MeGXn predigested with Xyn10A or Xyn10C but shows little utilization of MeGXn. Xcc306 with a deletion in the gene encoding α-glucuronidase (Xcc306 Δagu67) will not utilize MeGX3 for growth, demonstrating the role of Agu67 in the complete utilization of GH10-digested MeGXn. Preferential growth on oligoxylosides compared to growth on polymeric MeGXn indicates that GH10 xylanases, either secreted by Xcc306 in planta or produced by the plant host, generate oligoxylosides that are processed by Xyn10 xylanases and Agu67 residing in the periplasm. Coordinate induction by oligoxylosides of xyn10, agu67, cirA, the tonB receptor, and other genes within these three operons indicates that they constitute a regulon that is responsive to the oligoxylosides generated by the action of Xcc306 GH10 xylanases on MeGXn. The combined expression of genes in this regulon may allow scavenging of oligoxylosides derived from cell wall deconstruction, thereby contributing to the tissue colonization and/or survival of Xcc306 and, ultimately, to plant disease.

  12. Xylan Utilization Regulon in Xanthomonas citri pv. citri Strain 306: Gene Expression and Utilization of Oligoxylosides

    PubMed Central

    Chow, V.; Shantharaj, D.; Guo, Y.; Nong, G.; Minsavage, G. V.; Jones, J. B.

    2015-01-01

    Xanthomonas citri pv. citri strain 306 (Xcc306), a causative agent of citrus canker, produces endoxylanases that catalyze the depolymerization of cell wall-associated xylans. In the sequenced genomes of all plant-pathogenic xanthomonads, genes encoding xylanolytic enzymes are clustered in three adjacent operons. In Xcc306, these consecutive operons contain genes encoding the glycoside hydrolase family 10 (GH10) endoxylanases Xyn10A and Xyn10C, the agu67 gene, encoding a GH67 α-glucuronidase (Agu67), the xyn43E gene, encoding a putative GH43 α-l-arabinofuranosidase, and the xyn43F gene, encoding a putative β-xylosidase. Recombinant Xyn10A and Xyn10C convert polymeric 4-O-methylglucuronoxylan (MeGXn) to oligoxylosides methylglucuronoxylotriose (MeGX3), xylotriose (X3), and xylobiose (X2). Xcc306 completely utilizes MeGXn predigested with Xyn10A or Xyn10C but shows little utilization of MeGXn. Xcc306 with a deletion in the gene encoding α-glucuronidase (Xcc306 Δagu67) will not utilize MeGX3 for growth, demonstrating the role of Agu67 in the complete utilization of GH10-digested MeGXn. Preferential growth on oligoxylosides compared to growth on polymeric MeGXn indicates that GH10 xylanases, either secreted by Xcc306 in planta or produced by the plant host, generate oligoxylosides that are processed by Xyn10 xylanases and Agu67 residing in the periplasm. Coordinate induction by oligoxylosides of xyn10, agu67, cirA, the tonB receptor, and other genes within these three operons indicates that they constitute a regulon that is responsive to the oligoxylosides generated by the action of Xcc306 GH10 xylanases on MeGXn. The combined expression of genes in this regulon may allow scavenging of oligoxylosides derived from cell wall deconstruction, thereby contributing to the tissue colonization and/or survival of Xcc306 and, ultimately, to plant disease. PMID:25595763

  13. Unravelling potential virulence factor candidates in Xanthomonas citri. subsp. citri by secretome analysis

    PubMed Central

    Ferro, Jesus A.; Soares, Marcia R.R.; Laia, Marcelo L.; de Oliveira, Julio C.F.; Ferro, Maria Ines T.

    2016-01-01

    Citrus canker is a major disease affecting citrus production in Brazil. It’s mainly caused by Xanthomonas citri subsp. citri strain 306 pathotype A (Xac). We analysed the differential expression of proteins secreted by wild type Xac and an asymptomatic mutant for hrpB4 (ΔhrpB4) grown in Nutrient Broth (NB) and a medium mimicking growth conditions in the plant (XAM1). This allowed the identification of 55 secreted proteins, of which 37 were secreted by both strains when cultured in XAM1. In this secreted protein repertoire, the following stand out: Virk, Polyphosphate-selective porin, Cellulase, Endoglucanase, Histone-like protein, Ribosomal proteins, five hypothetical proteins expressed only in the wild type strain, Lytic murein transglycosylase, Lipoprotein, Leucyl-tRNA synthetase, Co-chaperonin, Toluene tolerance, C-type cytochrome biogenesis membrane protein, Aminopeptidase and two hypothetical proteins expressed only in the ΔhrpB4 mutant. Furthermore, Peptidoglycan-associated outer membrane protein, Regulator of pathogenicity factor, Outer membrane proteins, Endopolygalacturonase, Chorismate mutase, Peptidyl-prolyl cis-trans isomerase and seven hypothetical proteins were detected in both strains, suggesting that there was no relationship with the secretion mediated by the type III secretory system, which is not functional in the mutant strain. Also worth mentioning is the Elongation factor Tu (EF-Tu), expressed only the wild type strain, and Type IV pilus assembly protein, Flagellin (FliC) and Flagellar hook-associated protein, identified in the wild-type strain secretome when grown only in NB. Noteworthy, that FliC, EF-Tu are classically characterized as PAMPs (Pathogen-associated molecular patterns), responsible for a PAMP-triggered immunity response. Therefore, our results highlight proteins potentially involved with the virulence. Overall, we conclude that the use of secretome data is a valuable approach that may bring more knowledge of the biology of

  14. Improved real-time PCR diagnosis of citrus stubborn disease by targeting prophage genes of Spiroplasma citri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spiroplasma citri is a phloem-limited bacterium causing citrus stubborn disease (CSD). Isolation and culturing of S. citri is difficult and time consuming. Current detection methods use polymerase chain reaction (PCR) assays with primers developed from sequences of S. citri house-keeping genes. In c...

  15. Synthetic substrate-borne vibrational signals that elicit Asian citrus psyllid communicatory and search responses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian Citrus Psyllid (ACP), Diaphorina citri Kuwayama, vectors a harmful bacterium, Candidatus Liberibacter asiaticus, that causes huanglongbing, an economically devastating disease of citrus. Adult male and female ACP transmit vibratory communication signals over 10-50-cm distances within their...

  16. Greenhouse investigations on the effect of guava on infestations of Asian citrus psyllid in grapefruit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reports from Vietnam indicate interplanting guava with citrus dramatically reduces infestations of Asian citrus psyllid (Diaphorina citri). We therefore conducted greenhouse studies to assess the effect of different guava cultivars on adult psyllids. The effects of cotton and tomato were also evalu...

  17. The Effect of Ultraviolet-A Radiation Exposure on the Reproductive Ability, Longevity, and Development of the Dialeurodes citri (Homoptera: Aleyrodidae) F1 Generation.

    PubMed

    Tariq, Kaleem; Noor, Mah; Saeed, Shafqat; Zhang, Hongyu

    2015-12-01

    Ultraviolet (UV) light has been used worldwide to monitor and trap insect pests. Whitefly adults show conspicuous positive phototactic behavior toward UV light stimuli; however, knowledge of the effect of UV light exposure on various life-history parameters of Dialeurodes citri remains limited. The present research aimed to investigate the effect of ultraviolet radiation (UV-A; long-wave) exposure on the reproduction and longevity of D. citri adults as well as the development of immature (eggs, larvae, and pupae) flies in the F1 generation. Paired D. citri adults were exposed to UV-A radiation for different periods (0, 1, 4, and 7 h/d) until the end of their life. The results of the experiment revealed that fecundity and oviposition rates increased when adults were irradiated for 1 and 4 h/d, but interestingly, both were significantly decreased compared with those of the controls after the longest exposure time (7 h/d). The longevity of adults of both sexes and the cumulative survival of F1 immatures were decreased with increased exposure time. Exposure to UV-A radiation prolonged the developmental time of immature stages, and a positive correlation was observed with exposure time. Exposure to UV light significantly inhibited egg hatching, larval development, pupation, and adult emergence. To the best of our knowledge, this is the first study describing the effect of UV radiation on a homopteran insect pest. This research may provide a foundation for the scientific community to use UV light in the field as an integrated pest management strategy to control this devastating agricultural pest.

  18. First report of citrus canker caused by Xanthomonas citri in Somalia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xanthomonas citri, causal agent of citrus canker, has been reported in several countries in Africa, but not Somalia. During 2006 and 2007, hyperplasia-type lesions, often surrounded by a water-soaked margin and yellow halo, typical of citrus canker caused by X. citri, were found on 8-10 year-old gr...

  19. Comparison of Droplet Digital PCR and Quantitative PCR Assays for Quantitative Detection of Xanthomonas citri Subsp. citri

    PubMed Central

    Yin, Youping; Wang, Zhongkang

    2016-01-01

    Droplet digital polymerase chain reaction (ddPCR) is a novel molecular biology technique providing absolute quantification of target nucleic acids without the need for an external calibrator. Despite its emerging applications in medical diagnosis, there are few reports of its use for the detection of plant pathogens. This work was designed to assess the diagnosis potential of the ddPCR for absolute quantitative detection of Xanthomonas citri subsp. citri, a quarantine plant pathogenic bacterium that causes citrus bacterial canker in susceptible Citrus species. We transferred an established quantitative PCR (qPCR) assay for citrus bacterial canker diagnosis directly to the ddPCR format and compared the performance of the two methods. The qPCR assay has a broader dynamic range compared to the ddPCR assay and the ddPCR assay has a significantly higher degree of sensitivity compared to the qPCR assay. The influence of PCR inhibitors can be reduced considerably in the ddPCR assay because the collection of end-point fluorescent signals and the counting of binomial events (positive or negative droplets) are associated with a Poisson algorithm. The ddPCR assay also shows lower coefficient of variation compared to the qPCR assay especially in low target concentration. The linear association of the measurements by ddPCR and qPCR assays is strong (Pearson correlation = 0.8633; P<0.001). Receiver operating characteristic analysis indicates the ddPCR methodology is a more robust approach for diagnosis of citrus bacterial canker. In summary, the results demonstrated that the ddPCR assay has the potential for the quantitative detection of X. citri subsp. citri with high precision and accuracy as compared with the results from qPCR assay. Further studies are required to evaluate and validate the value of ddPCR technology in the diagnosis of plant disease and quarantine applications. PMID:27427975

  20. Structural model and ligand interactions of the Xanthomonas axonopodis pv. citri oligopeptide-binding protein.

    PubMed

    Moutran, A; Balan, A; Ferreira, L C S; Giorgetti, A; Tramontano, A; Ferreira, R C C

    2007-12-11

    The oligopeptide-binding protein, OppA, ushers oligopeptide substrates to the membrane-associated oligopeptide permease (Opp), a multi-component ABC-type transporter involved in the uptake of oligopeptides by several bacterial species. In the present study, we report a structural model and an oligopeptide docking analysis of the OppA protein expressed by Xanthomonas axonopodis pv. citri (X. citri), the etiological agent of citrus canker. The X. citri OppA structural model showed a conserved three-dimensional structure, irrespective of the low amino acid identities with previously defined structures of Bacillus subtilis and Salmonella typhimurium orthologs. Oligopeptide docking analysis carried out with the proposed model indicated that the X. citri OppA preferentially binds tri- and tetrapeptides. The present study represents the first structural analysis of an OppA ortholog expressed by a phytopathogen and contributes to the understanding of the physiology and nutritional strategies of X. citri.

  1. Exposure to Diflubenzuron Results in an Up-Regulation of a Chitin Synthase 1 Gene in Citrus Red Mite, Panonychus citri (Acari: Tetranychidae)

    PubMed Central

    Xia, Wen-Kai; Ding, Tian-Bo; Niu, Jin-Zhi; Liao, Chong-Yu; Zhong, Rui; Yang, Wen-Jia; Liu, Bin; Dou, Wei; Wang, Jin-Jun

    2014-01-01

    Chitin synthase synthesizes chitin, which is critical for the arthropod exoskeleton. In this study, we cloned the cDNA sequences of a chitin synthase 1 gene, PcCHS1, in the citrus red mite, Panonychus citri (McGregor), which is one of the most economically important pests of citrus worldwide. The full-length cDNA of PcCHS1 contains an open reading frame of 4605 bp of nucleotides, which encodes a protein of 1535 amino acid residues with a predicted molecular mass of 175.0 kDa. A phylogenetic analysis showed that PcCHS1 was most closely related to CHS1 from Tetranychus urticae. During P. citri development, PcCHS1 was constantly expressed in all stages but highly expressed in the egg stage (114.8-fold higher than in the adult). When larvae were exposed to diflubenzuron (DFB) for 6 h, the mite had a significantly high mortality rate, and the mRNA expression levels of PcCHS1 were significantly enhanced. These results indicate a promising use of DFB to control P. citri, by possibly acting as an inhibitor in chitin synthesis as indicated by the up-regulation of PcCHS1 after exposure to DFB. PMID:24590130

  2. Identification of Xanthomonas citri ssp. citri host specificity genes in a heterologous expression host.

    PubMed

    Rybak, Myrian; Minsavage, Gerald V; Stall, Robert E; Jones, Jeffrey B

    2009-03-01

    We provide the first conclusive evidence that Xanthomonas axonopodis pv. citri Asiatic strain (Xac-A) and, in particular, Xac-A(w), a unique citrus canker A strain isolated from Key lime in Wellington, Florida, induces a hypersensitive reaction (HR) in grapefruit leaves. Using the heterologous tomato pathogen X. perforans, as a recipient of the Xac-A(w) genomic library, we identified a 1599-bp open reading frame responsible for HR in grapefruit, but not Key lime, and designated it avrGf1. Xac-A(w)DeltaavrGf1 produced typical, although visibly reduced, citrus canker symptoms (i.e. raised pustules) in grapefruit and typical canker symptoms in Key lime. We also determined that the X. perforans transconjugant carrying an Xac-A(w) hrpG elicited HR in grapefruit and Key lime leaves, and that xopA in X. perforans was partly responsible for HR. Xac-A transconjugants carrying the X. perforans xopA were reduced in ability to grow in grapefruit leaves relative to wild-type Xac-A. The X. perforans xopA appears to be a host-limiting factor. An avrBs3 homologue, which contained 18.5 repeats and induced HR in tomato, was designated avrTaw. This gene, when expressed in a pustule-minus Xac-A(w), did not complement pustule formation; however, pthA(w), a functional pthA homologue, complemented the mutant strain to produce typical pustules in Key lime, but markedly reduced pustules in grapefruit. Both avrBs3 homologues, when expressed in a typical Xac-A strain, resulted in typical citrus canker pustules in grapefruit, indicating that neither homologue suppressed pustule size in grapefruit. Xac-A(w) contains other unidentified factors that suppress development in grapefruit.

  3. Variations in type III effector repertoires, pathological phenotypes and host range of Xanthomonas citri pv. citri pathotypes.

    PubMed

    Escalon, Aline; Javegny, Stéphanie; Vernière, Christian; Noël, Laurent D; Vital, Karine; Poussier, Stéphane; Hajri, Ahmed; Boureau, Tristan; Pruvost, Olivier; Arlat, Matthieu; Gagnevin, Lionel

    2013-06-01

    The mechanisms determining the host range of Xanthomonas are still undeciphered, despite much interest in their potential roles in the evolution and emergence of plant pathogenic bacteria. Xanthomonas citri pv. citri (Xci) is an interesting model of host specialization because of its pathogenic variants: pathotype A strains infect a wide range of Rutaceous species, whereas pathotype A*/A(W) strains have a host range restricted to Mexican lime (Citrus aurantifolia) and alemow (Citrus macrophylla). Based on a collection of 55 strains representative of Xci worldwide diversity assessed by amplified fragment length polymorphism (AFLP), we investigated the distribution of type III effectors (T3Es) in relation to host range. We examined the presence of 66 T3Es from xanthomonads in Xci and identified a repertoire of 28 effectors, 26 of which were shared by all Xci strains, whereas two (xopAG and xopC1) were present only in some A*/A(W) strains. We found that xopAG (=avrGf1) was present in all A(W) strains, but also in three A* strains genetically distant from A(W) , and that all xopAG-containing strains induced the hypersensitive response (HR) on grapefruit and sweet orange. The analysis of xopAD and xopAG suggested horizontal transfer between X. citri pv. bilvae, another citrus pathogen, and some Xci strains. A strains were genetically less diverse, induced identical phenotypic responses and possessed indistinguishable T3E repertoires. Conversely, A*/A(W) strains exhibited a wider genetic diversity in which clades correlated with geographical origin and T3E repertoire, but not with pathogenicity, according to T3E deletion experiments. Our data outline the importance of taking into account the heterogeneity of Xci A*/A(W) strains when analysing the mechanisms of host specialization.

  4. Different Transcriptional Response to Xanthomonas citri subsp. citri between Kumquat and Sweet Orange with Contrasting Canker Tolerance

    PubMed Central

    Fu, Xing-Zheng; Gong, Xiao-Qing; Zhang, Yue-Xin; Wang, Yin; Liu, Ji-Hong

    2012-01-01

    Citrus canker disease caused by Xanthomonas citri subsp. citri (Xcc) is one of the most devastating biotic stresses affecting the citrus industry. Meiwa kumquat (Fortunella crassifolia) is canker-resistant, while Newhall navel orange (Citrus sinensis Osbeck) is canker-sensitive. To understand the molecular mechanisms underlying the differences in responses to Xcc, transcriptomic profiles of these two genotypes following Xcc attack were compared by using the Affymetrix citrus genome GeneChip. A total of 794 and 1324 differentially expressed genes (DEGs) were identified as canker-responsive genes in Meiwa and Newhall, respectively. Of these, 230 genes were expressed in common between both genotypes, while 564 and 1094 genes were only significantly expressed in either Meiwa or Newhall. Gene ontology (GO) annotation and Singular Enrichment Analysis (SEA) of the DEGs showed that genes related to the cell wall and polysaccharide metabolism were induced for basic defense in both Meiwa and Newhall, such as chitinase, glucanase and thaumatin-like protein. Moreover, apart from inducing basic defense, Meiwa showed specially upregulated expression of several genes involved in the response to biotic stimulus, defense response, and cation binding as comparing with Newhall. And in Newhall, abundant photosynthesis-related genes were significantly down-regulated, which may be in order to ensure the basic defense. This study revealed different molecular responses to canker disease in Meiwa and Newhall, affording insight into the response to canker and providing valuable information for the identification of potential genes for engineering canker tolerance in the future. PMID:22848606

  5. The role as inoculum sources of Xanthomonas citri pv. citri surviving on the infected Satsuma mandarin fruits.

    PubMed

    Kang, So Young; Kim, Ki Deok; Hong, Jeum Kyu; Hyun, He Nam; Jeun, Yong Chull

    2014-05-01

    Importing citrus fruits infected by Asiatic citrus canker caused by Xanthomonas citri pv. citri (Xcc) can act as an inoculum source for the disease epidemic in citrus canker-free countries. In this study, the pathogenicity of the causal agent of Asiatic citrus canker surviving on infected Satsuma mandarin fruits was evaluated. The washing solution of infected Satsuma mandarin fruits did not cause lesion formation on the citrus leaves. However, a typical citrus canker lesion was formed on the leaves after inoculation with higher concentrations of the inoculum from the washing solution (washing solution II). It indicated that the pathogenicity of the citrus canker surviving on the symptomatic Satsuma mandarin fruits was not changed. Scanning electron microscopic observation showed that the numbers of bacterial cells on the leaves of Satsuma mandarin which inoculated with the washing solution directly (washing solution I) was less compared to those of leaves inoculated with the washing solution II. This result spports that the pathogenicity of Xcc surviving on Satsuma mandarin fruits may not be changed but that the sucessful infection of citrus caker may depend on the concentration of the inoculum.

  6. Effect of X-irradiation on Citrus Canker Pathogen Xanthomonas citri subsp. citri of Satsuma Mandarin Fruits

    PubMed Central

    Song, Min-A; Park, Jae Sin; Kim, Ki Deok; Jeun, Yong Chull

    2015-01-01

    Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is one of the most important bacterial diseases of citrus. Because citrus canker is not found in many countries including European Union and Australia, Xcc is strictly regulated in order to prevent its spread. In this study, the effects of X-irradiation on Xcc growth either in the suspension or on the surface of citrus fruits were investigated. The suspension containing 1×107 cfu/ml of Xcc was irradiated with different absorbed doses of X-irradiation ranging from 50 to 400 Gy. The results showed that Xcc was fully dead at 400 Gy of X-irradiation. To determine the effect of X-irradiation on quarantine, the Xcc-inoculated citrus fruits were irradiated with different X-ray doses at which Xcc was completely inhibited by an irradiation dose of 250 Gy. The D10 value for Xcc on citrus fruits was found to be 97 Gy, indicating the possibility of direct application on citrus quarantine without any side sterilizer. Beside, presence of Xcc on the surface of asymptomatic citrus fruits obtained from citrus canker-infected orchards was noted. It indicated that the exporting citrus fruits need any treatment so that Xcc on the citrus fruits should be completely eliminated. Based on these results, ionizing radiation can be considered as an alternative method of eradicating Xcc for export of citrus fruits. PMID:26672670

  7. Presence of Extracellular DNA during Biofilm Formation by Xanthomonas citri subsp. citri Strains with Different Host Range

    PubMed Central

    Sena-Vélez, Marta; Redondo, Cristina; Graham, James H.; Cubero, Jaime

    2016-01-01

    Xanthomonas citri subsp. citri (Xcc) A strain causes citrus bacterial canker, a serious leaf, fruit and stem spotting disease of several Citrus species. X. alfalfae subsp. citrumelonis (Xac) is the cause of citrus bacterial spot, a minor disease of citrus nursery plants and X. campestris pv. campestris (Xc) is a systemic pathogen that causes black rot of cabbage. Xanthomonas spp. form biofilms in planta that facilitate the host infection process. Herein, the role of extracellular DNA (eDNA) was evaluated in the formation and stabilization of the biofilm matrix at different stages of biofilm development. Fluorescence and light microscopy, as well as DNAse treatments, were used to determine the presence of eDNA in biofilms and bacterial cultures. DNAse treatments of Xcc strains and Xac reduced biofilm formation at the initial stage of development, as well as disrupted preformed biofilm. By comparison, no significant effect of the DNAse was detected for biofilm formation by Xc. DNAse effects on biofilm formation or disruption varied among Xcc strains and Xanthomonas species which suggest different roles for eDNA. Variation in the structure of fibers containing eDNA in biofilms, bacterial cultures, and in twitching motility was also visualized by microscopy. The proposed roles for eDNA are as an adhesin in the early stages of biofilm formation, as an structural component of mature bacterial aggregates, and twitching motility structures. PMID:27248687

  8. Xanthomonas citri ssp. citri requires the outer membrane porin OprB for maximal virulence and biofilm formation.

    PubMed

    Ficarra, Florencia A; Grandellis, Carolina; Galván, Estela M; Ielpi, Luis; Feil, Regina; Lunn, John E; Gottig, Natalia; Ottado, Jorgelina

    2016-05-25

    Xanthomonas citri ssp. citri (Xcc) causes canker disease in citrus, and biofilm formation is critical for the disease cycle. OprB (Outer membrane protein B) has been shown previously to be more abundant in Xcc biofilms compared with the planktonic state. In this work, we showed that the loss of OprB in an oprB mutant abolishes bacterial biofilm formation and adherence to the host, and also compromises virulence and efficient epiphytic survival of the bacteria. Moreover, the oprB mutant is impaired in bacterial stress resistance. OprB belongs to a family of carbohydrate transport proteins, and the uptake of glucose is decreased in the mutant strain, indicating that OprB transports glucose. Loss of OprB leads to increased production of xanthan exopolysaccharide, and the carbohydrate intermediates of xanthan biosynthesis are also elevated in the mutant. The xanthan produced by the mutant has a higher viscosity and, unlike wild-type xanthan, completely lacks pyruvylation. Overall, these results suggest that Xcc reprogrammes its carbon metabolism when it senses a shortage of glucose input. The participation of OprB in the process of biofilm formation and virulence, as well as in metabolic changes to redirect the carbon flux, is discussed. Our results demonstrate the importance of environmental nutrient supply and glucose uptake via OprB for Xcc virulence.

  9. Expression profiling of virulence and pathogenicity genes of Xanthomonas axonopodis pv. citri.

    PubMed

    Astua-Monge, Gustavo; Freitas-Astua, Juliana; Bacocina, Gisele; Roncoletta, Juliana; Carvalho, Sérgio A; Machado, Marcos A

    2005-02-01

    DNA macroarrays of 279 genes of Xanthomonas axonopodis pv. citri potentially associated with pathogenicity and virulence were used to compare the transcriptional alterations of this bacterium in response to two synthetic media. Data analysis indicated that 31 genes were up-regulated by synthetic medium XVM2, while only 7 genes were repressed. The results suggest that XVM2 could be used as an in vitro system to identify candidate genes involved in pathogenesis of X. axonopodis pv. citri.

  10. Biofilm formation, epiphytic fitness, and canker development in Xanthomonas axonopodis pv. citri.

    PubMed

    Rigano, Luciano A; Siciliano, Florencia; Enrique, Ramón; Sendín, Lorena; Filippone, Paula; Torres, Pablo S; Qüesta, Julia; Dow, J Maxwell; Castagnaro, Atilio P; Vojnov, Adrián A; Marano, María Rosa

    2007-10-01

    The phytopathogenic bacterium Xanthomonas axonopodis pv. citri is responsible for the canker disease affecting citrus plants throughout the world. Here, we have evaluated the role of bacterial attachment and biofilm formation in leaf colonization during canker development on lemon leaves. Crystal violet staining and confocal laser scanning microscopy analysis of X. axonopodis pv. citri strains expressing the green fluorescent protein were used to evaluate attachment and biofilm formation on abiotic and biotic (leaf) surfaces. Wild-type X. axonopodis pv. citri attached to and formed a complex, structured biofilm on glass in minimal medium containing glucose. Similar attachment and structured biofilm formation also were seen on lemon leaves. An X. axonopodis pv. citri gumB mutant strain, defective in production of the extracellular polysaccharide xanthan, did not form a structured biofilm on either abiotic or biotic surfaces. In addition, the X. axonopodis pv. citri gumB showed reduced growth and survival on leaf surfaces and reduced disease symptoms. These findings suggest an important role for formation of biofilms in the epiphytic survival of X. axonopodis pv. citri prior to development of canker disease.

  11. Use of recombinant tobacco mosaic virus to achieve RNA interference in plants against the citrus mealybug, Planococcus citri (Hemiptera: Pseudococcidae).

    PubMed

    Khan, Arif Muhammad; Ashfaq, Muhammad; Kiss, Zsofia; Khan, Azhar Abbas; Mansoor, Shahid; Falk, Bryce W

    2013-01-01

    The citrus mealybug, Planococcus citri, is an important plant pest with a very broad plant host range. P. citri is a phloem feeder and loss of plant vigor and stunting are characteristic symptoms induced on a range of host plants, but P. citri also reduces fruit quality and causes fruit drop leading to significant yield reductions. Better strategies for managing this pest are greatly needed. RNA interference (RNAi) is an emerging tool for functional genomics studies and is being investigated as a practical tool for highly targeted insect control. Here we investigated whether RNAi effects can be induced in P. citri and whether candidate mRNAs could be identified as possible targets for RNAi-based P. citri control. RNAi effects were induced in P. citri, as demonstrated by specific target reductions of P. citri actin, chitin synthase 1 and V-ATPase mRNAs after injection of the corresponding specific double-stranded RNA inducers. We also used recombinant Tobacco mosaic virus (TMV) to express these RNAi effectors in Nicotiana benthamiana plants. We found that P. citri showed lower fecundity and pronounced death of crawlers after feeding on recombinant TMV-infected plants. Taken together, our data show that actin, chitin synthase 1 and V-ATPase mRNAs are potential targets for RNAi against P. citri, and that recombinant TMV is an effective tool for evaluating candidate RNAi effectors in plants.

  12. Comparative genomic and transcriptome analyses of pathotypes of Xanthomonas citri subsp. citri provide insights into mechanisms of bacterial virulence and host range

    PubMed Central

    2013-01-01

    Background Citrus bacterial canker is a disease that has severe economic impact on citrus industries worldwide and is caused by a few species and pathotypes of Xanthomonas. X. citri subsp. citri strain 306 (XccA306) is a type A (Asiatic) strain with a wide host range, whereas its variant X. citri subsp. citri strain Aw12879 (Xcaw12879, Wellington strain) is restricted to Mexican lime. Results To characterize the mechanism for the differences in host range of XccA and Xcaw, the genome of Xcaw12879 that was completed recently was compared with XccA306 genome. Effectors xopAF and avrGf1 are present in Xcaw12879, but were absent in XccA306. AvrGf1 was shown previously for Xcaw to cause hypersensitive response in Duncan grapefruit. Mutation analysis of xopAF indicates that the gene contributes to Xcaw growth in Mexican lime but does not contribute to the limited host range of Xcaw. RNA-Seq analysis was conducted to compare the expression profiles of Xcaw12879 and XccA306 in Nutrient Broth (NB) medium and XVM2 medium, which induces hrp gene expression. Two hundred ninety two and 281 genes showed differential expression in XVM2 compared to in NB for XccA306 and Xcaw12879, respectively. Twenty-five type 3 secretion system genes were up-regulated in XVM2 for both XccA and Xcaw. Among the 4,370 common genes of Xcaw12879 compared to XccA306, 603 genes in NB and 450 genes in XVM2 conditions were differentially regulated. Xcaw12879 showed higher protease activity than XccA306 whereas Xcaw12879 showed lower pectate lyase activity in comparison to XccA306. Conclusions Comparative genomic analysis of XccA306 and Xcaw12879 identified strain specific genes. Our study indicated that AvrGf1 contributes to the host range limitation of Xcaw12879 whereas XopAF contributes to virulence. Transcriptome analyses of XccA306 and Xcaw12879 presented insights into the expression of the two closely related strains of X. citri subsp. citri. Virulence genes including genes encoding T3SS components

  13. Molecular Characterization of Vitellogenin and Its Receptor Genes from Citrus Red Mite, Panonychus citri (McGregor)

    PubMed Central

    Zhong, Rui; Ding, Tian-Bo; Niu, Jin-Zhi; Xia, Wen-Kai; Liao, Chong-Yu; Dou, Wei; Wang, Jin-Jun

    2015-01-01

    The production and uptake of yolk protein play an important role in the reproduction of all oviparous organisms. Vitellogenin (Vg) is the precursor of vitellin (Vn), which is the major egg storage protein, and vitellogenin receptor (VgR) is a necessary protein for the uptake of Vg into developing oocytes. In this paper, we characterize the full-length Vg and VgR, PcVg1 and PcVgR, respectively, of the citrus red mite Panonychus citri (McGregor). The PcVg1 cDNA is 5748 nucleotides (nt) with a 5553-nt open reading frame (ORF) coding for 1851 amino acids (aa), and the PcVgR is 6090 nt, containing an intact ORF of 5673 nt coding an expected protein of 1891 aa. The PcVg1 aa sequence shows a typical GLCG domain and several K/RXXR cleavage sites, and PcVgR comprises two ligand-binding domains, two epidermal growth factor (EGF)-like regions containing YWTD motifs, a transmembrane domain, and a cytoplasmic domain. An analysis of the aa sequences and phylogenetics implied that both genes were genetically distinct from those of ticks and insects. The transcriptional profiles determined by real-time quantitative PCR in different developmental stages showed that both genes present the same expressional tendencies in eggs, larvae, nymphs, and adults. This suggested that the biosynthesis and uptake of PcVg occurs coordinately. The strong reproductive capacity of P. citri has been hypothesized as an important factor in its resistance; consequently, understanding the molecular mechanisms regulating Vg and VgR are fundamental for mite control. PMID:25739087

  14. Immune response and survival of Circulifer haematoceps to Spiroplasma citri infection requires expression of the gene hexamerin.

    PubMed

    Eliautout, Rémi; Dubrana, Marie-Pierre; Vincent-Monégat, Carole; Vallier, Agnès; Braquart-Varnier, Christine; Poirié, Marylène; Saillard, Colette; Heddi, Abdelaziz; Arricau-Bouvery, Nathalie

    2016-01-01

    Spiroplasma citri is a cell wall-less bacterium that infects plants. It is transmitted by the leafhopper Circulifer haematoceps, which hosts this bacterium in the haemocel and insect tissues. Bacterial factors involved in spiroplasma colonization of the insect host have been identified, but the immune response of the leafhopper to S. citri infection remains unknown. In this study, we showed that C. haematoceps activates both humoral and cellular immune responses when challenged with bacteria. When infected by S. citri, C. haematoceps displayed a specific immune response, evidenced by activation of phagocytosis and upregulation of a gene encoding the protein hexamerin. S. citri infection also resulted in decreased phenoloxidase-like activity. Inhibition of hexamerin by RNA interference resulted in a significant reduction in phenoloxidase-like activity and increased mortality of infected leafhoppers. Therefore, the gene hexamerin is involved in S. citri control by interfering with insect phenoloxidase activity.

  15. Identification of Immunity-Related Genes in Dialeurodes citri against Entomopathogenic Fungus Lecanicillium attenuatum by RNA-Seq Analysis

    PubMed Central

    Yu, Shijiang; Ding, Lili; Luo, Ren; Li, Xiaojiao; Yang, Juan; Liu, Haoqiang; Cong, Lin; Ran, Chun

    2016-01-01

    Dialeurodes citri is a major pest in citrus producing areas, and large-scale outbreaks have occurred increasingly often in recent years. Lecanicillium attenuatum is an important entomopathogenic fungus that can parasitize and kill D. citri. We separated the fungus from corpses of D. citri larvae. However, the sound immune defense system of pests makes infection by an entomopathogenic fungus difficult. Here we used RNA sequencing technology (RNA-Seq) to build a transcriptome database for D. citri and performed digital gene expression profiling to screen genes that act in the immune defense of D. citri larvae infected with a pathogenic fungus. De novo assembly generated 84,733 unigenes with mean length of 772 nt. All unigenes were searched against GO, Nr, Swiss-Prot, COG, and KEGG databases and a total of 28,190 (33.3%) unigenes were annotated. We identified 129 immunity-related unigenes in transcriptome database that were related to pattern recognition receptors, information transduction factors and response factors. From the digital gene expression profile, we identified 441 unigenes that were differentially expressed in D. citri infected with L. attenuatum. Through calculated Log2Ratio values, we identified genes for which fold changes in expression were obvious, including cuticle protein, vitellogenin, cathepsin, prophenoloxidase, clip-domain serine protease, lysozyme, and others. Subsequent quantitative real-time polymerase chain reaction analysis verified the results. The identified genes may serve as target genes for microbial control of D. citri. PMID:27644092

  16. XacFhaB adhesin, an important Xanthomonas citri ssp. citri virulence factor, is recognized as a pathogen-associated molecular pattern.

    PubMed

    Garavaglia, Betiana S; Zimaro, Tamara; Abriata, Luciano A; Ottado, Jorgelina; Gottig, Natalia

    2016-12-01

    Adhesion to host tissue is one of the key steps of the bacterial pathogenic process. Xanthomonas citri ssp. citri possesses a non-fimbrial adhesin protein, XacFhaB, required for bacterial attachment, which we have previously demonstrated to be an important virulence factor for the development of citrus canker. XacFhaB is a 4753-residue-long protein with a predicted β-helical fold structure, involved in bacterial aggregation, biofilm formation and adhesion to the host. In this work, to further characterize this protein and considering its large size, XacFhaB was dissected into three regions based on bioinformatic and structural analyses for functional studies. First, the capacity of these protein regions to aggregate bacterial cells was analysed. Two of these regions were able to form bacterial aggregates, with the most amino-terminal region being dispensable for this activity. Moreover, XacFhaB shows features resembling pathogen-associated molecular patterns (PAMPs), which are recognized by plants. As PAMPs activate plant basal immune responses, the role of the three XacFhaB regions as elicitors of these responses was investigated. All adhesin regions were able to induce basal immune responses in host and non-host plants, with a stronger activation by the carboxyl-terminal region. Furthermore, pre-infiltration of citrus leaves with XacFhaB regions impaired X. citri ssp. citri growth, confirming the induction of defence responses and restraint of citrus canker. This work reveals that adhesins from plant pathogens trigger plant defence responses, opening up new pathways for the development of protective strategies for disease control.

  17. The Amino Acid Arginine 210 of the Response Regulator HrpG of Xanthomonas citri subsp. citri Is Required for HrpG Function in Virulence.

    PubMed

    Ficarra, Florencia A; Garofalo, Cecilia G; Gottig, Natalia; Ottado, Jorgelina

    2015-01-01

    Xanthomonas citri subsp. citri colonizes its hosts through the trafficking of effector proteins to the plant cell by the type III protein secretion system. In X. citri subsp. citri, as in other plant pathogens, the hrp cluster encodes the type III protein secretion system and is regulated by the transcription factors HrpG and HrpX. HrpG belongs to the OmpR family's response regulator of EnvZ/OmpR two-component signal transduction system. Here, we show that the arginine 210 residue is crucial for the transcriptional activity of HrpG revealed by the absence of disease in host plants and hypersensitive response in non-host plants when a strain carrying this point mutation is used in plant infiltration assays. Also, this strain showed decreased expression levels of hrp genes in bacteria grown in culture or when they were recovered from citrus leaves. Moreover, we show for the first time that HrpG binds to both hrpX and its own promoter, and the change of the arginine 210 by a cysteine does not prevent the binding to both promoters. Nevertheless, in vitro hrpX transcription was observed only with HrpG whereas no transcription was detected with the R210C mutant. HrpG was able to interact with itself as well as with the mutant R210C suggesting that it functions as a dimer. The mutant protein R210C showed altered protease sensitivity, suggesting that Arg210 is essential for protein active conformation and thus for transcriptional activity. Our results indicate that arginine 210 in HrpG, as it may occur with this conserved residue in other members of this family of response regulators, is not required for DNA binding whereas is essential for hrp genes transcription and therefore for pathogenicity and HR induction.

  18. Insertion sequence- and tandem repeat-based genotyping techniques for Xanthomonas citri pv. mangiferaeindicae.

    PubMed

    Pruvost, O; Vernière, C; Vital, K; Guérin, F; Jouen, E; Chiroleu, F; Ah-You, N; Gagnevin, L

    2011-07-01

    Molecular fingerprinting techniques that have the potential to identify or subtype bacteria at the strain level are needed for improving diagnosis and understanding of the epidemiology of pathogens such as Xanthomonas citri pv. mangiferaeindicae, which causes mango bacterial canker disease. We developed a ligation-mediated polymerase chain reaction targeting the IS1595 insertion sequence as a means to differentiate pv. mangiferaeindicae from the closely related pv. anacardii (responsible for cashew bacterial spot), which has the potential to infect mango but not to cause significant disease. This technique produced weakly polymorphic fingerprints composed of ≈70 amplified fragments per strain for a worldwide collection of X. citri pv. mangiferaeindicae but produced no or very weak amplification for pv. anacardii strains. Together, 12 tandem repeat markers were able to subtype X. citri pv. mangiferaeindicae at the strain level, distinguishing 231 haplotypes from a worldwide collection of 299 strains. Multilocus variable number of tandem repeats analysis (MLVA), IS1595-ligation-mediated polymerase chain reaction, and amplified fragment length polymorphism showed differences in discriminatory power and were congruent in describing the diversity of this strain collection, suggesting low levels of recombination. The potential of the MLVA scheme for molecular epidemiology studies of X. citri pv. mangiferaeindicae is discussed.

  19. Reduced susceptibility to Xanthomonas citri in transgenic citrus expressing the FLS2 receptor from Nicotiana benthamiana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Overexpression of plant pattern-recognition receptors (PRRs) by genetic engineering provides a novel approach to enhance plant immunity and broad-spectrum disease resistance. The citrus canker disease associated with Xanthomonas citri is one of the important diseases damaging citrus production world...

  20. Molecular Detection of Spiroplasma Citri Associated with Stubborn Disease in Citrus Orchards in Syria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spiroplasma citri, a phloem-limited pathogen, causes citrus stubborn disease (CSD) and can be transmitted from plant to plant by several species of phloem-feeding leafhoppers. CSD is an important disorder in certain warm and arid citrus-growing areas, and its agent has been recorded from several Med...

  1. HrpG and HrpX play global roles in coordinating different virulence traits of Xanthomonas axonopodis pv. citri.

    PubMed

    Guo, Yinping; Figueiredo, Francisco; Jones, Jeffery; Wang, Nian

    2011-06-01

    Xanthomonas axonopodis pv. citri is the causal agent of citrus canker, which is one of the most serious diseases of citrus. To understand the virulence mechanisms of X. axonopodis pv. citri, we designed and conducted genome-wide microarray analyses to characterize the HrpG and HrpX regulons, which are critical for the pathogenicity of X. axonopodis pv. citri. Our analyses revealed that 232 and 181 genes belonged to the HrpG and HrpX regulons, respectively. In total, 123 genes were overlapped in the two regulons at any of the three selected timepoints representing three growth stages of X. axonopodis pv. citri in XVM2 medium. Our results showed that HrpG and HrpX regulated all 24 type III secretion system genes, 23 type III secretion system effector genes, and 29 type II secretion system substrate genes. Our data revealed that X. axonopodis pv. citri regulates multiple cellular activities responding to the host environment, such as amino acid biosynthesis; oxidative phosphorylation; pentose-phosphate pathway; transport of sugar, iron, and potassium; and phenolic catabolism, through HrpX and HrpG. We found that 124 and 90 unknown genes were controlled by HrpG and HrpX, respectively. Our results suggest that HrpG and HrpX interplay with a global signaling network and co-ordinate the expression of multiple virulence factors for modification and adaption of host environment during X. axonopodis pv. citri infection.

  2. Gene response to stress in the Asian citrus psyllid (Hemiptera: Psyllidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transcriptional responses of the Asian citrus psyllid, Diaphorina citri, under three stress factors were investigated: physical wounding, heat stress, and exposure to low doses of the insecticide imidacloprid. The Asian citrus psyllid, Diaphorina citri, is a vector of the phloem-inhabiting bacterium...

  3. The relevance of Murraya paniculata and related species as potential hosts and inoculum reservoirs of Candidatus Liberibacter asiaticus, causal agent of Huanglongbing (HLB)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB), considered the most serious insect-vectored bacterial disease of citrus, is transmitted in nature by the Asian citrus psyllid Diaphorina citri and the African citrus psyllid Trioza erytreae. Diaphorina citri was discovered in southern Florida in 1998 and the HLB disease in 2005...

  4. Formic and acetic acids in degradation products of plant volatiles elicit olfactory and behavorial responses from an insect vector

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) vectors the bacterial pathogen presumed to be the etiological agent of citrus greening disease, Huanglongbing (HLB), a major threat to citrus industry worldwide. We studied antennal and behavioral responses of Diaphorina citri...

  5. Plant lectin-like antibacterial proteins from phytopathogens Pseudomonas syringae and Xanthomonas citri.

    PubMed

    Ghequire, Maarten G K; Li, Wen; Proost, Paul; Loris, Remy; De Mot, René

    2012-08-01

    The genomes of Pseudomonas syringae pv. syringae 642 and Xanthomonas citri pv. malvacearum LMG 761 each carry a putative homologue of the plant lectin-like bacteriocin (llpA) genes previously identified in the rhizosphere isolate Pseudomonas putida BW11M1 and the biocontrol strain Pseudomonas fluorescens Pf-5. The respective purified recombinant proteins, LlpAPss642 and LlpAXcm761 , display genus-specific antibacterial activity across species boundaries. The inhibitory spectrum of the P. syringae bacteriocin overlaps partially with those of the P. putida and P. fluorescens LlpAs. Notably, Xanthomonas axonopodis pv. citri str. 306 secretes a protein identical to LlpAXcm761 . The functional characterization of LlpA proteins from two different phytopathogenic γ-proteobacterial species expands the lectin-like bacteriocin family beyond the Pseudomonas genus and suggests its involvement in competition among closely related plant-associated bacteria with different lifestyles.

  6. A simple method for in vivo expression studies of Xanthomonas axonopodis pv. citri.

    PubMed

    Mehta, Angela; Rosato, Yoko B

    2003-11-01

    A major problem in studying bacterial plant pathogens is obtaining the microorganism directly from the plant tissue to perform in vivo expression (protein or mRNA) analyses. Here we report an easy and fast protocol to isolate Xanthomonas axonopodis pv. citri directly from the host plant, in sufficient amounts to perform protein fingerprinting by 2-D gel electrophoresis as well as RNA expression assays. The protein profile obtained was very similar to that of X. axonopodis pv. citri grown in the presence of a leaf extract of Citrus sinensis; however, some differential proteins expressed in vivo were observed. Total RNA extraction revealed typical 16S and 23S bands in the agarose gel, and RT-PCR reactions using primers specific for genes of the bacterium confirmed the quality of the RNA preparation. Also, RT-PCR reactions using plant ribosomal primers were employed, and no amplification product was obtained, indicating that plant RNA is not present in the bacterium RNA sample.

  7. Adjuvants to improve aerial control of the citrus mealybug Planococcus citri (Hemiptera: Pseudococcidae) using entomopathogenic nematodes.

    PubMed

    van Niekerk, S; Malan, A P

    2015-03-01

    The citrus mealybug, Planococcus citri, is a highly destructive pest of citrus, occurring only in the aerial parts of plants. Humidity will be one of the key factors to consider when using entomopathogenic nematodes (EPN) as biological control agents. Different adjuvants can be added to suspensions of EPNs, to improve control as a foliar application. An aqueous suspension containing Heterorhabditis zealandica and 0.3% Zeba® significantly increased P. citri mortality by 22% at 80% relative humidity (RH) with a temperature cycle starting at 22°C for 14 h and 11°C for 11 h. The same polymer formulation was tested for Steinernema yirgalemense and mortality of P. citri increased by 21% at 60% RH and by 27% at 80% RH. The addition of Nu-Film-P® and Zeba® to H. zealandica suspensions did not significantly retard application run-off on citrus leaves. The combination of Nu-Film-P® and Zeba®, however, was able to significantly retard sedimentation, increasing the average number of nematodes deposited on 2-cm2 leaf discs by 10 nematodes. In an aqueous suspension, nematodes settle rapidly to the bottom, resulting in an uneven distribution of nematodes. Xanthan gum, at a concentration of 0.2%, was highly effective at retarding sedimentation, with 72% of the initial nematode number still in suspension after 1 h. Zeba®, at a concentration of 0.3%, despite not being as effective as Xanthan gum, nevertheless still retarded sedimentation significantly. This is the first report of the potential of Nu-Film-P® and Zeba® to improve EPN performance against P. citri when used above ground in citrus orchards.

  8. Analyses of binding sequences of the two LexA proteins of Xanthomonas axonopodis pathovar citri.

    PubMed

    Yang, Mei-Kwei; Hsu, Chien-Hsiu; Sung, Vin-Long

    2008-07-01

    Xanthomonas axonopodis pv. citri (X. axonopodis pv. citri) possesses two lexA genes, designated lexA1 and lexA2. Electrophoretic mobility shift data show that LexA1 binds to both lexA1 and lexA2 promoters, but LexA2 does not bind to the lexA1 promoter, suggesting that LexA1 and LexA2 play different roles in regulating the expression of SOS genes. In this study, we have determined that LexA2 binds to a 14-bp dyad-spacer-dyad palindromic sequence, 5'-TGTACAAATGTACA-3', located at nucleotides -41 to -28 relative to the translation start site of lexA2 of X. axonopodis pv. citri. The two spacer nucleotides in this sequence can be changed from AA to TT without affecting LexA2 binding; all other base deletions or substitutions abolish LexA2 binding. The LexA1 binding sequence in the promoter region of lexA2 is TTAGTACTAAAGTTATAA and is located at -133 to -116, and that in the lexA1 gene is AGTAGTAATACTACT located at nucleotides -19 to -5 relative to the translation start site of lexA1. Any base change in the latter sequence abolishes LexA1 binding.

  9. The molybdate-binding protein (ModA) of the plant pathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Balan, Andrea; Santacruz, Carolina P; Moutran, Alexandre; Ferreira, Rita C C; Medrano, Francisco J; Pérez, Carlos A; Ramos, Carlos H I; Ferreira, Luís C S

    2006-12-01

    The modABC operon of phytopathogen Xanthomonas axonopodis pv. citri (X. citri) encodes a putative ABC transporter involved in the uptake of the molybdate and tungstate anions. Sequence analyses showed high similarity values of ModA orthologs found in X. campestris pv. campestris (X. campestris) and Escherichia coli. The X. citri modA gene was cloned in pET28a and the recombinant protein, expressed in the E. coli BL21 (DE3) strain, purified by immobilized metal affinity chromatography. The purified protein remained soluble and specifically bound molybdate and tungstate with K(d) 0.29+/-0.12 microM and 0.58+/-0.14 microM, respectively. Additionally binding of molybdate drastically enhanced the thermal stability of the recombinant ModA as compared to the apoprotein. This is the first characterization of a ModA ortholog expressed by a phytopathogen and represents an important tool for functional, biochemical and structural analyses of molybdate transport in Xanthomonas species.

  10. Deletion of pilA, a Minor Pilin-Like Gene, from Xanthomonas citri subsp. citri Influences Bacterial Physiology and Pathogenesis.

    PubMed

    Petrocelli, Silvana; Arana, Maite R; Cabrini, Marcela N; Casabuono, Adriana C; Moyano, Laura; Beltramino, Matías; Moreira, Leandro M; Couto, Alicia S; Orellano, Elena G

    2016-12-01

    Type IV pili (Tfp) are widely distributed adhesins of bacterial surfaces. In plant pathogenic bacteria, Tfp are involved in host colonization and pathogenesis. Xanthomonas citri subsp. citri (Xcc) is the phytopathogen responsible for citrus canker disease. In this work, three Tfp structural genes, fimA, fimA1, and pilA from Xcc were studied. A pilA mutant strain from Xcc (XccΔpilA) was constructed and differences in physiological features, such as motilities, adhesion, and biofilm formation, were observed. A structural study of the purified Tfp fractions from Xcc wild-type and Xcc∆pilA showed that pilins are glycosylated in both strains and that FimA and FimA1 are the main structural components of the pili. Furthermore, smaller lesion symptoms and reduced bacterial growth were produced by Xcc∆pilA in orange plants compared to the wild-type strain. These results indicate that the minor pilin-like gene, pilA, is involved in Tfp performance during the infection process.

  11. Bridgehead invasion of a monomorphic plant pathogenic bacterium: Xanthomonas citri pv. citri, an emerging citrus pathogen in Mali and Burkina Faso.

    PubMed

    Leduc, A; Traoré, Y N; Boyer, K; Magne, M; Grygiel, P; Juhasz, C C; Boyer, C; Guerin, F; Wonni, I; Ouedraogo, L; Vernière, C; Ravigné, V; Pruvost, O

    2015-11-01

    Molecular epidemiology studies further our understanding of migrations of phytopathogenic bacteria, the major determining factor in their emergence. Asiatic citrus canker, caused by Xanthomonas citri pv. citri, was recently reported in Mali and Burkina Faso, a region remote from other contaminated areas. To identify the origin and pathways of these emergences, we used two sets of markers, minisatellites and microsatellites, for investigating different evolutionary scales. Minisatellite typing suggested the introduction of two groups of strains in Mali (DAPC 1 and DAPC 2), consistent with microsatellite typing. DAPC 2 was restricted to Bamako district, whereas DAPC 1 strains were found much more invasive. The latter strains formed a major clonal complex based on microsatellite data with the primary and secondary founders detected in commercial citrus nurseries and orchards. This suggests that human activities played a major role in the spread of DAPC 1 strains via the movement of contaminated propagative material, further supported by the frequent lack of differentiation between populations from geographically distant nurseries and orchards. Approximate Bayesian Computation analyses supported the hypothesis that strains from Burkina Faso resulted from a bridgehead invasion from Mali. Multi-locus variable number of tandem repeat analysis and Approximate Bayesian Computation are useful for understanding invasion routes and pathways of monomorphic bacterial pathogens.

  12. Xanthomonas citri subsp. citri surface proteome by 2D-DIGE: Ferric enterobactin receptor and other outer membrane proteins potentially involved in citric host interaction.

    PubMed

    Carnielli, Carolina Moretto; Artier, Juliana; de Oliveira, Julio Cezar Franco; Novo-Mansur, Maria Teresa Marques

    2017-01-16

    Xanthomonas citri subsp. citri (XAC) is the causative agent of citrus canker, a disease of great economic impact around the world. Understanding the role of proteins on XAC cellular surface can provide new insights on pathogen-plant interaction. Surface proteome was performed in XAC grown in vivo (infectious) and in vitro (non-infectious) conditions, by labeling intact cells followed by cellular lysis and direct 2D-DIGE analysis. Seventy-nine differential spots were analyzed by mass spectrometry. Highest relative abundance for in vivo condition was observed for spots containing DnaK protein, 60kDa chaperonin, conserved hypothetical proteins, malate dehydrogenase, phosphomannose isomerase, and ferric enterobactin receptors. Elongation factor Tu, OmpA-related proteins, Oar proteins and some Ton-B dependent receptors were found in spots decreased in vivo. Some proteins identified on XAC's surface in infectious condition and predicted to be cytoplasmic, such as DnaK and 60KDa chaperonin, have also been previously found at cellular surface in other microorganisms. This is the first study on XAC surface proteome and results point to mediation of molecular chaperones in XAC-citrus interaction. The approach utilized here can be applied to other pathogen-host interaction systems and help to achieve new insights in bacterial pathogenicity toward promising targets of biotechnological interest.

  13. XbmR, a new transcription factor involved in the regulation of chemotaxis, biofilm formation and virulence in Xanthomonas citri subsp. citri.

    PubMed

    Yaryura, Pablo M; Conforte, Valeria P; Malamud, Florencia; Roeschlin, Roxana; de Pino, Verónica; Castagnaro, Atilio P; McCarthy, Yvonne; Dow, J Maxwell; Marano, María R; Vojnov, Adrián A

    2015-11-01

    Xanthomonas citri subsp. citri (Xcc) is the causal agent of citrus canker. Biofilm formation on citrus leaves plays an important role in epiphytic survival of Xcc. Biofilm formation is affected by transposon insertion in XAC3733, which encodes a transcriptional activator of the NtrC family, not linked to a gene encoding a sensor protein, thus could be considered as an 'orphan' regulator whose function is poorly understood in Xanthomonas spp. Here we show that mutation of XAC3733 (named xbmR) resulted in impaired structural development of the Xcc biofilm, loss of chemotaxis and reduced virulence in grapefruit plants. All defective phenotypes were restored to wild-type levels by the introduction of PA2567 from Pseudomonas aeruginosa, which encodes a phosphodiesterase active in the degradation of cyclic diguanosine monophosphate (c-di-GMP). A knockout of xbmR led to a substantial downregulation of fliA that encodes a σ(28) transcription factor, as well as fliC and XAC0350 which are potential member of the σ(28) regulon. XAC0350 encodes an HD-GYP domain c-di-GMP phosphodiesterase. These findings suggest that XbmR is a key regulator of flagellar-dependent motility and chemotaxis exerting its action through a regulatory pathway that involves FliA and c-di-GMP.

  14. The Arabidopsis Elongator complex is required for nonhost resistance against the bacterial pathogens Xanthomonas citri subsp. citri and Pseudomonas syringae pv. phaseolicola NPS3121.

    PubMed

    An, Chuanfu; Wang, Chenggang; Mou, Zhonglin

    2017-01-30

    Although in recent years nonhost resistance has attracted considerable attention for its broad spectrum and durability, the genetic and mechanistic components of nonhost resistance have not been fully understood. We used molecular and histochemical approaches including quantitative PCR, chromatin immunoprecipitation, and 3,3'-diaminobenzidine and aniline blue staining. The evolutionarily conserved histone acetyltransferase complex Elongator was identified as a major component of nonhost resistance against Xanthomonas citri subsp. citri (Xcc) and Pseudomonas syringae pv. phaseolicola (Psp) NPS3121. Mutations in Elongator genes inhibit Xcc-, Psp NPS3121- and/or flg22-induced defense responses including defense gene expression, callose deposition, and reactive oxygen species (ROS) and salicylic acid (SA) accumulation. Mutations in Elongator also attenuate the ROS-SA amplification loop. We show that suppressed ROS and SA accumulation in Elongator mutants is correlated with reduced expression of the Arabidopsis respiratory burst oxidase homologue AtrbohD and the SA biosynthesis gene ISOCHORISMATE SYNTHASE1 (ICS1). Furthermore, we found that the Elongator subunit ELP2 is associated with the chromatin of AtrbohD and ICS1 and is required for maintaining basal histone H3 acetylation levels in these key defense genes. As both AtrbohD and ICS1 contribute to nonhost resistance against Xcc, our results reveal an epigenetic mechanism by which Elongator regulates nonhost resistance in Arabidopsis.

  15. Identification and characterization of two uvrA genes of Xanthomonas axonopodis pathovar citri.

    PubMed

    Shen, Che-Hung; Chiang, Ying-Chieh; Hsu, Chien-Hsiu; Yang, Mei-Kwei

    2007-02-01

    Two uvrA-like genes, designated uvrA1 and uvrA2, that may be involved in nucleotide excision repair in Xanthomonas axonopodis pv. citri (X. a. pv. citri) strain XW47 were characterized. The uvrA1 gene was found to be 2,964 bp in length capable of encoding a protein of 987 amino acids. The uvrA2 gene was determined to be 2,529 bp with a coding potential of 842 amino acids. These two proteins share 71 and 39% identity, respectively, in amino acid sequence with the UvrA protein of Escherichia coli. Analyses of the deduced amino acid sequence revealed that UvrA1 and UvrA2 have structures characteristic of UvrA proteins, including the Walker A and Walker B motifs, zinc finger DNA binding domains, and helix-turn-helix motif with a polyglycine hinge region. The uvrA1 or uvrA2 mutant, constructed by gene replacement, was more sensitive to DNA-damaging agents methylmethane sulfonate (MMS), mitomycin C (MMC), or ultraviolet (UV) than the wild type. The uvrA1 mutant was four orders of magnitude more sensitive to UV irradiation and two orders of magnitude more sensitive to MMS than the uvrA2 mutant. The uvrA1uvrA2 double mutant was one order of magnitude more sensitive to MMS, MMC, or UV than the uvrA1 single mutant. These results suggest that UvrA1 plays a more important role than UvrA2 in DNA repair in X. a. pv. citri. Both uvrA1 and uvrA2 genes were found to be constitutively expressed in the wild type and lexA1 or lexA2 mutant of X. a. pv. citri, and treatment of these cells with sublethal dose of MMC did not alter the expression of these two genes. Results of electrophoresis mobility shift assays revealed that LexA1 or LexA2 does not bind to either the uvrA1 or the uvrA2 promoter. These results suggest that uvrA expression in X. a. pv. citri is not regulated by the SOS response system.

  16. Stubborn Disease in Iran: Diversity of Spiroplasma citri Strains in Circulifer haematoceps Leafhoppers Collected in Sesame Fields in Fars Province.

    PubMed

    Zarei, Zahra; Salehi, Mohammad; Azami, Zabihallah; Salari, Khadijeh; Béven, Laure

    2017-02-01

    Spiroplasma citri is a bacterial pathogen responsible for the economically important citrus stubborn disease. Sesame and citrus seeds serve as hosts for both S. citri and its leafhopper vector Circulifer haematoceps. To evaluate whether sesame could act as a reservoir for citrus-infecting strains or not, the genetic diversity among S. citri strains found in leafhoppers collected in citrus and citrus-free sesame fields was investigated. Among 26 periwinkle plants exposed to the collected C. haematoceps leafhoppers, 12 plants developed typical stubborn symptoms. All symptomatic periwinkles were polymerase chain reaction positive using S. citri-specific primer pairs targeting the spiralin and P89 genes. Phylogenetic trees based on spiralin gene sequence analysis indicated that the novel field-collected strains clustered with those belonging to two formerly defined S. citri groups (groups 6 and 1). In addition, our results strongly suggest that group 1 strains could be transmitted from sesame-infected plants to citrus trees by C. haematoceps, while group 6 strains may not infect citrus trees.

  17. Expression Patterns of Genes Involved in the Defense and Stress Response of Spiroplasma citri Infected Madagascar Periwinkle Catharanthus roseus

    PubMed Central

    Nejat, Naghmeh; Vadamalai, Ganesan; Dickinson, Matthew

    2012-01-01

    Madagascar periwinkle is an ornamental and a medicinal plant, and is also an indicator plant that is highly susceptible to phytoplasma and spiroplasma infections from different crops. Periwinkle lethal yellows, caused by Spiroplasma citri, is one of the most devastating diseases of periwinkle. The response of plants to S. citri infection is very little known at the transcriptome level. In this study, quantitative real-time PCR (RT-qPCR) was used to investigate the expression levels of four selected genes involved in defense and stress responses in naturally and experimentally Spiroplasma citri infected periwinkles. Strictosidine β-glucosidase involved in terpenoid indole alkaloids (TIAs) biosynthesis pathway showed significant upregulation in experimentally and naturally infected periwinkles. The transcript level of extensin increased in leaves of periwinkles experimentally infected by S. citri in comparison to healthy ones. A similar level of heat shock protein 90 and metallothionein expression was observed in healthy, naturally and experimentally spiroplasma-diseased periwinkles. Overexpression of Strictosidine β-glucosidase demonstrates the potential utility of this gene as a host biomarker to increase the fidelity of S. citri detection and can also be used in breeding programs to develop stable disease-resistance varieties. PMID:22408455

  18. Requirement of the galU Gene for Polysaccharide Production by and Pathogenicity and Growth In Planta of Xanthomonas citri subsp. citri▿

    PubMed Central

    Guo, Yinping; Sagaram, Uma Shankar; Kim, Jeong-soon; Wang, Nian

    2010-01-01

    Xanthomonas citri subsp. citri is the causal agent of citrus canker, which has a significant impact on citrus production. In this study, we characterized the galU gene of X. citri subsp. citri. Two galU mutants (F6 and D12) were identified in an X. citri subsp. citri EZ-Tn5 Tnp transposon library. Rescue cloning, sequence analysis, and Southern blot analysis indicated that both of these mutants had a single copy of the EZ-Tn5 transposon inserted in galU in the chromosome. Further study showed that galU was required for biosynthesis of extracellular polysaccharides (EPS; xanthan gum) and capsular polysaccharide (CPS) and biofilm formation. Mutation of galU resulted in a loss of pathogenicity for grapefruit. The loss of pathogenicity of a galU mutant resulted from its inability to grow in planta rather than from the effect on virulence genes. Quantitative reverse transcription-PCR assays indicated that mutation of galU did not impair the expression of key virulence genes, such as pthA of X. citri subsp. citri. Although D12 had a growth rate similar to that of the wild-type strain in nutrient broth, no D12 population became established in the intercellular spaces of citrus leaves. Coinoculation of a galU mutant with the wild-type strain did not promote growth of the galU mutant in planta. Defects in EPS and CPS production, pathogenicity, and growth in planta of the galU mutant were complemented to the wild-type level using plasmid pCGU2.1 containing an intact galU gene. These data indicate that the galU gene contributes to X. citri subsp. citri growth in intercellular spaces and is involved in EPS and CPS synthesis and biofilm formation. PMID:20118360

  19. Evaluation of efficacy of 18 strains of entomopathogenic nematodes (Rhabditida) against Planococcus citri (Risso, 1813) (Hemiptera: Pseudococcidae) under laboratory conditions.

    PubMed

    Barbosa Negrisoli, Carla Ruth de Carvalho; Negrisoli Júnior, Aldomario Santo; Botton, Marcos; Garcia, Mauro Silveira; Bernardi, Daniel

    2013-07-01

    Planococcus citri (Risso, 1813) (Hemiptera: Pseudococcidae) is an important plant virus vector in grapevine crops in Brazil and other countries. The mealybug grows in roots and leaves of the grapes. Entomopathogenic nematodes (EPNs) are efficient control agents against insects associated to the soil and could be applied with the same equipment used for chemical insecticides. The aim of this study was to select effective EPNs for controlling P. citri females in laboratory conditions (25±1°C, UR 60±10%). We tested 17 native [Steinernema rarum (6 strains), Steinernema glaseri, Steinernema feltiae, Steinernema riobrave, Steinernema sp., Heterorhabditis bacteriophora (7 strains)] and only one exotic strain (Steinernema carpocapsae ALL). The bioassays were done on Petri dishes infested with females of P. citri, which were sprayed with EPNs juveniles. The strain with larger pathogenicity and virulence in laboratory was H. bacteriophora RS33 (from 69.0% to 92.2% of mortality), native of Rio Grande do Sul.

  20. Production of the refolded oligopeptide-binding protein (OppA) encoded by the citrus pathogen Xanthomonas axonopodis pv. Citri.

    PubMed

    Balan, A; Ferreira, R C C; Ferreira, L C S

    2008-02-01

    The oligopeptide-binding protein, OppA, binds and ushers oligopeptide substrates to the membrane-associated oligopeptide permease (Opp), a multi-component ABC-type transporter involved in the uptake of oligopeptides expressed by several bacterial species. In the present study, we report the cloning, purification, refolding and conformational analysis of a recombinant OppA protein derived from Xanthomonas axonopodis pv. citri (X. citri), the etiological agent of citrus canker. The oppA gene was expressed in Escherichia coli BL21 (DE3) strain under optimized inducing conditions and the recombinant protein remained largely insoluble. Solubilization was achieved following refolding of the denatured protein. Circular dichroism analysis indicated that the recombinant OppA protein preserved conformational features of orthologs expressed by other bacterial species. The refolded recombinant OppA represents a useful tool for structural and functional analyses of the X. citri protein.

  1. Survival of Xanthomonas axonopodis pv. citri in Leaf Lesions Under Tropical Environmental Conditions and Simulated Splash Dispersal of Inoculum.

    PubMed

    Pruvost, O; Boher, B; Brocherieux, C; Nicole, M; Chiroleu, F

    2002-04-01

    ABSTRACT Asiatic citrus canker (ACC) is a severe disease of several citrus species and hybrids in many tropical and subtropical areas. Populations of Xanthomonas axonopodis pv. citri in leaf and twig lesions are the most important inoculum source for secondary infections. In areas with a marked winter season (e.g., Argentina and Japan), low temperatures induce a decrease of 10(2) to 10(4) in population sizes in lesions, thus creating a discontinuity in the X. axonopodis pv. citri life cycle. The purpose of this study was to evaluate the dynamics of X. axonopodis pv. citri populations in leaf lesions exposed to the mild winter temperatures prevailing in a tropical environment. Internal X. axonopodis pv. citri population levels in Mexican lime leaf lesions reached 10(6) to 10(7) CFU lesion(-1) whatever the lesion size. These densities, however, were not strongly negatively affected by winter temperatures prevailing under experimental conditions. The estimated decrease in internal X. axonopodis pv. citri population sizes was approximately 10-fold. When exposed to 35 mm h(-1) of simulated rainfall, internal population sizes decreased over time by approximately 1 log unit for lesions 1 and 2 months old, but did not for older lesions. A microscopic examination indicated that lignin-like compounds are present in lesions more than 6 months old. The slow decrease over time of X. axonopodis pv. citri population sizes in leaf lesions may be the balanced result of defense reactions by the host at late stages of disease development, and the concomitant multiplication of the pathogen at the margin of old lesions. We conclude that the epidemiological significance of overwintered leaf lesions in the tropics is higher than that reported in other areas.

  2. Structural and Physiological Analyses of the Alkanesulphonate-Binding Protein (SsuA) of the Citrus Pathogen Xanthomonas citri

    PubMed Central

    Tófoli de Araújo, Fabiano; Bolanos-Garcia, Victor M.; Pereira, Cristiane T.; Sanches, Mario; Oshiro, Elisa E.; Ferreira, Rita C. C.; Chigardze, Dimitri Y.; Barbosa, João Alexandre Gonçalves; de Souza Ferreira, Luís Carlos; Benedetti, Celso E.; Blundell, Tom L.; Balan, Andrea

    2013-01-01

    Background The uptake of sulphur-containing compounds plays a pivotal role in the physiology of bacteria that live in aerobic soils where organosulfur compounds such as sulphonates and sulphate esters represent more than 95% of the available sulphur. Until now, no information has been available on the uptake of sulphonates by bacterial plant pathogens, particularly those of the Xanthomonas genus, which encompasses several pathogenic species. In the present study, we characterised the alkanesulphonate uptake system (Ssu) of Xanthomonas axonopodis pv. citri 306 strain (X. citri), the etiological agent of citrus canker. Methodology/Principal Findings A single operon-like gene cluster (ssuEDACB) that encodes both the sulphur uptake system and enzymes involved in desulphurisation was detected in the genomes of X. citri and of the closely related species. We characterised X. citri SsuA protein, a periplasmic alkanesulphonate-binding protein that, together with SsuC and SsuB, defines the alkanesulphonate uptake system. The crystal structure of SsuA bound to MOPS, MES and HEPES, which is herein described for the first time, provides evidence for the importance of a conserved dipole in sulphate group coordination, identifies specific amino acids interacting with the sulphate group and shows the presence of a rather large binding pocket that explains the rather wide range of molecules recognised by the protein. Isolation of an isogenic ssuA-knockout derivative of the X. citri 306 strain showed that disruption of alkanesulphonate uptake affects both xanthan gum production and generation of canker lesions in sweet orange leaves. Conclusions/Significance The present study unravels unique structural and functional features of the X. citri SsuA protein and provides the first experimental evidence that an ABC uptake system affects the virulence of this phytopathogen. PMID:24282519

  3. Crystal structure of the FAD-containing ferredoxin-NADP+ reductase from the plant pathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Tondo, María Laura; Hurtado-Guerrero, Ramon; Ceccarelli, Eduardo A; Medina, Milagros; Orellano, Elena G; Martínez-Júlvez, Marta

    2013-01-01

    We have solved the structure of ferredoxin-NADP(H) reductase, FPR, from the plant pathogen Xanthomonas axonopodis pv. citri, responsible for citrus canker, at a resolution of 1.5 Å. This structure reveals differences in the mobility of specific loops when compared to other FPRs, probably unrelated to the hydride transfer process, which contributes to explaining the structural and functional divergence between the subclass I FPRs. Interactions of the C-terminus of the enzyme with the phosphoadenosine of the cofactor FAD limit its mobility, thus affecting the entrance of nicotinamide into the active site. This structure opens the possibility of rationally designing drugs against the X. axonopodis pv. citri phytopathogen.

  4. Protective Effect against Hydroxyl-induced DNA Damage and Antioxidant Activity of Citri reticulatae Pericarpium

    PubMed Central

    Li, Xican; Huang, Yanping; Chen, Dongfeng

    2013-01-01

    Purpose: As a typical Chinese herbal medicine, Citri reticulatae pericarpium (CRP) possesses various pharmacological effects involved in antioxidant ability. However, its antioxidant effects have not been reported yet. The objective of this work was to investigate its antioxidant ability, then further discuss the antioxidant mechanism. Methods: CRP was extracted by ethanol to obtain ethanol extract of Citri reticulatae pericarpium (ECRP). ECRP was then measured by various antioxidant methods, including DNA damage assay, DPPH assay, ABTS assay, Fe3+-reducing assay and Cu2+-reducing assay. Finally, the content of total flavonoids was analyzed by spectrophotometric method. Results: Our results revealed that ECRP could effectively protect against hydroxyl-induced DNA damage (IC50 944.47±147.74 μg/mL). In addition, it could also scavenge DPPH· radical (IC50349.67±1.91 μg/mL) and ABTS+• radical (IC5011.33±0.10 μg/mL), reduce Fe3+ (IC50 140.95±2.15 μg/mL) and Cu2+ (IC50 70.46±1.77 μg/mL). Chemical analysis demonstrated that the content of total flavonoids in ECRP was 198.29±12.24 mg quercetin/g. Conclusion: Citri reticulatae pericarpium can effectively protect against hydroxyl-induced DNA damage. One mechanism of protective effect may be radical-scavenging which is via donating hydrogen atom (H·), donating electron (e). Its antioxidant ability can be mainly attributed to the flavonoids, especially hesperidin and narirutin. PMID:24312832

  5. Involvement of Three Esterase Genes from Panonychus citri (McGregor) in Fenpropathrin Resistance

    PubMed Central

    Shen, Xiao-Min; Liao, Chong-Yu; Lu, Xue-Ping; Wang, Zhe; Wang, Jin-Jun; Dou, Wei

    2016-01-01

    The citrus red mite, Panonychus citri (McGregor), is a major citrus pest with a worldwide distribution and an extensive record of pesticide resistance. However, the underlying molecular mechanism associated with fenpropathrin resistance in this species have not yet been reported. In this study, synergist triphenyl phosphate (TPP) dramatically increased the toxicity of fenpropathrin, suggesting involvement of carboxylesterases (CarEs) in the metabolic detoxification of this insecticide. The subsequent spatiotemporal expression pattern analysis of PcE1, PcE7 and PcE9 showed that three CarEs genes were all over-expressed after insecticide exposure and higher transcripts levels were observed in different field resistant strains of P. citri. Heterologous expression combined with 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetra-zolium bromide (MTT) cytotoxicity assay in Spodoptera frugiperda (Sf9) cells revealed that PcE1-, PcE7- or PcE9-expressing cells showed significantly higher cytoprotective capability than parental Sf9 cells against fenpropathrin, demonstrating that PcEs probably detoxify fenpropathrin. Moreover, gene silencing through the method of leaf-mediated dsRNA feeding followed by insecticide bioassay increased the mortalities of fenpropathrin-treated mites by 31% (PcE1), 27% (PcE7) and 22% (PcE9), respectively, after individual PcE gene dsRNA treatment. In conclusion, this study provides evidence that PcE1, PcE7 and PcE9 are functional genes mediated in fenpropathrin resistance in P. citri and enrich molecular understanding of CarEs during the resistance development of the mite. PMID:27548163

  6. Responsiveness of different citrus genotypes to the Xanthomonas citri ssp. citri-derived pathogen-associated molecular pattern (PAMP) flg22 correlates with resistance to citrus canker.

    PubMed

    Shi, Qingchun; Febres, Vicente J; Jones, Jeffrey B; Moore, Gloria A

    2015-06-01

    The bacterial agent of citrus canker disease (Xanthomonas citri ssp. citri, Xcc) has caused tremendous economic losses to the citrus industry around the world. Pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) is important to plant immunity. In this study, we compared the defence responses of citrus canker-resistant and citrus canker-susceptible genotypes to the Xcc-derived PAMP flg22 (Xflg22) by analysing the expression of 20 citrus defence-associated genes. We showed that, in the most resistant genotype, 'Nagami' kumquat, there was significant induction of several defence genes (EDS1, NDR1, PBS1, RAR1, SGT1, PAL1, NPR2 and NPR3) as early as 6 h and up to 72 h after Xflg22 treatment. At the other end of the spectrum, highly susceptible 'Duncan' grapefruit showed no induction of the same defence genes, even 120 h after treatment. Citrus genotypes with partial levels of resistance showed intermediate levels of transcriptional reprogramming that correlated with their resistance level. Xflg22 also triggered a rapid oxidative burst in all genotypes which was higher and accompanied by the induction of PTI marker genes (WRKY22 and GST1) only in the more resistant genotypes. Pretreatment with Xflg22 prior to Xcc inoculation inhibited bacterial growth in kumquat, but not in grapefruit. A flagellin-deficient Xcc strain (XccΔfliC) showed greater growth increase relative to wild-type Xcc in kumquat than in grapefruit. Taken together, our results indicate that Xflg22 initiates strong PTI in canker-resistant genotypes, but not in susceptible ones, and that a robust induction of PTI is an important component of citrus resistance to canker.

  7. The dual nature of trehalose in citrus canker disease: a virulence factor for Xanthomonas citri subsp. citri and a trigger for plant defence responses

    PubMed Central

    Piazza, Ainelén; Zimaro, Tamara; Garavaglia, Betiana S.; Ficarra, Florencia A.; Thomas, Ludivine; Marondedze, Claudius; Feil, Regina; Lunn, John E.; Gehring, Chris; Ottado, Jorgelina; Gottig, Natalia

    2015-01-01

    Xanthomonas citri subsp. citri (Xcc) is a bacterial pathogen that causes citrus canker in susceptible Citrus spp. The Xcc genome contains genes encoding enzymes from three separate pathways of trehalose biosynthesis. Expression of genes encoding trehalose-6-phosphate synthase (otsA) and trehalose phosphatase (otsB) was highly induced during canker development, suggesting that the two-step pathway of trehalose biosynthesis via trehalose-6-phosphate has a function in pathogenesis. This pathway was eliminated from the bacterium by deletion of the otsA gene. The resulting XccΔotsA mutant produced less trehalose than the wild-type strain, was less resistant to salt and oxidative stresses, and was less able to colonize plant tissues. Gene expression and proteomic analyses of infected leaves showed that infection with XccΔotsA triggered only weak defence responses in the plant compared with infection with Xcc, and had less impact on the host plant’s metabolism than the wild-type strain. These results suggested that trehalose of bacterial origin, synthesized via the otsA–otsB pathway, in Xcc, plays a role in modifying the host plant’s metabolism to its own advantage but is also perceived by the plant as a sign of pathogen attack. Thus, trehalose biosynthesis has both positive and negative consequences for Xcc. On the one hand, it enables this bacterial pathogen to survive in the inhospitable environment of the leaf surface before infection and exploit the host plant’s resources after infection, but on the other hand, it is a tell-tale sign of the pathogen’s presence that triggers the plant to defend itself against infection. PMID:25770587

  8. The dual nature of trehalose in citrus canker disease: a virulence factor for Xanthomonas citri subsp. citri and a trigger for plant defence responses.

    PubMed

    Piazza, Ainelén; Zimaro, Tamara; Garavaglia, Betiana S; Ficarra, Florencia A; Thomas, Ludivine; Marondedze, Claudius; Feil, Regina; Lunn, John E; Gehring, Chris; Ottado, Jorgelina; Gottig, Natalia

    2015-05-01

    Xanthomonas citri subsp. citri (Xcc) is a bacterial pathogen that causes citrus canker in susceptible Citrus spp. The Xcc genome contains genes encoding enzymes from three separate pathways of trehalose biosynthesis. Expression of genes encoding trehalose-6-phosphate synthase (otsA) and trehalose phosphatase (otsB) was highly induced during canker development, suggesting that the two-step pathway of trehalose biosynthesis via trehalose-6-phosphate has a function in pathogenesis. This pathway was eliminated from the bacterium by deletion of the otsA gene. The resulting XccΔotsA mutant produced less trehalose than the wild-type strain, was less resistant to salt and oxidative stresses, and was less able to colonize plant tissues. Gene expression and proteomic analyses of infected leaves showed that infection with XccΔotsA triggered only weak defence responses in the plant compared with infection with Xcc, and had less impact on the host plant's metabolism than the wild-type strain. These results suggested that trehalose of bacterial origin, synthesized via the otsA-otsB pathway, in Xcc, plays a role in modifying the host plant's metabolism to its own advantage but is also perceived by the plant as a sign of pathogen attack. Thus, trehalose biosynthesis has both positive and negative consequences for Xcc. On the one hand, it enables this bacterial pathogen to survive in the inhospitable environment of the leaf surface before infection and exploit the host plant's resources after infection, but on the other hand, it is a tell-tale sign of the pathogen's presence that triggers the plant to defend itself against infection.

  9. Cyclic di-GMP allosterically inhibits the CRP-like protein (Clp) of Xanthomonas axonopodis pv. citri.

    PubMed

    Leduc, Jason L; Roberts, Gary P

    2009-11-01

    The protein Clp from Xanthomonas axonopodis pv. citri regulates pathogenesis and is a member of the CRP (cyclic AMP receptor protein) superfamily. We show that unlike the DNA-binding activity of other members of this family, the DNA-binding activity of Clp is allosterically inhibited by its effector and that cyclic di-GMP serves as that effector at physiological concentrations.

  10. Characterization of Xanthomonas axonopodis pv. citri LexA: recognition of the LexA binding site.

    PubMed

    Yang, M-K; Yang, Y-C; Hsu, C-H

    2002-12-01

    Levels of l exA transcripts are markedly increased upon exposure of Xanthomonas axonopodis pathovar citri ( X. a. pv. citri) to the DNA-damaging agent mitomycin C. Preliminary electrophoretic mobility-shift data led us to propose that binding of LexA protein to the sequence upstream of the lexA coding region is responsible for low promoter activity in the uniduced state. We determined that the LexA protein binds to the region located between the transcription start site and the translation initiation codon of the lexA gene of X. a. pv. citri. Using a DNase I footprinting technique, we identified a 19-bp palindromic sequence, TTAGTAGTAATACTACTAA (TTAGN(11)CTAA), located in this region as the binding sequence for the LexA protein of X. a. pv. citri, and showed that the two halves of the palindrome have to be in the inverted repeat orientation to permit binding of LexA. We also showed that almost any mutation in this sequence, including changes in the length of the spacer region of the palindrome, destroyed its ability to bind LexA both in vitro and in vivo.

  11. Complete genome sequence of Spiroplasma citri strain R8-A2T, causal agent of stubborn disease in Citrus spp.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spiroplasma citri is the causal agent of stubborn disease in Citrus spp., as well as the cause of diseases in numerous other plant genera. Here we report the nucleotide sequence of the 1,599,709 bp circular chromosome and two plasmids of strain R8-A2T. This information will facilitate comparative ...

  12. The relationship between PthA expression and the pathogenicity of Xanthomonas axonopodis pv. citri.

    PubMed

    Li, Na; Huang, Long; Liu, Liping; Li, Dazhi; Dai, Suming; Deng, Ziniu

    2014-02-01

    Citrus canker disease, caused by Xanthomonas axonopodis pv. citri, affects almost all citrus species and cultivars and hascaused severe damage to the citrus industry worldwide. PthA is considered the main pathogenesis effector of the pathogen. This research aimed to temporally and spatially analyze the expression of the PthA protein of the bactrium during its culture, and then try to understand the relationship between the PthA expression levels and the pathogenicity. The relationship between the expression of PthA and the pathogenicity of X. axonopodis pv. citri was fully investigated by using SDS-PAGE, Western blot, ELISA and field inoculation, It was found that bacteria cultured for 36 h had the highest expression of PthA and showed the most virulent pathogenicity. The conservation duration of the pathogen isolates influenced their PthA expression and the pathogenicity, and negative relationship between the duration and the expression of PthA and pathogenicity. When the stored pathogen bacteria were cultured in liquid LB medium, they were able to regain activated, showing higher PthA expression level and enhanced pathogenicity, even though the activity was inferior, in terms of both PthA expression and pathogenicity, than the freshly isolated ones. Seven isolates from different citrus orchards displayed almost identical protein expression profiles. It could conclude that the expressions of PthA was positively related to pathogenicity.

  13. Development and reproduction of Panonychus citri (Prostigmata: Tetranychidae) on different species and varieties of citrus plants.

    PubMed

    Zanardi, Odimar Zanuzo; Bordini, Gabriela Pavan; Franco, Aline Aparecida; de Morais, Matheus Rovere; Yamamoto, Pedro Takao

    2015-12-01

    The species and varieties of citrus plants that are currently grown can favor the population growth of the citrus red mite Panonychus citri (McGregor) (Prostigmata: Tetranychidae) and alter the pest management programs in citrus groves. In this study we evaluated, in the laboratory, the development and reproduction of P. citri and estimated its life table parameters when reared on four varieties of Citrus sinensis (L.) Osbeck (Valencia, Pera, Natal, and Hamlin), one variety of Citrus reticulata Blanco (Ponkan) and one variety of Citrus limon (L.) Burm. (Sicilian). The incubation period and egg viability were not affected by the host plant. However, the development and survival of the immature stage were significantly lower on Hamlin orange than on Valencia, Pera and Natal oranges, Ponkan mandarin and Sicilian lemon. The fecundity and oviposition period of females were lower on Hamlin orange than on the other hosts. Mites reared on Valencia orange and Sicilian lemon had a higher net reproductive rate (R 0 ), intrinsic growth rate (r) and finite rate of increase (λ), and a shorter interval between generations (T) than on Pera, Natal and Hamlin oranges and Ponkan mandarin. On the other hand, mites reared on Hamlin orange had the lowest R 0 , r and λ and the highest T among the hosts. Based on the results obtained we recommend that for Valencia orange and Sicilian lemon, the mite monitoring programs should be more intense to detect the initial infestation of pest, avoiding the damage in plants and the increase in production costs.

  14. A LOV protein modulates the physiological attributes of Xanthomonas axonopodis pv. citri relevant for host plant colonization.

    PubMed

    Kraiselburd, Ivana; Alet, Analía I; Tondo, María Laura; Petrocelli, Silvana; Daurelio, Lucas D; Monzón, Jesica; Ruiz, Oscar A; Losi, Aba; Orellano, Elena G

    2012-01-01

    Recent studies have demonstrated that an appropriate light environment is required for the establishment of efficient vegetal resistance responses in several plant-pathogen interactions. The photoreceptors implicated in such responses are mainly those belonging to the phytochrome family. Data obtained from bacterial genome sequences revealed the presence of photosensory proteins of the BLUF (Blue Light sensing Using FAD), LOV (Light, Oxygen, Voltage) and phytochrome families with no known functions. Xanthomonas axonopodis pv. citri is a Gram-negative bacterium responsible for citrus canker. The in silico analysis of the X. axonopodis pv. citri genome sequence revealed the presence of a gene encoding a putative LOV photoreceptor, in addition to two genes encoding BLUF proteins. This suggests that blue light sensing could play a role in X. axonopodis pv. citri physiology. We obtained the recombinant Xac-LOV protein by expression in Escherichia coli and performed a spectroscopic analysis of the purified protein, which demonstrated that it has a canonical LOV photochemistry. We also constructed a mutant strain of X. axonopodis pv. citri lacking the LOV protein and found that the loss of this protein altered bacterial motility, exopolysaccharide production and biofilm formation. Moreover, we observed that the adhesion of the mutant strain to abiotic and biotic surfaces was significantly diminished compared to the wild-type. Finally, inoculation of orange (Citrus sinensis) leaves with the mutant strain of X. axonopodis pv. citri resulted in marked differences in the development of symptoms in plant tissues relative to the wild-type, suggesting a role for the Xac-LOV protein in the pathogenic process. Altogether, these results suggest the novel involvement of a photosensory system in the regulation of physiological attributes of a phytopathogenic bacterium. A functional blue light receptor in Xanthomonas spp. has been described for the first time, showing an important

  15. A novel two-component response regulator links rpf with biofilm formation and virulence of Xanthomonas axonopodis pv. citri.

    PubMed

    Huang, Tzu-Pi; Lu, Kuan-Min; Chen, Yu-Hsuan

    2013-01-01

    Citrus bacterial canker caused by Xanthomonas axonopodis pv. citri is a serious disease that impacts citrus production worldwide, and X. axonopodis pv. citri is listed as a quarantine pest in certain countries. Biofilm formation is important for the successful development of a pathogenic relationship between various bacteria and their host(s). To understand the mechanisms of biofilm formation by X. axonopodis pv. citri strain XW19, the strain was subjected to transposon mutagenesis. One mutant with a mutation in a two-component response regulator gene that was deficient in biofilm formation on a polystyrene microplate was selected for further study. The protein was designated as BfdR for biofilm formation defective regulator. BfdR from strain XW19 shares 100% amino acid sequence identity with XAC1284 of X. axonopodis pv. citri strain 306 and 30-100% identity with two-component response regulators in various pathogens and environmental microorganisms. The bfdR mutant strain exhibited significantly decreased biofilm formation on the leaf surfaces of Mexican lime compared with the wild type strain. The bfdR mutant was also compromised in its ability to cause canker lesions. The wild-type phenotype was restored by providing pbfdR in trans in the bfdR mutant. Our data indicated that BfdR did not regulate the production of virulence-related extracellular enzymes including amylase, lipase, protease, and lecithinase or the expression of hrpG, rfbC, and katE; however, BfdR controlled the expression of rpfF in XVM2 medium, which mimics cytoplasmic fluids in planta. In conclusion, biofilm formation on leaf surfaces of citrus is important for canker development in X. axonopodis pv. citri XW19. The process is controlled by the two-component response regulator BfdR via regulation of rpfF, which is required for the biosynthesis of a diffusible signal factor.

  16. KatG, the Bifunctional Catalase of Xanthomonas citri subsp. citri, Responds to Hydrogen Peroxide and Contributes to Epiphytic Survival on Citrus Leaves.

    PubMed

    Tondo, María Laura; Delprato, María Laura; Kraiselburd, Ivana; Fernández Zenoff, María Verónica; Farías, María Eugenia; Orellano, Elena G

    2016-01-01

    Xanthomonas citri subsp. citri (Xcc) is the bacterium responsible for citrus canker. This bacterium is exposed to reactive oxygen species (ROS) at different points during its life cycle, including those normally produced by aerobic respiration or upon exposition to ultraviolet (UV) radiation. Moreover, ROS are key components of the host immune response. Among enzymatic ROS-detoxifying mechanisms, catalases eliminate H2O2, avoiding the potential damage caused by this specie. Xcc genome includes four catalase genes. In this work, we studied the physiological role of KatG, the only bifunctional catalase of Xcc, through the construction and characterization of a modified strain (XcckatG), carrying an insertional mutation in the katG gene. First, we evaluated the involvement of KatG in the bacterial adaptive response to H2O2. XcckatG cultures exhibited lower catalase activity than those of the wild-type strain, and this activity was not induced upon treatment with sub-lethal doses of H2O2. Moreover, the KatG-deficient mutant exhibited decreased tolerance to H2O2 toxicity compared to wild-type cells and accumulated high intracellular levels of peroxides upon exposure to sub-lethal concentrations of H2O2. To further study the role of KatG in Xcc physiology, we evaluated bacterial survival upon exposure to UV-A or UV-B radiation. In both conditions, XcckatG showed a high mortality in comparison to Xcc wild-type. Finally, we studied the development of bacterial biofilms. While structured biofilms were observed for the Xcc wild-type, the development of these structures was impaired for XcckatG. Based on these results, we demonstrated that KatG is responsible for Xcc adaptive response to H2O2 and a key component of the bacterial response to oxidative stress. Moreover, this enzyme plays an important role during Xcc epiphytic survival, being essential for biofilm formation and UV resistance.

  17. KatG, the Bifunctional Catalase of Xanthomonas citri subsp. citri, Responds to Hydrogen Peroxide and Contributes to Epiphytic Survival on Citrus Leaves

    PubMed Central

    Tondo, María Laura; Delprato, María Laura; Kraiselburd, Ivana; Fernández Zenoff, María Verónica; Farías, María Eugenia; Orellano, Elena G.

    2016-01-01

    Xanthomonas citri subsp. citri (Xcc) is the bacterium responsible for citrus canker. This bacterium is exposed to reactive oxygen species (ROS) at different points during its life cycle, including those normally produced by aerobic respiration or upon exposition to ultraviolet (UV) radiation. Moreover, ROS are key components of the host immune response. Among enzymatic ROS-detoxifying mechanisms, catalases eliminate H2O2, avoiding the potential damage caused by this specie. Xcc genome includes four catalase genes. In this work, we studied the physiological role of KatG, the only bifunctional catalase of Xcc, through the construction and characterization of a modified strain (XcckatG), carrying an insertional mutation in the katG gene. First, we evaluated the involvement of KatG in the bacterial adaptive response to H2O2. XcckatG cultures exhibited lower catalase activity than those of the wild-type strain, and this activity was not induced upon treatment with sub-lethal doses of H2O2. Moreover, the KatG-deficient mutant exhibited decreased tolerance to H2O2 toxicity compared to wild-type cells and accumulated high intracellular levels of peroxides upon exposure to sub-lethal concentrations of H2O2. To further study the role of KatG in Xcc physiology, we evaluated bacterial survival upon exposure to UV-A or UV-B radiation. In both conditions, XcckatG showed a high mortality in comparison to Xcc wild-type. Finally, we studied the development of bacterial biofilms. While structured biofilms were observed for the Xcc wild-type, the development of these structures was impaired for XcckatG. Based on these results, we demonstrated that KatG is responsible for Xcc adaptive response to H2O2 and a key component of the bacterial response to oxidative stress. Moreover, this enzyme plays an important role during Xcc epiphytic survival, being essential for biofilm formation and UV resistance. PMID:26990197

  18. A survey of FLS2 genes from multiple citrus species identifies candidates for enhancing disease resistance to Xanthomonas citri ssp. citri.

    PubMed Central

    Shi, Qingchun; Febres, Vicente J; Jones, Jeffrey B; Moore, Gloria A

    2016-01-01

    Pathogen-associated molecular patterns (PAMPs)-triggered immunity (PTI) is an important component of plant innate immunity. In a previous study, we showed that the PAMP flg22 from Xanthomonas citri ssp. citri (Xflg22), the causal agent of citrus canker, induced PTI in citrus, which correlated with the observed levels of canker resistance. Here, we identified and sequenced two bacterial flagellin/flg22 receptors (FLS2-1 and FLS2-2) from ‘Duncan’ grapefruit (Citrus paradisi, CpFLS2-1 and CpFLS2-2) and ‘Sun Chu Sha’ mandarin (C. reticulata, CrFLS2-1 and CrFLS2-2). We were able to isolate only one FLS2 from ‘Nagami’ kumquat (Fortunella margarita, FmFLS2-1) and gene flanking sequences suggest a rearrangement event that resulted in the deletion of FLS2-2 from the genome. Phylogenetic analysis, gene structure and presence of critical amino acid domains all indicate we identified the true FLS2 genes in citrus. FLS2-2 was more transcriptionally responsive to Xflg22 than FLS2-1, with induced expression levels higher in canker-resistant citrus than in susceptible ones. Interestingly, ‘Nagami’ kumquat showed the highest FLS2-1 steady-state expression levels, although it was not induced by Xflg22. We selected FmFLS2-1, CrFLS2-2 and CpFLS2-2 to further evaluate their capacity to enhance bacterial resistance using Agrobacterium-mediated transient expression assays. Both FmFLS2-1 and CrFLS2-2, the two proteins from canker-resistant species, conferred stronger Xflg22 responses and reduced canker symptoms in leaves of the susceptible grapefruit genotype. These two citrus genes will be useful resources to enhance PTI and achieve resistance against canker and possibly other bacterial pathogens in susceptible citrus types. PMID:27222722

  19. Incidence of Candidatus Liberibacter asiaticus infection in abandoned citrus occurring in proximity to commercially managed groves.

    PubMed

    Tiwari, Siddharth; Lewis-Rosenblum, Hannah; Pelz-Stelinski, Kirsten; Stelinski, Lukasz L

    2010-12-01

    Huanglongbing is one of the most devastating diseases of citrus (Citrus spp.). One management tactic against huanglongbing is aggressive management of the vector, the Asian citrus psyllid (Diaphorina citri Kuwayama), with insecticide applications. However, D. citri in abandoned groves are not controlled and therefore pose a risk of reinfestation for nearby commercial citrus. These abandoned groves could serve as a reservoir for the vector, as well as a source of the presumed causal agent for huanglongbing in Florida, Candidatus Liberibacter asiaticus (Las). The current study was conducted to determine the degree to which Las is present in abandoned Florida citrus groves and to compare relative inoculum levels in nearby managed and abandoned groves during times of the year when D. citri are abundant (June, July, and August). In addition, the movement of Las by dispersing D. citri adults from inner and edge rows of abandoned grove plots to the corresponding rows of managed plots was quantified during the same 3 mo. The results of the current study confirmed the presence of Las in both D. citri and plant tissue in abandoned groves at statistically equivalent levels to those in nearby managed groves. The mean number of D. citri adults dispersing from abandoned to managed grove plots ranged from 7.25 +/- 1.70 to 70.25 +/- 21.25 per 4-d intervals. Of those, the mean number of dispersing D. citri adults that were carrying the Las pathogen ranged from 1.00 +/- 0.58 to 1.50 +/- 0.50. Our results indicate that abandoned citrus groves are a significant source of Ca. Las and that dispersing D. citri move this pathogen into nearby managed groves.

  20. Identification and characterization of a second lexA gene of Xanthomonas axonopodis Pathovar citri.

    PubMed

    Yang, Mei-Kwei; Su, Shu-Ray; Sung, Vin-Long

    2005-07-01

    We previously identified and characterized a lexA gene from Xanthomonas axonopodis pv. citri. For this study, we cloned and expressed a lexA homologue from X. axonopodis pv. citri. This gene was designated lexA2, and the previously identified lexA gene was renamed lexA1. The coding region of lexA2 is 606 bp long and shares 59% nucleotide sequence identity with lexA1. Analyses of the deduced amino acid sequence revealed that LexA2 has structures that are characteristic of LexA proteins, including a helix-turn-helix DNA binding domain and conserved amino acid residues required for the autocleavage of LexA. The lexA2 mutant, which was constructed by gene replacement, was 4 orders of magnitude more resistant to the DNA-damaging agent mitomycin C at 0.1 microg/ml and 1 order of magnitude more resistant to another DNA-damaging agent, methylmethane sulfonate at 30 microg/ml, than the wild type. A lexA1 lexA2 double mutant had the same degree of susceptibility to mitomycin C as the lexA1 or lexA2 single mutant but was 1 order of magnitude more resistant to methylmethane sulfonate at 30 microg/ml than the lexA1 or lexA2 single mutant. These results suggest that LexA1 and LexA2 play different roles in regulating the production of methyltransferases that are required for repairing DNA damage caused by methylmethane sulfonate. A mitomycin C treatment also caused LexA2 to undergo autocleavage, as seen with LexA1. The results of electrophoresis mobility shift assays revealed that LexA2 does not bind the lexA1 promoter. It binds to both the lexA2 and recA promoters. However, neither LexA2 nor LexA1 appears to regulate recA expression, as lexA1, lexA2, and lexA1 lexA2 mutants did not become constitutive for recA transcription and RecA production. These results suggest that recA expression in X. axonopodis pv. citri is regulated by mechanisms that have yet to be identified.

  1. Structural insights on two hypothetical secretion chaperones from Xanthomonas axonopodis pv. citri.

    PubMed

    Fattori, Juliana; Prando, Alessandra; Assis, Leandro H P; Aparicio, Ricardo; Tasic, Ljubica

    2011-06-01

    Several Gram-negative bacterial pathogens have developed type III secretion systems (T3SSs) to deliver virulence proteins directly into eukaryotic cells in a process essential for many diseases. The type III secretion processes require customized chaperones with high specificity for binding partners, thus providing the secretion to occur. Due to the very low sequence similarities among secretion chaperones, annotation and discrimination of a great majority of them is extremely difficult and a task with low scores even if genes are encountered that codify for small (<20 kDa) proteins with low pI and a tendency to dimerise. Concerning about this, herein, we present structural features on two hypothetical T3SSs chaperones belonging to plant pathogen Xanthomonas axonopodis pv. citri and suggest how low resolution models based on Small Angle X-ray Scattering patterns can provide new structural insights that could be very helpful in their analysis and posterior classification.

  2. Glutamate transport and xanthan gum production in the plant pathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Rojas, Robert; Nishidomi, Sabrina; Nepomuceno, Roberto; Oshiro, Elisa; de Cassia Café Ferreira, Rita

    2013-11-01

    L-glutamate plays a central role in nitrogen metabolism in all living organisms. In the genus Xanthomonas, the nitrogen nutrition is an important factor involved in the xanthan gum production, an important exopolysaccharide with various industrial and biotechnological applications. In this report, we demonstrate that the use of L-glutamate by the phytopathogen Xanthomonas axonopodis pv. citri as a nitrogen source in defined medium significantly increases the production of xanthan gum. This increase is dependent on the L-glutamate concentration. In addition, we have also characterized a glutamate transport system that is dependent on a proton gradient and on ATP and is modulated by amino acids that are structurally related to glutamate. This is the first biochemical characterization of an energy substrate transport system observed in a bacterial phytopathogen with a broad economic and industrial impact due to xanthan gum production.

  3. Cloning and molecular characterization of hrpX from Xanthomonas axonopodis pv. citri.

    PubMed

    Iwamoto, M; Oku, T

    2000-01-01

    The hrpX gene of plant pathogenic Xanthomonas species is essential for pathogenicity on host plants and to cause hypersensitive reaction on non-host plants. We cloned and analyzed a hrpX homologue, designated hrpXct, of X. axonopodis pv. citri, a pathogen of citrus canker. The open reading frame of hrpXct has 1431 bp in nucleotides which has a coding capacity of 476 amino acid residues with a molecular mass of 52.4 kDa. The predicted amino acid sequence of HrpXct has 90% identity to the AraC family type transcriptional activator protein HrpXc of X. campestris pv. campestris, 95% to HrpXo of X. oryzae pv. oryzae and 97% to X. vesicatoria. These findings clearly indicate and confirm that the structure of the hrpX genes in plant pathogenic Xanthomonas species is highly conserved.

  4. Chemotactic signal transduction and phosphate metabolism as adaptive strategies during citrus canker induction by Xanthomonas citri.

    PubMed

    Moreira, Leandro Marcio; Facincani, Agda Paula; Ferreira, Cristiano Barbalho; Ferreira, Rafael Marine; Ferro, Maria Inês Tiraboshi; Gozzo, Fabio Cesar; de Oliveira, Julio Cezar Franco; Ferro, Jesus Aparecido; Soares, Márcia Regina

    2015-03-01

    The genome of Xanthomonas citri subsp. Citri strain 306 pathotype A (Xac) was completely sequenced more than 10 years; to date, few studies involving functional genomics Xac and its host compatible have been developed, specially related to adaptive events that allow the survival of Xac within the plant. Proteomic analysis of Xac showed that the processes of chemotactic signal transduction and phosphate metabolism are key adaptive strategies during the interaction of a pathogenic bacterium with its plant host. The results also indicate the importance of a group of proteins that may not be directly related to the classical virulence factors, but that are likely fundamental to the success of the initial stages of the infection, such as methyl-accepting chemotaxis protein (Mcp) and phosphate specific transport (Pst). Furthermore, the analysis of the mutant of the gene pstB which codifies to an ABC phosphate transporter subunit revealed a complete absence of citrus canker symptoms when inoculated in compatible hosts. We also conducted an in silico analysis which established the possible network of genes regulated by two-component systems PhoPQ and PhoBR (related to phosphate metabolism), and possible transcriptional factor binding site (TFBS) motifs of regulatory proteins PhoB and PhoP, detaching high degree of conservation of PhoB TFBS in 84 genes of Xac genome. This is the first time that chemotaxis signal transduction and phosphate metabolism were therefore indicated to be fundamental to the process of colonization of plant tissue during the induction of disease associated with Xanthomonas genus bacteria.

  5. Structural analysis and involvement in plant innate immunity of Xanthomonas axonopodis pv. citri lipopolysaccharide.

    PubMed

    Casabuono, Adriana; Petrocelli, Silvana; Ottado, Jorgelina; Orellano, Elena G; Couto, Alicia S

    2011-07-22

    Xanthomonas axonopodis pv. citri (Xac) causes citrus canker, provoking defoliation and premature fruit drop with concomitant economical damage. In plant pathogenic bacteria, lipopolysaccharides are important virulence factors, and they are being increasingly recognized as major pathogen-associated molecular patterns for plants. In general, three domains are recognized in a lipopolysaccharide: the hydrophobic lipid A, the hydrophilic O-antigen polysaccharide, and the core oligosaccharide, connecting lipid A and O-antigen. In this work, we have determined the structure of purified lipopolysaccharides obtained from Xanthomonas axonopodis pv. citri wild type and a mutant of the O-antigen ABC transporter encoded by the wzt gene. High pH anion exchange chromatography and matrix-assisted laser desorption/ionization mass spectrum analysis were performed, enabling determination of the structure not only of the released oligosaccharides and lipid A moieties but also the intact lipopolysaccharides. The results demonstrate that Xac wild type and Xacwzt LPSs are composed mainly of a penta- or tetra-acylated diglucosamine backbone attached to either two pyrophosphorylethanolamine groups or to one pyrophosphorylethanolamine group and one phosphorylethanolamine group. The core region consists of a branched oligosaccharide formed by Kdo₂Hex₆GalA₃Fuc3NAcRha₄ and two phosphate groups. As expected, the presence of a rhamnose homo-oligosaccharide as O-antigen was determined only in the Xac wild type lipopolysaccharide. In addition, we have examined how lipopolysaccharides from Xac function in the pathogenesis process. We analyzed the response of the different lipopolysaccharides during the stomata aperture closure cycle, the callose deposition, the expression of defense-related genes, and reactive oxygen species production in citrus leaves, suggesting a functional role of the O-antigen from Xac lipopolysaccharides in the basal response.

  6. Structural Analysis and Involvement in Plant Innate Immunity of Xanthomonas axonopodis pv. citri Lipopolysaccharide*

    PubMed Central

    Casabuono, Adriana; Petrocelli, Silvana; Ottado, Jorgelina; Orellano, Elena G.; Couto, Alicia S.

    2011-01-01

    Xanthomonas axonopodis pv. citri (Xac) causes citrus canker, provoking defoliation and premature fruit drop with concomitant economical damage. In plant pathogenic bacteria, lipopolysaccharides are important virulence factors, and they are being increasingly recognized as major pathogen-associated molecular patterns for plants. In general, three domains are recognized in a lipopolysaccharide: the hydrophobic lipid A, the hydrophilic O-antigen polysaccharide, and the core oligosaccharide, connecting lipid A and O-antigen. In this work, we have determined the structure of purified lipopolysaccharides obtained from Xanthomonas axonopodis pv. citri wild type and a mutant of the O-antigen ABC transporter encoded by the wzt gene. High pH anion exchange chromatography and matrix-assisted laser desorption/ionization mass spectrum analysis were performed, enabling determination of the structure not only of the released oligosaccharides and lipid A moieties but also the intact lipopolysaccharides. The results demonstrate that Xac wild type and Xacwzt LPSs are composed mainly of a penta- or tetra-acylated diglucosamine backbone attached to either two pyrophosphorylethanolamine groups or to one pyrophosphorylethanolamine group and one phosphorylethanolamine group. The core region consists of a branched oligosaccharide formed by Kdo2Hex6GalA3Fuc3NAcRha4 and two phosphate groups. As expected, the presence of a rhamnose homo-oligosaccharide as O-antigen was determined only in the Xac wild type lipopolysaccharide. In addition, we have examined how lipopolysaccharides from Xac function in the pathogenesis process. We analyzed the response of the different lipopolysaccharides during the stomata aperture closure cycle, the callose deposition, the expression of defense-related genes, and reactive oxygen species production in citrus leaves, suggesting a functional role of the O-antigen from Xac lipopolysaccharides in the basal response. PMID:21596742

  7. Mutation in the xpsD gene of Xanthomonas axonopodis pv. citri affects cellulose degradation and virulence.

    PubMed

    Baptista, Juliana Cristina; Machado, Marcos Antonio; Homem, Rafael Augusto; Torres, Pablo Sebastián; Vojnov, Adrian Alberto; do Amaral, Alexandre Morais

    2010-01-01

    The Gram-negative bacterium Xanthomonas axonopodis pv. citri, the causal agent of citrus canker, is a major threat to the citrus industry worldwide. Although this is a leaf spot pathogen, it bears genes highly related to degradation of plant cell walls, which are typically found in plant pathogens that cause symptoms of tissue maceration. Little is known on Xac capacity to cause disease and hydrolyze cellulose. We investigated the contribution of various open reading frames on degradation of a cellulose compound by means of a global mutational assay to selectively screen for a defect in carboxymethyl cellulase (CMCase) secretion in X. axonopodis pv. citri. Screening on CMC agar revealed one mutant clone defective in extracellular glycanase activity, out of nearly 3,000 clones. The insertion was located in the xpsD gene, a component of the type II secretion system (T2SS) showing an influence in the ability of Xac to colonize tissues and hydrolyze cellulose. In summary, these data show for the first time, that X. axonopodis pv. citri is capable of hydrolyzing cellulose in a T2SS-dependent process. Furthermore, it was demonstrated that the ability to degrade cellulose contributes to the infection process as a whole.

  8. Crystallization and preliminary X-ray diffraction analysis of the phosphate-binding protein PhoX from Xanthomonas citri.

    PubMed

    Pegos, Vanessa R; Medrano, Francisco Javier; Balan, Andrea

    2014-12-01

    Xanthomonas axonopodis pv. citri (X. citri) is an important bacterium that causes citrus canker disease in plants in Brazil and around the world, leading to significant economic losses. Determination of the physiology and mechanisms of pathogenesis of this bacterium is an important step in the development of strategies for its containment. Phosphate is an essential ion in all microrganisms owing its importance during the synthesis of macromolecules and in gene and protein regulation. Interestingly, X. citri has been identified to present two periplasmic binding proteins that have not been further characterized: PstS, from an ATP-binding cassette for high-affinity uptake and transport of phosphate, and PhoX, which is encoded by an operon that also contains a putative porin for the transport of phosphate. Here, the expression, purification and crystallization of the phosphate-binding protein PhoX and X-ray data collection at 3.0 Å resolution are described. Biochemical, biophysical and structural data for this protein will be helpful in the elucidation of its function in phosphate uptake and the physiology of the bacterium.

  9. Crystallization and preliminary X-ray diffraction analysis of the phosphate-binding protein PhoX from Xanthomonas citri

    PubMed Central

    Pegos, Vanessa R.; Medrano, Francisco Javier; Balan, Andrea

    2014-01-01

    Xanthomonas axonopodis pv. citri (X. citri) is an important bacterium that causes citrus canker disease in plants in Brazil and around the world, leading to significant economic losses. Determination of the physiology and mechanisms of pathogenesis of this bacterium is an important step in the development of strategies for its containment. Phosphate is an essential ion in all microrganisms owing its importance during the synthesis of macromolecules and in gene and protein regulation. Interestingly, X. citri has been identified to present two periplasmic binding proteins that have not been further characterized: PstS, from an ATP-binding cassette for high-affinity uptake and transport of phosphate, and PhoX, which is encoded by an operon that also contains a putative porin for the transport of phosphate. Here, the expression, purification and crystallization of the phosphate-binding protein PhoX and X-ray data collection at 3.0 Å resolution are described. Biochemical, biophysical and structural data for this protein will be helpful in the elucidation of its function in phosphate uptake and the physiology of the bacterium. PMID:25484207

  10. Mutation in the xpsD gene of Xanthomonas axonopodis pv. citri affects cellulose degradation and virulence

    PubMed Central

    2010-01-01

    The Gram-negative bacterium Xanthomonas axonopodis pv. citri, the causal agent of citrus canker, is a major threat to the citrus industry worldwide. Although this is a leaf spot pathogen, it bears genes highly related to degradation of plant cell walls, which are typically found in plant pathogens that cause symptoms of tissue maceration. Little is known on Xac capacity to cause disease and hydrolyze cellulose. We investigated the contribution of various open reading frames on degradation of a cellulose compound by means of a global mutational assay to selectively screen for a defect in carboxymethyl cellulase (CMCase) secretion in X. axonopodis pv. citri. Screening on CMC agar revealed one mutant clone defective in extracellular glycanase activity, out of nearly 3,000 clones. The insertion was located in the xpsD gene, a component of the type II secretion system (T2SS) showing an influence in the ability of Xac to colonize tissues and hydrolyze cellulose. In summary, these data show for the first time, that X. axonopodis pv. citri is capable of hydrolyzing cellulose in a T2SS-dependent process. Furthermore, it was demonstrated that the ability to degrade cellulose contributes to the infection process as a whole. PMID:21637619

  11. PilR enhances the sensitivity of Xanthomonas axonopodis pv. citri to the infection of filamentous bacteriophage Cf.

    PubMed

    Yang, Yen-Chun; Chou, Chun-Ping; Kuo, Tsong-Teh; Lin, Shan-Hwa; Yang, Mei-Kwei

    2004-04-01

    The pilA gene, which encodes the major structure of pili, is required for infection of Xanthomonas axonopodis pv. citri ( X. a. pv. citri) by the filamentous bacteriophage Cf. Two open reading frames (ORFs) located downstream of pilA were cloned and characterized. One 1392-bp ORF encodes a protein of 464 amino acids which shares substantial similarity with pilR of other bacterial species; the second ORF ( orf618), of 1854-bp, shares sequence similarity with pilS. The existence of the pilR-like and pilS-like genes in various X. campestris pathovars indicated that these two genes are well conserved in Xanthomonas. pilR and pilS mutants were constructed by gene replacement. We found that a pilR mutant, resistant to the infection of phage Cf, was unable to synthesize PilA protein; however, the abundance of the PilA protein and of the pilA transcript was markedly increased by the introduction of a plasmid containing the cloned pilR gene. The restoration of the normal pilus-specific sensitivity of this transformed clone to Cf indicated that the pilR gene functions as a transcriptional regulator of pilA. The pilS mutant, however, was susceptible to Cf infection, and the level of pilA expression in this mutant was similar to that of wild-type cells. Promoter analysis of luciferase reporter gene constructs containing the 5' untranslated regions of pilR or pilS genes revealed that, although the pilR and pilS are contiguous in X. a. pv. citri, the two genes are expressed independently, and the strong pilR promoter leads to the accumulation of PilR in X. a. pv. citri, which positively regulates the biosynthesis of PilA. These results revealed the enhanced sensitivity of X. a. pv. citri to phage Cf in the presence of PilR and indicated that the filamentous phage Cf utilize bacterial pili as a receptor site for its infection.

  12. Annotation of the Asian citrus psyllid genome reveals a reduced innate immune system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus production worldwide is currently facing significant losses due to citrus greening disease, also known as huanglongbing. The citrus greening bacteria, Candidatus Liberibacter asiaticus (CLas), is a persistent propagative pathogen transmitted by the Asian citrus psyllid, Diaphorina citri Kuway...

  13. Comparative anaylsis of Asian citrus psyllid and potato psyllid antennae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The comparative investigation of the morphological basis for olfactory reception in the Asian citrus psyllid (Diaphorina citri) and the potato/tomato psyllid (Bactericera cockerelli (Hemiptera: Psyllidae) was performed using scanning electron microscopy to elucidate the antennal sensory arrays being...

  14. Safety assessment of (-)-hydroxycitric acid and Super CitriMax, a novel calcium/potassium salt.

    PubMed

    Soni, M G; Burdock, G A; Preuss, H G; Stohs, S J; Ohia, S E; Bagchi, D

    2004-09-01

    (-)-Hydroxycitric acid (HCA) is a principle constituent (10-30%) of the dried fruit rind of Garcinia cambogia, a plant native to Southeastern Asia. The dried rind has been used for centuries throughout Southeast Asia as a food preservative, flavoring agent and carminative. Extensive experimental studies show that HCA inhibits fat synthesis and reduces food intake. The objective of this review is to systematically review the available safety/toxicity literature on HCA to determine its safety in-use. The primary mechanism of action of HCA appears to be related to its ability to act as a competitive inhibitor of the enzyme ATP-citrate lyase, which catalyzes the conversion of citrate and coenzyme A to oxaloacetate and acetyl coenzyme A (acetyl-CoA), primary building blocks of fatty acid and cholesterol synthesis. Super CitriMax, a novel calcium/potassium-HCA extract (HCA-SX), is considerably more soluble and bioavailable than calcium-based HCA ingredients. Acute oral toxicity studies in animals demonstrate that CitriMax (50% HCA as calcium salt) has a low acute oral toxicity. In a subchronic study in rats, the gavage administration of HCA-SX at doses up to 2500 mg/kg/day for a period of 90 days caused a significant decrease in body weight and reduction in feed consumption without any adverse effects. The structure, mechanism of action, long history of use of HCA and other toxicity studies indicate that HCA-SX is unlikely to cause reproductive or developmental effects. HCA-SX was not mutagenic in the presence or absence of metabolic activation in Ames genotoxicity assays in strains TA98 and TA102. HCA-SX-induced increases in number of revertants in other strains (TA100 and TA1535 in the absence of metabolic activation and in strain TA1537 in the presence of metabolic activation) but these were not considered as biologically indicative of a mutagenic effect. In several, placebo-controlled, double-blind trials employing up to 2800 mg/day HCA, no treatment-related adverse

  15. Polymerase chain reaction-restriction fragment length polymorphism method to distinguish three mealybug groups within the Planococcus citri-P. minor species complex (Hemiptera: Coccoidea: Pseudococcidae).

    PubMed

    Rung, A; Miller, D R; Scheffer, S J

    2009-02-01

    The mealybug species Planococcus citri (Risso) and Planococcus minor (Maskell) (Hemiptera: Coccoidea: Pseudococcidae) have special significance to U.S. quarantine and U.S. agriculture. Commonly intercepted at U.S. ports-of-entry, they are difficult to identify based on morphological characters. This study presents a molecular method for distinguishing P. citri, P. minor, and a genetically distinct group that is morphologically identical to P. citri, from Hawaii. This method uses polymerase chain reaction (PCR) followed by restriction fragment polymorphism analysis (RFLP) using the restriction enzymes BspH1, BsmH1, and HpH1. The resulting band patterns can be visualized in a 2% agarose gel and are sufficient to differentiate between the three entities mentioned above. PCR-RFLP diagnostics can be used for all life stages and is cheaper and faster than DNA sequencing.

  16. Structure-Function Analysis of the HrpB2-HrcU Interaction in the Xanthomonas citri Type III Secretion System

    PubMed Central

    Cappelletti, Paola A.; dos Santos, Rafael Freitas; do Amaral, Alexandre M.; Homem, Rafael Augusto; dos Santos Souza, Thaís; Machado, Marcos A.; Farah, Chuck S.

    2011-01-01

    Bacterial type III secretion systems deliver protein virulence factors to host cells. Here we characterize the interaction between HrpB2, a small protein secreted by the Xanthomonas citri subsp. citri type III secretion system, and the cytosolic domain of the inner membrane protein HrcU, a paralog of the flagellar protein FlhB. We show that a recombinant fragment corresponding to the C-terminal cytosolic domain of HrcU produced in E. coli suffers cleavage within a conserved Asn264-Pro265-Thr266-His267 (NPTH) sequence. A recombinant HrcU cytosolic domain with N264A, P265A, T266A mutations at the cleavage site (HrcUAAAH) was not cleaved and interacted with HrpB2. Furthermore, a polypeptide corresponding to the sequence following the NPTH cleavage site also interacted with HrpB2 indicating that the site for interaction is located after the NPTH site. Non-polar deletion mutants of the hrcU and hrpB2 genes resulted in a total loss of pathogenicity in susceptible citrus plants and disease symptoms could be recovered by expression of HrpB2 and HrcU from extrachromossomal plasmids. Complementation of the ΔhrcU mutant with HrcUAAAH produced canker lesions similar to those observed when complemented with wild-type HrcU. HrpB2 secretion however, was significantly reduced in the ΔhrcU mutant complemented with HrcUAAAH, suggesting that an intact and cleavable NPTH site in HrcU is necessary for total functionally of T3SS in X. citri subsp. citri. Complementation of the ΔhrpB2 X. citri subsp. citri strain with a series of hrpB2 gene mutants revealed that the highly conserved HrpB2 C-terminus is essential for T3SS-dependent development of citrus canker symptoms in planta. PMID:21408079

  17. Pathogenic Interactions Between Xanthomonas axonopodis pv. citri and Cultivars of Pummelo (Citrus grandis).

    PubMed

    Shiotani, H; Ozaki, K; Tsuyumu, S

    2000-12-01

    ABSTRACT The aggressiveness of strains of Xanthomonas axonopodis pv. citri on seven Citrus species, including Citrus sinensis (navel orange), C. paradisi (grapefruit), C. unshiu (Satsuma mandarin), C. junos (Yuzu), C. aurantifolia ('Mexican' lime), C. tachibana (Tachibana), and C. grandis (pummelo: 'Otachibana', 'Banpeiyu', and 'Anseikan'), were assessed by comparing lesion expansion and growth in planta, using a prick inoculation method. The existence of two groups distinct in aggressiveness was demonstrated on the pummelo cultivars, whereas the remaining species tested were uniformly susceptible. The two groups of strains were distinct in lesion expansion and growth in planta; however, both caused canker lesions on the 'Otachibana' pummelo. The sensitivity of the bacterial strains to phages Cp1 and Cp2 was associated with differences in aggressiveness. Namely, all the strains sensitive to Cp2 but resistant to Cp1 were aggressive to 'Otachibana', whereas all the strains sensitive to Cp1 but resistant to Cp2 were weakly aggressive. When a repetitive sequence-based polymerase chain reaction amplification was carried out by enterobacterial repetitive intergeneric consensus (ERIC) sequences (ERIC1R and ERIC2) as the primers, these two groups were also distinguishable by the presence or absence of a 1.8-kb DNA fragment among otherwise identical fragments. The 1.8-kb fragment was amplified only from the strains aggressive to C. grandis.

  18. Structure of proline iminopeptidase from Xanthomonas campestris pv. citri: a prototype for the prolyl oligopeptidase family.

    PubMed

    Medrano, F J; Alonso, J; García, J L; Romero, A; Bode, W; Gomis-Rüth, F X

    1998-01-02

    The proline iminopeptidase from Xanthomonas campestris pv. citri is a serine peptidase that catalyses the removal of N-terminal proline residues from peptides with high specificity. We have solved its three-dimensional structure by multiple isomorphous replacement and refined it to a crystallographic R-factor of 19.2% using X-ray data to 2.7 A resolution. The protein is folded into two contiguous domains. The larger domain shows the general topology of the alpha/beta hydrolase fold, with a central eight-stranded beta-sheet flanked by two helices and the 11 N-terminal residues on one side, and by four helices on the other side. The smaller domain is placed on top of the larger domain and essentially consists of six helices. The active site, located at the end of a deep pocket at the interface between both domains, includes a catalytic triad of Ser110, Asp266 and His294. Cys269, located at the bottom of the active site very close to the catalytic triad, presumably accounts for the inhibition by thiol-specific reagents. The overall topology of this iminopeptidase is very similar to that of yeast serine carboxypeptidase. The striking secondary structure similarity to human lymphocytic prolyl oligopeptidase and dipeptidyl peptidase IV makes this proline iminopeptidase structure a suitable model for the three-dimensional structure of other peptidases of this family.

  19. Structure of proline iminopeptidase from Xanthomonas campestris pv. citri: a prototype for the prolyl oligopeptidase family.

    PubMed Central

    Medrano, F J; Alonso, J; García, J L; Romero, A; Bode, W; Gomis-Rüth, F X

    1998-01-01

    The proline iminopeptidase from Xanthomonas campestris pv. citri is a serine peptidase that catalyses the removal of N-terminal proline residues from peptides with high specificity. We have solved its three-dimensional structure by multiple isomorphous replacement and refined it to a crystallographic R-factor of 19.2% using X-ray data to 2.7 A resolution. The protein is folded into two contiguous domains. The larger domain shows the general topology of the alpha/beta hydrolase fold, with a central eight-stranded beta-sheet flanked by two helices and the 11 N-terminal residues on one side, and by four helices on the other side. The smaller domain is placed on top of the larger domain and essentially consists of six helices. The active site, located at the end of a deep pocket at the interface between both domains, includes a catalytic triad of Ser110, Asp266 and His294. Cys269, located at the bottom of the active site very close to the catalytic triad, presumably accounts for the inhibition by thiol-specific reagents. The overall topology of this iminopeptidase is very similar to that of yeast serine carboxypeptidase. The striking secondary structure similarity to human lymphocytic prolyl oligopeptidase and dipeptidyl peptidase IV makes this proline iminopeptidase structure a suitable model for the three-dimensional structure of other peptidases of this family. PMID:9427736

  20. Disease Development and Symptom Expression of Xanthomonas axonopodis pv. citri in Various Citrus Plant Tissues.

    PubMed

    Vernière, C J; Gottwald, T R; Pruvost, O

    2003-07-01

    ABSTRACT Experimental inoculations of Xanthomonas axonopodis pv. citri in different tissues of Tahiti lime and Pineapple sweet orange were conducted monthly under natural conditions on Réunion Island. The interactions between a set of environmental and epidemic variables associated with disease expression and 184 different factor combinations were investigated to determine the parameters needed to explain Asiatic citrus canker (ACC) disease expression. Area under the disease progress curve (AUDPC), inoculation date (Id), fruit and leaf age ratings (FAR and LAR), and number of days during the first 2 weeks postinoculation for which the temperature was less than 14 degrees C (T(min)) or more than 28 degrees C (T(max)) were retained by principal component analysis and canonical correlation analysis as the most meaningful epidemic and environmental variables, respectively. AUDPC as the strongest dependent variable and combinations of the environmental variables as independent variables were used in multiple regression analyses. Tissue age rating at the time of infection was a good predictor for disease resulting from spray inoculation on fruits and leaves and also on fruits following a wound inoculation. Temperature, as expressed by T(min) or T(max), was also a significant factor in determining disease development described by AUDPC. Mature green stems were highly susceptible after wounding, similarly to leaves, but buds and leaf scars expressed the lowest susceptibility. These variations in disease expression according to the tissues will have different impacts on ACC epidemiology.

  1. [Detection system for Xanthomonas axonopodis pv. citri using rolling circle amplification].

    PubMed

    Huang, Guanjun; Yin, Youping; Zhang, Lun; Li, Xiaojiao; Ge, Jianjun; Chen, Hongjun; Wang, Zhongkang

    2008-03-01

    Padlock probe was designed based on the sequence of the unique hypothetic protein gene in complete genome of Xanthomonas axonopodis pv. citri (Xac), and amplification primers ware designed according to the universal linking sequence of padlock probe. Detection system of rolling circle amplification (RCA) was established and optimized. Results show that the system could detect Xac and its DNA specifically, while other plant pathogens and bacteria attached on the surface of citrus leaves could not be detected. This indicates that the detection system had its specificity. The detection sensitivity of RCA was 20 cfu/microL for Xac cells and 10(2) copy/microL for cloned DNA fragment, which was slightly higher than the sensitivity of conventional PCR. Leaf samples collected from orange orchards were detected with both RCA and conventional PCR. The result shows that the Xac positive percentage had no remarkable difference between the two methods (P>0.01). Because the universal linking sequence in padlock probe can use same amplification condition, the new technology and detection system can be used to detect diverse plant pathogens simultaneously in plant quarantine and disease pre-symptom diagnosis.

  2. Xanthomonas axonopodis pv. citri enters the VBNC state after copper treatment and retains its virulence.

    PubMed

    del Campo, Raquel; Russi, Paola; Mara, Pamela; Mara, Héctor; Peyrou, Mercedes; de León, Inés Ponce; Gaggero, Carina

    2009-09-01

    The most severe form of citrus canker disease is caused by Xanthomonas axonopodis pv. citri (Xac) and affects all types of important citrus crops, reducing fruit yield and quality. Copper-based products are routinely used as a standard control measure for citrus canker. In this work we demonstrate that copper treatment induces the viable but nonculturable (VBNC) state in Xac but does not prevent the development of symptoms in susceptible plants. Short-term exposures to different concentrations of copper solutions were assayed to determine which treatment resulted in Xac nonculturability. Treatment of 10(6) mL(-1) Xac cells for 10 min in a 135-muM CuSO(4) solution (equivalent to three times the free soluble copper concentration applied in one field treatment) resulted in nonculturability. However, 16% of cells were viable based on 5-cyano-2,3-ditolyl tetrazolium chloride staining and 1% were capable of producing canker lesions after infiltrating grapefruit plants. If induction of the VBNC state in Xac cells were to occur under field conditions, this would have to be taken into consideration for an effective control of canker disease.

  3. Xanthomonas axonopodis pv. citri uses a plant natriuretic peptide-like protein to modify host homeostasis.

    PubMed

    Gottig, Natalia; Garavaglia, Betiana S; Daurelio, Lucas D; Valentine, Alex; Gehring, Chris; Orellano, Elena G; Ottado, Jorgelina

    2008-11-25

    Plant natriuretic peptides (PNPs) are a class of extracellular, systemically mobile molecules that elicit a number of plant responses important in homeostasis and growth. The bacterial citrus pathogen, Xanthomonas axonopodis pv. citri, also contains a gene encoding a PNP-like protein, XacPNP, that shares significant sequence similarity and identical domain organization with plant PNPs but has no homologues in other bacteria. We have expressed and purified XacPNP and demonstrated that the bacterial protein alters physiological responses including stomatal opening in plants. Although XacPNP is not expressed under standard nutrient rich culture conditions, it is strongly induced under conditions that mimic the nutrient poor intercellular apoplastic environment of leaves, as well as in infected tissue, suggesting that XacPNP transcription can respond to the host environment. To characterize the role of XacPNP during bacterial infection, we constructed a XacPNP deletion mutant. The lesions caused by this mutant were more necrotic than those observed with the wild-type, and bacterial cell death occurred earlier in the mutant. Moreover, when we expressed XacPNP in Xanthomonas axonopodis pv. vesicatoria, the transgenic bacteria caused less necrotic lesions in the host than the wild-type. In conclusion, we present evidence that a plant-like bacterial PNP can enable a plant pathogen to modify host responses to create conditions favorable to its own survival.

  4. The Xanthomonas axonopodis pv. citri flagellum is required for mature biofilm and canker development.

    PubMed

    Malamud, Florencia; Torres, Pablo S; Roeschlin, Roxana; Rigano, Luciano A; Enrique, Ramón; Bonomi, Hernán R; Castagnaro, Atilio P; Marano, María Rosa; Vojnov, Adrián A

    2011-03-01

    Xanthomonas axonopodis pv. citri (Xac) is the causative agent of citrus canker. This bacterium develops a characteristic biofilm on both biotic and abiotic surfaces. To evaluate the participation of the single flagellum of Xac in biofilm formation, mutants in the fliC (flagellin) and the flgE (hook) genes were generated. Swimming motility, assessed on 0.25 % agar plates, was markedly reduced in fliC and flgE mutants. However, the fliC and flgE mutants exhibited a flagellar-independent surface translocation on 0.5 % agar plates. Mutation of either the rpfF or the rpfC gene, which both encode proteins involved in cell-cell signalling mediated by diffusible signal factor (DSF), led to a reduction in both flagellar-dependent and flagellar-independent surface translocation, indicating a regulatory role for DSF in both types of motility. Confocal laser scanning microscopy of biofilms produced in static culture demonstrated that the flagellum is also involved in the formation of mushroom-shaped structures and water channels, and in the dispersion of biofilms. The presence of the flagellum was required for mature biofilm development on lemon leaf surfaces. The absence of flagellin produced a slight reduction in Xac pathogenicity and this reduction was more severe when the complete flagellum structure was absent.

  5. Solution structure of ApaG from Xanthomonas axonopodis pv. citri reveals a fibronectin-3 fold.

    PubMed

    Cicero, Daniel O; Contessa, Gian M; Pertinhez, Thelma A; Gallo, Mariana; Katsuyama, Angela M; Paci, Maurizio; Farah, Chuck S; Spisni, Alberto

    2007-05-01

    ApaG proteins are found in a wide variety of bacterial genomes but their function is as yet unknown. Some eukaryotic proteins involved in protein-protein interactions, such as the human polymerase delta-interacting protein (PDIP38) and the F Box A (FBA) proteins, contain ApaG homology domains. We have used NMR to determine the solution structure of ApaG protein from the plant pathogen Xanthomonas axonopodis pv. citri (ApaG(Xac)) with the aim to shed some light on its molecular function. ApaG(Xac) is characterized by seven antiparallel beta strands forming two beta sheets, one containing three strands (ABE) and the other four strands (GFCC'). Relaxation measurements indicate that the protein has a quite rigid structure. In spite of the presence of a putative GXGXXG pyrophosphate binding motif ApaG(Xac) does not bind ATP or GTP, in vitro. On the other hand, ApaG(Xac) adopts a fibronectin type III (Fn3) fold, which is consistent with the hypothesis that it is involved in mediating protein-protein interactions. The fact that the proteins of ApaG family do not display significant sequence similarity with the Fn3 domains found in other eukaryotic or bacterial proteins suggests that Fn3 domain may have arisen earlier in evolution than previously estimated.

  6. Genomic insights into the evolutionary origin of Xanthomonas axonopodis pv. citri and its ecological relatives.

    PubMed

    Midha, Samriti; Patil, Prabhu B

    2014-10-01

    Xanthomonas axonopodis pv. citri (Xac) is the causal agent of citrus bacterial canker (CBC) and is a serious problem worldwide. Like CBC, several important diseases in other fruits, such as mango, pomegranate, and grape, are also caused by Xanthomonas pathovars that display remarkable specificity toward their hosts. While citrus and mango diseases were documented more than 100 years ago, the pomegranate and grape diseases have been known only since the 1950s and 1970s, respectively. Interestingly, diseases caused by all these pathovars were noted first in India. Our genome-based phylogenetic studies suggest that these diverse pathogens belong to a single species and these pathovars may be just a group of rapidly evolving strains. Furthermore, the recently reported pathovars, such as those infecting grape and pomegranate, form independent clonal lineages, while the citrus and mango pathovars that have been known for a long time form one clonal lineage. Such an understanding of their phylogenomic relationship has further allowed us to understand major and unique variations in the lineages that give rise to these pathovars. Whole-genome sequencing studies including ecological relatives from their putative country of origin has allowed us to understand the evolutionary history of Xac and other pathovars that infect fruits.

  7. Cloning and characterization of three hypothetical secretion chaperone proteins from Xanthomonas axonopodis pv. citri.

    PubMed

    Tasic, Ljubica; Borin, Paula F L; Khater, Leti Cia; Ramos, Carlos H I

    2007-06-01

    Xanthomonas axonopodis pv. citri (Xac) causes citrus canker in plantations around the world and is of particular significance in Brazil where its incidence has risen exponentially over the past decade. Approximately one third of the predicted Xac open reading frames show no homology, or homology with very low score with that of known sequences. It is believed that Xac utilizes secretion systems to transfer virulence proteins into susceptible eukaryotic cells. This process is assisted by secretion chaperones that maintain virulence proteins partly or completely unfolded during translocation. We have cloned three of these hypothetical secretion chaperones: XAC0419 and XAC1346 from type III secretion system (TTSS) and XACb0033 from type IV secretion system (TFSS). All proteins were cloned in a pET23a vector (Novagen), expressed at 37 degrees C using a BL21(DE3)pLysS Escherichia coli strain and purified by ion exchange and gel-filtration chromatographic methods. Pure proteins were characterized using spectroscopic measurements: circular dichroism, and both static and lifetime emission fluorescence in the case of XACb0033. The analyzed proteins are stable at elevated temperatures (up to 65 degrees C) and exhibit alpha-helix content from approximately 30% (XACb003) to approximately 87% (XAC1346). XACb0033 exhibits lifetimes in the fluorescence experiments that indicate different neighborhoods for its tryptophan residues. These chaperones have the characteristics of TTSS and TFSS: all are small, with a high alpha-helix content, and without ATP-binding or ATP-hydrolyzing activity.

  8. The oligopeptide permease (Opp) of the plant pathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Moutran, Alexandre; Quaggio, Ronaldo Bento; Balan, Andrea; Ferreira, Luis Carlos de Souza; Ferreira, Rita de Cássia Café

    2004-05-01

    The oligopeptide permease (Opp), a protein-dependent ABC transporter, has been found in the genome of Xanthomonas axonopodis pv. citri ( Xac), but not in Xanthomonas campestris pv. campestris ( Xcc). Sequence analysis indicated that 4 opp genes ( oppA, oppB, oppC, oppD/F), located in a 33.8-kbp DNA fragment present only in the Xac genome, are arranged in an operon-like structure and share highest sequence similarities with Streptomyces roseofulvus orthologs. Nonetheless, analyses of the GC content, codon usage, and transposon positioning suggested that the Xac opp operon does not have an exogenous origin. The presence of a stop codon at one of the ATP-binding domains of OppD/F would render the uptake system nonfunctional, but detection of a single polycistronic mRNA and periplasmic OppA in actively growing bacteria suggests that the Opp permease is active and could contribute to the distinct nutritional requirements and host specificities of the two Xanthomonas species.

  9. Site-directed gene replacement of the phytopathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Oshiro, Elisa E; Nepomuceno, Roberto S L; Faria, Juarez B; Ferreira, Luís C S; Ferreira, Rita C C

    2006-04-01

    In this work we defined experimental conditions for site-directed gene replacement of the Xanthomonas axonopodis pv. citri (Xac), an economically relevant pathogen of citrus plants. The procedure involved, first, optimizing the electrotransformation conditions of the Xac 306 strain and, second, constructing non-replicative suicide vectors carrying knockout copies of the target gene. Using specific experimental conditions, transformation efficiencies of Xac were at least 100 fold higher than those achieved with electroporation protocols previously designed for X. campestris transformation. Successful gene replacement events were achieved with a suicide vector derived from R6K plasmid (pWR-SS) but not with those with ColE1 replication origin. We have chosen the oppA as a target gene, encoding the binding component (OppA) of the major oligopeptide uptake system found in the genome of the Xac 306 strain, although not in X. campestris pv. campestris (Xcc). Defining the experimental conditions, which allow for the specific mutagenesis of the Xac 306 strain, represents a step in the understanding of both genetics and physiology of this economically important bacterial species.

  10. Mealybugs nested endosymbiosis: going into the ‘matryoshka’ system in Planococcus citri in depth

    PubMed Central

    2013-01-01

    Background In all branches of life there are plenty of symbiotic associations. Insects are particularly well suited to establishing intracellular symbiosis with bacteria, providing them with metabolic capabilities they lack. Essential primary endosymbionts can coexist with facultative secondary symbionts which can, eventually, establish metabolic complementation with the primary endosymbiont, becoming a co-primary. Usually, both endosymbionts maintain their cellular identity. An exception is the endosymbiosis found in mealybugs of the subfamily Pseudoccinae, such as Planococcus citri, with Moranella endobia located inside Tremblaya princeps. Results We report the genome sequencing of M. endobia str. PCVAL and the comparative genomic analyses of the genomes of strains PCVAL and PCIT of both consortium partners. A comprehensive analysis of their functional capabilities and interactions reveals their functional coupling, with many cases of metabolic and informational complementation. Using comparative genomics, we confirm that both genomes have undergone a reductive evolution, although with some unusual genomic features as a consequence of coevolving in an exceptional compartmentalized organization. Conclusions M. endobia seems to be responsible for the biosynthesis of most cellular components and energy provision, and controls most informational processes for the consortium, while T. princeps appears to be a mere factory for amino acid synthesis, and translating proteins, using the precursors provided by M. endobia. In this scenario, we propose that both entities should be considered part of a composite organism whose compartmentalized scheme (somehow) resembles a eukaryotic cell. PMID:23548081

  11. The GC/MS Analysis of Volatile Components Extracted by Different Methods from Exocarpium Citri Grandis.

    PubMed

    Xie, Zhisheng; Liu, Qundi; Liang, Zhikun; Zhao, Mingqian; Yu, Xiaoxue; Yang, Depo; Xu, Xinjun

    2013-01-01

    Volatile components from Exocarpium Citri Grandis (ECG) were, respectively, extracted by three methods, that is, steam distillation (SD), headspace solid-phase microextraction (HS-SPME), and solvent extraction (SE). A total of 81 compounds were identified by gas chromatography-mass spectrometry including 77 (SD), 56 (HS-SPME), and 48 (SE) compounds, respectively. Despite of the extraction method, terpenes (39.98~57.81%) were the main volatile components of ECG, mainly germacrene-D, limonene, 2,6,8,10,14-hexadecapentaene, 2,6,11,15-tetramethyl-, (E,E,E)-, and trans-caryophyllene. Comparison was made among the three methods in terms of extraction profile and property. SD relatively gave an entire profile of volatile in ECG by long-time extraction; SE enabled the analysis of low volatility and high molecular weight compounds but lost some volatiles components; HS-SPME generated satisfactory extraction efficiency and gave similar results to those of SD at analytical level when consuming less sample amount, shorter extraction time, and simpler procedure. Although SD and SE were treated as traditionally preparative extractive techniques for volatiles in both small batches and large scale, HS-SPME coupled with GC/MS could be useful and appropriative for the rapid extraction and qualitative analysis of volatile components from medicinal plants at analytical level.

  12. The GC/MS Analysis of Volatile Components Extracted by Different Methods from Exocarpium Citri Grandis

    PubMed Central

    Liu, Qundi; Liang, Zhikun; Zhao, Mingqian; Yu, Xiaoxue; Yang, Depo; Xu, Xinjun

    2013-01-01

    Volatile components from Exocarpium Citri Grandis (ECG) were, respectively, extracted by three methods, that is, steam distillation (SD), headspace solid-phase microextraction (HS-SPME), and solvent extraction (SE). A total of 81 compounds were identified by gas chromatography-mass spectrometry including 77 (SD), 56 (HS-SPME), and 48 (SE) compounds, respectively. Despite of the extraction method, terpenes (39.98~57.81%) were the main volatile components of ECG, mainly germacrene-D, limonene, 2,6,8,10,14-hexadecapentaene, 2,6,11,15-tetramethyl-, (E,E,E)-, and trans-caryophyllene. Comparison was made among the three methods in terms of extraction profile and property. SD relatively gave an entire profile of volatile in ECG by long-time extraction; SE enabled the analysis of low volatility and high molecular weight compounds but lost some volatiles components; HS-SPME generated satisfactory extraction efficiency and gave similar results to those of SD at analytical level when consuming less sample amount, shorter extraction time, and simpler procedure. Although SD and SE were treated as traditionally preparative extractive techniques for volatiles in both small batches and large scale, HS-SPME coupled with GC/MS could be useful and appropriative for the rapid extraction and qualitative analysis of volatile components from medicinal plants at analytical level. PMID:24349825

  13. Quality Matters: Influences of Citrus Flush Physicochemical Characteristics on Population Dynamics of the Asian Citrus Psyllid (Hemiptera: Liviidae)

    PubMed Central

    Simpson, Catherine R.; Alabi, Olufemi J.; Nelson, Shad D.; Telagamsetty, Srilakshmi; Jifon, John L.

    2016-01-01

    Studies were conducted to relate the influence of the physical characteristics, leaf nutrient content and phloem sap amino acid concentration of citrus flush shoots on the densities of various Diaphorina citri life stages. Adult D. citri preferentially selected young shoots for feeding and numbers of D. citri immatures were positively correlated with flush shoot softness. Young flush shoots had higher concentrations of macro and micro nutrients relative to mature ones and this was associated with higher densities of all D. citri life stages. All D. citri life stages were positively correlated with higher nitrogen-carbon (N:C), nitrogen:sulfur (N:S) and nitrogen:calcium (N:Ca) ratios in leaf tissue, while densities of adults were negatively related to calcium, manganese and boron levels. Concentrations of total and essential amino acids were highest in phloem sap of young expanding flush shoots in both grapefruit and lemon, but dramatically declined as flush shoots matured. The sulfur-containing amino acids cystine, methionine and taurine occurred only in younger flush shoots. In contrast, cystathionine was only present in phloem sap of mature shoots. These results clearly indicate that young citrus flush shoots are a nutritionally richer diet relative to mature shoots, thus explaining their preference by D. citri for feeding and reproduction. Conversely, tissue hardness and the lower nutritional quality of mature flush shoots may limit oviposition and immature development. The data suggest that both physical characteristics and nutritional composition of flush shoots and their phloem sap are important factors regulating host colonization and behavior of D. citri, and this interaction can impact the dynamics and spread of HLB in citrus groves. PMID:28030637

  14. Quality Matters: Influences of Citrus Flush Physicochemical Characteristics on Population Dynamics of the Asian Citrus Psyllid (Hemiptera: Liviidae).

    PubMed

    Sétamou, Mamoudou; Simpson, Catherine R; Alabi, Olufemi J; Nelson, Shad D; Telagamsetty, Srilakshmi; Jifon, John L

    2016-01-01

    Studies were conducted to relate the influence of the physical characteristics, leaf nutrient content and phloem sap amino acid concentration of citrus flush shoots on the densities of various Diaphorina citri life stages. Adult D. citri preferentially selected young shoots for feeding and numbers of D. citri immatures were positively correlated with flush shoot softness. Young flush shoots had higher concentrations of macro and micro nutrients relative to mature ones and this was associated with higher densities of all D. citri life stages. All D. citri life stages were positively correlated with higher nitrogen-carbon (N:C), nitrogen:sulfur (N:S) and nitrogen:calcium (N:Ca) ratios in leaf tissue, while densities of adults were negatively related to calcium, manganese and boron levels. Concentrations of total and essential amino acids were highest in phloem sap of young expanding flush shoots in both grapefruit and lemon, but dramatically declined as flush shoots matured. The sulfur-containing amino acids cystine, methionine and taurine occurred only in younger flush shoots. In contrast, cystathionine was only present in phloem sap of mature shoots. These results clearly indicate that young citrus flush shoots are a nutritionally richer diet relative to mature shoots, thus explaining their preference by D. citri for feeding and reproduction. Conversely, tissue hardness and the lower nutritional quality of mature flush shoots may limit oviposition and immature development. The data suggest that both physical characteristics and nutritional composition of flush shoots and their phloem sap are important factors regulating host colonization and behavior of D. citri, and this interaction can impact the dynamics and spread of HLB in citrus groves.

  15. Sensitive and specific detection of Xanthomonas axonopodis pv. citri by PCR using pathovar specific primers based on hrpW gene sequences.

    PubMed

    Park, Dong Suk; Hyun, Jae Wook; Park, Young Jin; Kim, Jung Sun; Kang, Hee Wan; Hahn, Jang Ho; Go, Seung Joo

    2006-01-01

    A sensitive and specific assay was developed to detect citrus bacterial canker caused by Xanthomonas axonopodis pv. citri, in leaves and fruits of citrus. Primers XACF and XACR from hrpW homologous to pectate lyase, modifying the structure of pectin in plants, were used to amplify a 561 bp DNA fragment. PCR technique was applied to detect the pathogen in naturally or artificially infected leaves of citrus. The PCR product was only produced from X. axonopodis pv. citri among 26 isolates of Xanthomonas strains, Escherichia coli (O157:H7), Pectobacterium carotovorum subsp. carotovorum, and other reference microbes.

  16. A pthA homolog from Xanthomonas axonopodis pv. citri responsible for host-specific suppression of virulence.

    PubMed

    Shiotani, Hiroshi; Fujikawa, Takashi; Ishihara, Hiromichi; Tsuyumu, Sinji; Ozaki, Katsumi

    2007-04-01

    Strains of the plant-pathogenic bacterium Xanthomonas axonopodis pv. citri are differentiated into two groups with respect to aggressiveness (normal and weak) on Citrus grandis cultivars but not on other Citrus species such as Citrus sinensis. Random mutagenesis using the transposon Tn5 in X. axonopodis pv. citri strain KC21, which showed weak aggressiveness on a C. grandis cultivar, was used to isolate mutant KC21T46, which regained a normal level of aggressiveness on the cultivar. The gene inactivated by the transposon, hssB3.0, was shown to be responsible for the suppression of virulence on C. grandis. Sequence analysis revealed it to be a new member of the pthA homologs, which was almost identical in sequence to the other homologs except for the number of tandem repeats in the central region of the gene. hssB3.0 appears to be a chimera of other pthA homologs, pB3.1 and pB3.7, and could have been generated by recombination between these two genes. Importantly, in X. axonopodis pv. citri, hssB3.0 was found in all of the tested isolates belonging to the weakly aggressive group but not in the isolates of the normally aggressive group. Isolation of the virulence-deficient mutant KC21T14 from KC21, in which the pathogenicity gene pthA-KC21 was disrupted, showed that hssB3.0 induces a defense response on the host but partially interrupts canker development elicited by the pathogenicity gene in this bacterium.

  17. Characterization of bacteriophages Cp1 and Cp2, the strain-typing agents for Xanthomonas axonopodis pv. citri.

    PubMed

    Ahmad, Abdelmonim Ali; Ogawa, Megumi; Kawasaki, Takeru; Fujie, Makoto; Yamada, Takashi

    2014-01-01

    The strains of Xanthomonas axonopodis pv. citri, the causative agent of citrus canker, are historically classified based on bacteriophage (phage) sensitivity. Nearly all X. axonopodis pv. citri strains isolated from different regions in Japan are lysed by either phage Cp1 or Cp2; Cp1-sensitive (Cp1(s)) strains have been observed to be resistant to Cp2 (Cp2(r)) and vice versa. In this study, genomic and molecular characterization was performed for the typing agents Cp1 and Cp2. Morphologically, Cp1 belongs to the Siphoviridae. Genomic analysis revealed that its genome comprises 43,870-bp double-stranded DNA (dsDNA), with 10-bp 3'-extruding cohesive ends, and contains 48 open reading frames. The genomic organization was similar to that of Xanthomonas phage phiL7, but it lacked a group I intron in the DNA polymerase gene. Cp2 resembles morphologically Escherichia coli T7-like phages of Podoviridae. The 42,963-bp linear dsDNA genome of Cp2 contained terminal repeats. The Cp2 genomic sequence has 40 open reading frames, many of which did not show detectable homologs in the current databases. By proteomic analysis, a gene cluster encoding structural proteins corresponding to the class III module of T7-like phages was identified on the Cp2 genome. Therefore, Cp1 and Cp2 were found to belong to completely different virus groups. In addition, we found that Cp1 and Cp2 use different molecules on the host cell surface as phage receptors and that host selection of X. axonopodis pv. citri strains by Cp1 and Cp2 is not determined at the initial stage by binding to receptors.

  18. Multiplexed lateral flow microarray assay for detection of citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis pv citri

    SciTech Connect

    Cary,; Bruce, R; Stubben, Christopher J

    2011-03-22

    The invention provides highly sensitive and specific assays for the major citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis, including a field deployable multiplexed assay capable of rapidly assaying for both pathogens simultaneously. The assays are directed at particular gene targets derived from pathogenic strains that specifically cause the major citrus diseases of citrus variegated chlorosis (Xylella fastidiosa 9a5c) and citrus canker (Xanthomonas axonopodis pv citri). The citrus pathogen assays of the invention offer femtomole sensitivity, excellent linear dynamic range, and rapid and specific detection.

  19. Expression, purification, and characterization of an aminopeptidase (Xac2987) with broad specificity from Xanthomonas axonopodis pv. citri.

    PubMed

    Santos, Kelly; Medrano, Francisco J

    2007-03-01

    We report here, the cloning, expression, and purification of a broad specificity aminopeptidase from Xanthomonas campestris pv. citri in fusion with a hexa-histidine tag at the N-terminal portion of the protein to facilitate purification. The protein was expressed in the soluble fraction and could be purified in one step by IMAC, yielding approximately 50mg pure protein per liter of cells. We show that the protein is folded and presents aminopeptidase activity against synthetic substrates. Also, we present the characterization of its specificity, showing that the protein was, indeed, able to catalyze the removal of N-terminal residues from synthetic substrates.

  20. Crystallization, data collection and phasing of the molybdate-binding protein of the phytopathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Santacruz, C P; Balan, A; Ferreira, L C S; Barbosa, J A R G

    2006-03-01

    Xanthomonas axonopodis pv. citri ModA protein is the ABC periplasmic binding component responsible for the capture of molybdate. The protein was crystallized with sodium molybdate using the hanging-drop vapour-diffusion method in the presence of PEG or sulfate. X-ray diffraction data were collected to a maximum resolution of 1.7 A using synchrotron radiation. The crystal belongs to the orthorhombic space group C222(1), with unit-cell parameters a = 68.15, b = 172.14, c = 112.04 A. The crystal structure was solved by molecular-replacement methods and structure refinement is in progress.

  1. Structural-functional characterization and physiological significance of ferredoxin-NADP reductase from Xanthomonas axonopodis pv. citri.

    PubMed

    Tondo, María Laura; Musumeci, Matías A; Delprato, María Laura; Ceccarelli, Eduardo A; Orellano, Elena G

    2011-01-01

    Xanthomonas axonopodis pv. citri is a phytopathogen bacterium that causes severe citrus canker disease. Similar to other phytopathogens, after infection by this bacterium, plants trigger a defense mechanism that produces reactive oxygen species. Ferredoxin-NADP(+) reductases (FNRs) are redox flavoenzymes that participate in several metabolic functions, including the response to reactive oxygen species. Xanthomonas axonopodis pv. citri has a gene (fpr) that encodes for a FNR (Xac-FNR) that belongs to the subclass I bacterial FNRs. The aim of this work was to search for the physiological role of this enzyme and to characterize its structural and functional properties. The functionality of Xac-FNR was tested by cross-complementation of a FNR knockout Escherichia coli strain, which exhibit high susceptibility to agents that produce an abnormal accumulation of (•)O(2)(-). Xac-FNR was able to substitute for the FNR in E. coli in its antioxidant role. The expression of fpr in X. axonopodis pv. citri was assessed using semiquantitative RT-PCR and Western blot analysis. A 2.2-fold induction was observed in the presence of the superoxide-generating agents methyl viologen and 2,3-dimethoxy-1,4-naphthoquinone. Structural and functional studies showed that Xac-FNR displayed different functional features from other subclass I bacterial FNRs. Our analyses suggest that these differences may be due to the unusual carboxy-terminal region. We propose a further classification of subclass I bacterial FNRs, which is useful to determine the nature of their ferredoxin redox partners. Using sequence analysis, we identified a ferredoxin (XAC1762) as a potential substrate of Xac-FNR. The purified ferredoxin protein displayed the typical broad UV-visible spectrum of [4Fe-4S] clusters and was able to function as substrate of Xac-FNR in the cytochrome c reductase activity. Our results suggest that Xac-FNR is involved in the oxidative stress response of Xanthomonas axonopodis pv. citri and

  2. Characterization of three linalool synthase genes from Citrus unshiu Marc. and analysis of linalool-mediated resistance against Xanthomonas citri subsp. citri and Penicilium italicum in citrus leaves and fruits.

    PubMed

    Shimada, Takehiko; Endo, Tomoko; Fujii, Hiroshi; Rodríguez, Ana; Peña, Leandro; Omura, Mitsuo

    2014-12-01

    Three cDNA clones from Satsuma mandarin (Citrus unshiu Marc.) were isolated and expressed in Escherichia coli. CuSTS3-1 and CuSTS3-2 encode linalool synthases and CuSTS4 encodes a nerolidol/linalool synthase. Transcripts of CuSTS3-1, CuSTS3-2 and CuSTS4 were abundant in young fruit at 60 days after flowering (DAF), flowers and leaves, respectively. Treatments with Xanthomonas citri subsp. citri (XCC), the causal agent of citrus canker and Penicillium italicum (PI), the cause of post-harvest fruit decay, and wounding up-regulated CuSTS3-1 in fruit and mainly CuSTS4 in leaves. Linalool, citral, geraniol and citronellol showed strong antibacterial and antifungal activities against XCC and PI in vitro, while most other mono-and sesquiterpenes, including limonene and gamma-terpinene, did not. Linalool, used at levels similar to those present in resistant Ponkan mandarin (Citrus reticulata Blanco) leaves, was able to inhibit growth of XCC in vitro. Compared to other five citrus types, linalool accumulated at extraordinarily high levels in Ponkan mandarin leaves and was released at high amounts from their leaves, while it was hardly detectable in the most susceptible species, indicating that linalool biosynthesis and accumulation might be involved in plant defense against bacterial and fungal pathogens and be associated with field resistance to citrus canker.

  3. Contribution of a harpin protein from Xanthomonas axonopodis pv. citri to pathogen virulence.

    PubMed

    Sgro, Germán G; Ficarra, Florencia A; Dunger, Germán; Scarpeci, Telma E; Valle, Estela M; Cortadi, Adriana; Orellano, Elena G; Gottig, Natalia; Ottado, Jorgelina

    2012-12-01

    Xanthomonas axonopodis pv. citri (Xac), the bacterium that causes citrus canker, contains a gene in the hrp [for hypersensitive response (HR) and pathogenicity] cluster that encodes a harpin protein called Hpa1. Hpa1 produced HR in the nonhost plants tobacco, pepper and Arabidopsis, whereas, in the host plant citrus, it elicited a weak defence response with no visible phenotype. Co-infiltrations of Xac with or without the recombinant Hpa1 protein in citrus leaves produced a larger number of cankers in the presence of the protein. To characterize the effect of Hpa1 during the disease, an XacΔhpa1 mutant was constructed, and infiltration of this mutant caused a smaller number of cankers. In addition, the lack of Hpa1 hindered bacterial aggregation both in solution and in planta. Analysis of citrus leaves infiltrated with Hpa1 revealed alterations in mesophyll morphology caused by the presence of cavitations and crystal idioblasts, suggesting the binding of the harpin to plant membranes and the elicitation of signalling cascades. Overall, these results suggest that, even though Hpa1 elicits the defence response in nonhost plants and, to a lesser extent, in host plants, its main roles in citrus canker are to alter leaf mesophyll structure and to aggregate bacterial cells, and thus increase virulence and pathogen fitness. We expressed the N-terminal and C-terminal regions and found that, although both regions elicited HR in nonhost plants, only the N-terminal region showed increased virulence and bacterial aggregation, supporting the role of this region of the protein as the main active domain.

  4. Amplification of DNA of Xanthomonas axonopodis pv. citri from historic citrus canker herbarium specimens.

    PubMed

    Li, Wenbin; Brlansky, Ronald H; Hartung, John S

    2006-05-01

    Herbaria are important resources for the study of the origins and dispersal of plant pathogens, particularly bacterial plant pathogens that incite local lesions in which large numbers of pathogen genomes are concentrated. Xanthomonas axonopodis pv. citri (Xac), the causal agent of citrus bacterial canker disease, is a notable example of such a pathogen. The appearance of novel strains of the pathogen in Florida and elsewhere make it increasingly important to understand the relationships among strains of this pathogen. USDA-ARS at Beltsville, Maryland maintains approximately 700 herbarium specimens with citrus canker disease lesions up to 90 years old, originally collected from all over the world, and so is an important resource for phytogeographic studies of this bacterium. Unfortunately, DNA in herbarium specimens is degraded and may contain high levels of inhibitors of PCR. In this study, we compared a total of 23 DNA isolation techniques in combination with 31 novel primer pairs in order to develop an efficient protocol for the analysis of Xac DNA in herbarium specimens. We identified the most reliable extraction method, identified in terms of successful amplification by our panel of 31 primer pairs. We also identified the most robust primer pairs, identified as successful in the largest number of extracts prepared by different methods. We amplified Xac genomic sequences up to 542 bp long from herbarium samples up to 89 years old. Primers varied in effectiveness, with some primer pairs amplifying Xac DNA from a 1/10,000 dilution of extract from a single lesion from a citrus canker herbarium specimen. Our methodology will be useful to identify pathogens and perform molecular analyses of bacterial and possibly fungal genomes from herbarium specimens.

  5. The solution structure of the outer membrane lipoprotein OmlA from Xanthomonas axonopodis pv. citri reveals a protein fold implicated in protein-protein interaction.

    PubMed

    Vanini, Marina Marques Teixeira; Spisni, Alberto; Sforça, Maurício Luis; Pertinhez, Thelma Aguiar; Benedetti, Celso Eduardo

    2008-06-01

    The outer membrane lipoprotein A (OmlA) belongs to a family of bacterial small lipoproteins widely distributed across the beta and gamma proteobacteria. Although the role of numerous bacterial lipoproteins is known, the biological function of OmlA remains elusive. We found that in the citrus canker pathogen, Xanthomonas axonopodis pv. citri (X. citri), OmlA is coregulated with the ferric uptake regulator (Fur) and their expression is enhanced when X. citri is grown on citrus leaves, suggesting that these proteins are involved in plant-pathogen interaction. To gain insights into the function of OmlA, its conformational and dynamic features were determined by nuclear magnetic resonance. The protein has highly flexible N- and C- termini and a structurally well defined core composed of three beta-strands and two small alpha-helices, which pack against each other forming a two-layer alpha/beta scaffold. This protein fold resembles the domains of the beta-lactamase inhibitory protein BLIP, involved in protein-protein binding. In conclusion, the structure of OmlA does suggest that this protein may be implicated in protein-protein interactions required during X. citri infection.

  6. Foraging on and consumption of two species of papaya pest mites, Tetranychus kanzawai and Panonychus citri (Acari: tetranychidae) by Mallada basalis (Neuroptera: Chrysopidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tetranychus kanzawai Kishida and Panonychus citri (McGregor) are two major acarine pests of the principal papaya variety in Taiwan, and they often co-occur in the same papaya screenhouses. This study measured prey acceptability, foraging schedule, short-term consumption rate, and handling time of la...

  7. Differential expression of pathogenicity- and virulence-related genes of Xanthomonas axonopodis pv. citri under copper stress.

    PubMed

    Palmieri, Ana Carolina Basílio; do Amaral, Alexandre Morais; Homem, Rafael Augusto; Machado, Marcos Antonio

    2010-04-01

    In this study, we used real-time quantitative PCR (RT-qPCR) to evaluate the expression of 32 genes of Xanthomonas axonopodis pv. citri related to pathogenicity and virulence that are also involved in copper detoxification. Nearly all of the genes were up-regulated, including copA and copB. Two genes homologous to members of the type II secretion system (xcsH and xcsC) and two involved in the degradation of plant cell wall components (pglA and pel) were the most expressed in response to an elevated copper concentration. The type II secretion system (xcs operon) and a few homologues of proteins putatively secreted by this system showed enhanced expression when the bacteria were exposed to a high concentration of copper sulfate. The enhanced expression of the genes of secretion II system during copper stress suggests that this pathway may have an important role in the adaptative response of X. axonopodis pv. citri to toxic compounds. These findings highlight the potential role of these genes in attenuating the toxicity of certain metals and could represent an important means of bacterial resistance against chemicals used to control diseases.

  8. Crystallization, data collection and phasing of the molybdate-binding protein of the phytopathogen Xanthomonas axonopodis pv. citri

    SciTech Connect

    Santacruz, C. P.; Balan, A.; Ferreira, L. C. S.; Barbosa, J. A. R. G.

    2006-03-01

    The molybdate-binding protein (ModA) from X. axonopodis pv. citri was crystallized with sodium molybdate in the presence of PEG or sulfate. The crystal diffracted to a maximum resolution of 1.7 Å and belongs to the orthorhombic space group C222{sub 1,} with unit-cell parameters a = 68.15, b = 172.14, c = 112.04 Å. Xanthomonas axonopodis pv. citri ModA protein is the ABC periplasmic binding component responsible for the capture of molybdate. The protein was crystallized with sodium molybdate using the hanging-drop vapour-diffusion method in the presence of PEG or sulfate. X-ray diffraction data were collected to a maximum resolution of 1.7 Å using synchrotron radiation. The crystal belongs to the orthorhombic space group C222{sub 1}, with unit-cell parameters a = 68.15, b = 172.14, c = 112.04 Å. The crystal structure was solved by molecular-replacement methods and structure refinement is in progress.

  9. Crystallographic structure and substrate-binding interactions of the molybdate-binding protein of the phytopathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Balan, Andrea; Santacruz-Pérez, Carolina; Moutran, Alexandre; Ferreira, Luís Carlos Souza; Neshich, Goran; Gonçalves Barbosa, João Alexandre Ribeiro

    2008-02-01

    In Xanthomonas axonopodis pv. citri (Xac or X. citri), the modA gene codes for a periplasmic protein (ModA) that is capable of binding molybdate and tungstate as part of the ABC-type transporter required for the uptake of micronutrients. In this study, we report the crystallographic structure of the Xac ModA protein with bound molybdate. The Xac ModA structure is similar to orthologs with known three-dimensional structures and consists of two nearly symmetrical domains separated by a hinge region where the oxyanion-binding site lies. Phylogenetic analysis of different ModA orthologs based on sequence alignments revealed three groups of molybdate-binding proteins: bacterial phytopathogens, enterobacteria and soil bacteria. Even though the ModA orthologs are segregated into different groups, the ligand-binding hydrogen bonds are mostly conserved, except for Archaeglobus fulgidus ModA. A detailed discussion of hydrophobic interactions in the active site is presented and two new residues, Ala38 and Ser151, are shown to be part of the ligand-binding pocket.

  10. Murraya paniculata (orange jasmine), a host and possible inoculum reservoir for Candidatus Liberibacter asiaticus, causal agent of Huanglongbing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB), considered the most serious vectored-pathogen of citrus, is transmitted in nature by the Asian citrus psyllid Diaphorina citri and the African citrus psyllid Trioza erytreae. In 1999, D. citri was discovered in southern Florida and has become established in FL and TX. Huanglon...

  11. Metabolic interplay between the Asian citrus psyllid and its Profftella symbiont: An Achilles’ heel of the citrus greening insect vector

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ‘Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease, is transmitted by Diaphorina citri, the Asian citrus psyllid. Interactions among D. citri and its microbial endosymbionts, including ‘Candidatus Profftella armatura’, are likely to impact tra...

  12. Localized autoinoculation and dissemination of Isaria fumosorosea for control of the Asian citrus psyllid in South Texas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri Kuwayama, vectors the causal organism of citrus greening disease. Integrated strategies are needed to control D. citri in south Texas. Control approaches involving entomopathogenic fungi may be useful on ornamental and abandoned citrus and other rutaceous...

  13. A plasmid from S. citri strain M14 hybridizes with extrachromosomal DNAs from other spiroplasmas, including corn stunt spiroplasma E275, tick spiroplasma 277F, and coco spiroplasma N525.

    PubMed Central

    Mouches, C.; Bové, J. M.

    1983-01-01

    A plasmid, pM41, has been isolated from the Spiroplasma citri strain M4 (group I-1) and characterized by restriction mapping. Using a 32P-labeled probe specific of the plasmid, we have shown by DNA-DNA hybridization that a plasmid identical to pM41 or a closely related plasmid, is present in several, but not all, S. citri strains. DNA sequences that hybridize to pM41 were also identified in three other spiroplasmas not belonging to the S. citri species. Protein patterns of several S. citri strains have been compared in order to investigate the effect of pM41 on the spiroplasma protein profiles or maps. In fact, the presence of pM41 does not appear to modify the protein pattern. Images FIG. 1 PMID:6679153

  14. Expression, purification, crystallization and preliminary X-ray analysis of YaeQ (XAC2396) from Xanthomonas axonopodis pv. citri.

    PubMed

    Guzzo, Cristiane R; Nagem, Ronaldo A P; Galvão-Botton, Leonor M P; Guimarães, Beatriz G; Medrano, Francisco J; Barbosa, João A R G; Farah, Chuck S

    2005-05-01

    Xanthomonas axonopodis pv. citri YaeQ (XAC2396) is a member of a family of bacterial proteins conserved in several Gram-negative pathogens. Here, the cloning, expression, purification and crystallization of the 182-residue (20.6 kDa) YaeQ protein are described. Recombinant YaeQ containing selenomethionine was crystallized in space group P2(1) and crystals diffracted to 1.9 A resolution at a synchrotron source. The unit-cell parameters are a = 39.75, b = 91.88, c = 48.03 A, beta = 108.37 degrees. The calculated Matthews coefficient suggests the presence of two YaeQ molecules in the asymmetric unit. Initial experimental phases were calculated by the multiple-wavelength anomalous dispersion technique and an interpretable electron-density map was obtained.

  15. Phenylacetaldehyde O-methyloxime: a volatile compound produced by grapefruit leaves infected with the citrus canker pathogen, Xanthomonas axonopodis pv. citri.

    PubMed

    Zhang, Aijun; Hartung, John S

    2005-06-29

    An aldehyde oxime O-methyl ether, phenylacetaldehyde O-methyloxime, was detected using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) in the headspace above grapefruit leaves infected with Xanthomonas axonopodis pv. citri, the causal agent of citrus bacterial canker disease (CBCD). This disease is a major phytosanitary concern, and an eradication campaign against it is currently underway in Florida. Phenylacetaldehyde O-methyloxime has been reported to be produced by other plants and fragrant flowers, but it was not observed in the headspace above uninfected grapefruit leaves, the pathogenic bacterium X. axonopodis pv. citri itself, or grapefruit leaves infected with another closely related bacterial pathogen, X. axonopodis pv. citrumelo, which causes citrus bacterial spot, a disease of no phytosanitary significance. It was also not detected from CBCD infected fruits, including orange, lemon, grapefruit, and lime. We conclude that phenylacetaldehyde O-methyloxime may potentially be used to identify CBCD infestations. However, more intensive studies will be required to fully evaluate the potential of phenylacetaldehyde O-methyloxime as a diagnostic compound for CBCD. Using SPME and GC-MS to measure phenylacetaldehyde O-methyloxime may provide an easy and feasible tool to complement current methods used to detect X. axonopodis pv. citri in environmental samples.

  16. Diel periodicity of pheromone release by females of Planococcus citri and Planococcus ficus and the temporal flight activity of their conspecific males

    NASA Astrophysics Data System (ADS)

    Levi-Zada, Anat; Fefer, Daniela; David, Maayan; Eliyahu, Miriam; Franco, José Carlos; Protasov, Alex; Dunkelblum, Ezra; Mendel, Zvi

    2014-08-01

    The diel periodicity of sex pheromone release was monitored in two mealybug species, Planococcus citri and Planococcus ficus (Hemiptera; Pseudococcidae), using sequential SPME/GCMS analysis. A maximal release of 2 ng/h pheromone by 9-12-day-old P. citri females occurred 1-2 h before the beginning of photophase. The highest release of pheromone by P. ficus females was 1-2 ng/2 h of 10-20-day-old females, approximately 2 h after the beginning of photophase. Mating resulted in termination of the pheromone release in both mealybug species. The temporal flight activity of the males was monitored in rearing chambers using pheromone baited delta traps. Males of both P. citri and P. ficus displayed the same flight pattern and began flying at 06:00 hours when the light was turned on, reaching a peak during the first and second hour of the photophase. Our results suggest that other biparental mealybug species display also diel periodicities of maximal pheromone release and response. Direct evaluation of the diel periodicity of the pheromone release by the automatic sequential analysis is convenient and will be very helpful in optimizing the airborne collection and identification of other unknown mealybug pheromones and to study the calling behavior of females. Considering this behavior pattern may help to develop more effective pheromone-based management strategies against mealybugs.

  17. Diel periodicity of pheromone release by females of Planococcus citri and Planococcus ficus and the temporal flight activity of their conspecific males.

    PubMed

    Levi-Zada, Anat; Fefer, Daniela; David, Maayan; Eliyahu, Miriam; Franco, José Carlos; Protasov, Alex; Dunkelblum, Ezra; Mendel, Zvi

    2014-08-01

    The diel periodicity of sex pheromone release was monitored in two mealybug species, Planococcus citri and Planococcus ficus (Hemiptera; Pseudococcidae), using sequential SPME/GCMS analysis. A maximal release of 2 ng/h pheromone by 9-12-day-old P. citri females occurred 1-2 h before the beginning of photophase. The highest release of pheromone by P. ficus females was 1-2 ng/2 h of 10-20-day-old females, approximately 2 h after the beginning of photophase. Mating resulted in termination of the pheromone release in both mealybug species. The temporal flight activity of the males was monitored in rearing chambers using pheromone baited delta traps. Males of both P. citri and P. ficus displayed the same flight pattern and began flying at 06:00 hours when the light was turned on, reaching a peak during the first and second hour of the photophase. Our results suggest that other biparental mealybug species display also diel periodicities of maximal pheromone release and response. Direct evaluation of the diel periodicity of the pheromone release by the automatic sequential analysis is convenient and will be very helpful in optimizing the airborne collection and identification of other unknown mealybug pheromones and to study the calling behavior of females. Considering this behavior pattern may help to develop more effective pheromone-based management strategies against mealybugs.

  18. Sclerenchymatous ring as a barrier to phloem feeding by Asian citrus psyllid: Evidence from electrical penetration graph and visualization of stylet pathways

    PubMed Central

    George, Justin; Ammar, El-Desouky; Hall, David G.

    2017-01-01

    Asian citrus psyllid (Diaphorina citri) feeding behaviors play a significant role in the transmission of the phloem-limited Candidatus Liberibacter asiaticus (CLas) bacterium that causes the economically devastating citrus greening disease. Sustained phloem ingestion by D. citri on CLas infected plants is required for pathogen acquisition and transmission. Recent studies have shown a fibrous ring of thick-walled sclerenchyma around the phloem in mature, fully expanded citrus leaves that is more prominent on the abaxial compared with the adaxial side. The composition and thickness of this fibrous ring may have an important role in selection of feeding sites by D. citri based on leaf age and leaf surface, which in turn can affect pathogen acquisition and transmission. We measured feeding behavior using electrical penetration graph (EPG) recordings of individual D. citri adults placed on abaxial or adaxial surfaces of young or mature Valencia orange leaves to study the role of the sclerenchymatous ring in modifying D. citri feeding behavior. Feeding sites on the same leaf tissues were then sectioned and examined by epifluorescence microscopy. The duration of phloem ingestion (E2 waveform) by psyllids was significantly reduced on mature compared with young leaves, and on abaxial compared with adaxial leaf surfaces. The longest duration of phloem ingestion was observed from psyllids placed on the adaxial side of young leaves that had the least developed sclerenchyma. Bouts of phloem salivation (E1 waveform), however, were significantly longer on mature leaves compared with young leaves. D. citri adults made consecutive phloem feeding attempts (bouts) on the abaxial side of mature leaves and those bouts resulted in unsuccessful or shorter periods of phloem ingestion. Adults also made more frequent and longer bouts of xylem ingestion on mature leaves compared with adult psyllids placed on young leaves. Epifluorescence microscopy showed that the fibrous ring in young

  19. Induced release of a plant-defense volatile 'deceptively' attracts insect vectors to plants infected with a bacterial pathogen.

    PubMed

    Mann, Rajinder S; Ali, Jared G; Hermann, Sara L; Tiwari, Siddharth; Pelz-Stelinski, Kirsten S; Alborn, Hans T; Stelinski, Lukasz L

    2012-01-01

    Transmission of plant pathogens by insect vectors is a complex biological process involving interactions between the plant, insect, and pathogen. Pathogen-induced plant responses can include changes in volatile and nonvolatile secondary metabolites as well as major plant nutrients. Experiments were conducted to understand how a plant pathogenic bacterium, Candidatus Liberibacter asiaticus (Las), affects host preference behavior of its psyllid (Diaphorina citri Kuwayama) vector. D. citri were attracted to volatiles from pathogen-infected plants more than to those from non-infected counterparts. Las-infected plants were more attractive to D. citri adults than non-infected plants initially; however after feeding, psyllids subsequently dispersed to non-infected rather than infected plants as their preferred settling point. Experiments with Las-infected and non-infected plants under complete darkness yielded similar results to those recorded under light. The behavior of psyllids in response to infected versus non-infected plants was not influenced by whether or not they were carriers of the pathogen. Quantification of volatile release from non-infected and infected plants supported the hypothesis that odorants mediate psyllid preference. Significantly more methyl salicylate, yet less methyl anthranilate and D-limonene, was released by infected than non-infected plants. Methyl salicylate was attractive to psyllids, while methyl anthranilate did not affect their behavior. Feeding on citrus by D. citri adults also induced release of methyl salicylate, suggesting that it may be a cue revealing location of conspecifics on host plants. Infected plants were characterized by lower levels of nitrogen, phosphorus, sulfur, zinc, and iron, as well as, higher levels of potassium and boron than non-infected plants. Collectively, our results suggest that host selection behavior of D. citri may be modified by bacterial infection of plants, which alters release of specific headspace

  20. Induced Release of a Plant-Defense Volatile ‘Deceptively’ Attracts Insect Vectors to Plants Infected with a Bacterial Pathogen

    PubMed Central

    Mann, Rajinder S.; Ali, Jared G.; Hermann, Sara L.; Tiwari, Siddharth; Pelz-Stelinski, Kirsten S.; Alborn, Hans T.; Stelinski, Lukasz L.

    2012-01-01

    Transmission of plant pathogens by insect vectors is a complex biological process involving interactions between the plant, insect, and pathogen. Pathogen-induced plant responses can include changes in volatile and nonvolatile secondary metabolites as well as major plant nutrients. Experiments were conducted to understand how a plant pathogenic bacterium, Candidatus Liberibacter asiaticus (Las), affects host preference behavior of its psyllid (Diaphorina citri Kuwayama) vector. D. citri were attracted to volatiles from pathogen-infected plants more than to those from non-infected counterparts. Las-infected plants were more attractive to D. citri adults than non-infected plants initially; however after feeding, psyllids subsequently dispersed to non-infected rather than infected plants as their preferred settling point. Experiments with Las-infected and non-infected plants under complete darkness yielded similar results to those recorded under light. The behavior of psyllids in response to infected versus non-infected plants was not influenced by whether or not they were carriers of the pathogen. Quantification of volatile release from non-infected and infected plants supported the hypothesis that odorants mediate psyllid preference. Significantly more methyl salicylate, yet less methyl anthranilate and D-limonene, was released by infected than non-infected plants. Methyl salicylate was attractive to psyllids, while methyl anthranilate did not affect their behavior. Feeding on citrus by D. citri adults also induced release of methyl salicylate, suggesting that it may be a cue revealing location of conspecifics on host plants. Infected plants were characterized by lower levels of nitrogen, phosphorus, sulfur, zinc, and iron, as well as, higher levels of potassium and boron than non-infected plants. Collectively, our results suggest that host selection behavior of D. citri may be modified by bacterial infection of plants, which alters release of specific headspace

  1. Expression, crystallization and preliminary crystallographic analysis of PilZ(XAC1133) from Xanthomonas axonopodis pv. citri.

    PubMed

    Guzzo, Cristiane R; Farah, Chuck S

    2009-03-01

    Proteins containing PilZ domains are widespread in Gram-negative bacteria and have recently been shown to be involved in the control of biofilm formation, adherence, aggregation, virulence-factor production and motility. Furthermore, some PilZ domains have recently been shown to bind the second messenger bis(3'-->5')cyclic diGMP. Here, the cloning, expression, purification and crystallization of PilZ(XAC1133), a protein consisting of a single PilZ domain from Xanthomonas axonopodis pv. citri, is reported. The closest PilZ(XAC1133) homologues in Pseudomonas aeruginosa and Neisseria meningitidis control type IV pilus function. Recombinant PilZ(XAC1133) containing selenomethionine was crystallized in space group P6(1). The unit-cell parameters were a = 62.125, b = 62.125, c = 83.543 A. These crystals diffracted to 1.85 A resolution and a MAD data set was collected at a synchrotron source. The calculated Matthews coefficient suggested the presence of two PilZ(XAC1133) molecules in the asymmetric unit.

  2. Expression, crystallization and preliminary crystallographic analysis of SufE (XAC2355) from Xanthomonas axonopodis pv. citri.

    PubMed

    Guzzo, Cristiane R; Silva, Lucicleide R; Galvão-Botton, Leonor M P; Barbosa, João A R G; Farah, Chuck S

    2006-03-01

    Xanthomonas axonopodis pv. citri (Xac) SufE (XAC2355) is a member of a family of bacterial proteins that are conserved in several pathogens and phytopathogens. The Escherichia coli suf operon is involved in iron-sulfur cluster biosynthesis under iron-limitation and stress conditions. It has recently been demonstrated that SufE and SufS form a novel two-component cysteine desulfarase in which SufS catalyses the conversion of L-cysteine to L-alanine, forming a protein-bound persulfide intermediate. The S atom is then transferred to SufE, from which it is subsequently transferred to target molecules or reduced to sulfide in solution. Here, the cloning, expression, crystallization and phase determination of Xac SufE crystals are described. Recombinant SufE was crystallized in space group P2(1)2(1)2(1) and diffracted to 1.9 A resolution at a synchrotron source. The unit-cell parameters are a = 45.837, b = 58.507, c = 98.951 A, alpha = beta = gamma = 90 degrees. The calculated Matthews coefficient indicated the presence of two molecules in the asymmetric unit. Phasing was performed by molecular-replacement using E. coli SufE as a model (PDB code 1mzg) and an interpretable map was obtained.

  3. Differentially expressed proteins in the interaction of Xanthomonas axonopodis pv. citri with leaf extract of the host plant.

    PubMed

    Mehta, A; Rosato, Y B

    2001-09-01

    The present study reports the expression of proteins of Xanthomonas axonopodis pv. citri in response to different growth conditions. The bacterium was cultured in the basal medium MM1 and in the presence of leaf extracts from a susceptible host plant (sweet orange) as well as a resistant (ponkan) and a nonhost plant (passion fruit). The protein profiles were analyzed by two-dimensional gel electrophoresis (2-DE). Twelve differential spots (induced, up- and down-regulated and repressed) were observed in the protein profiles of the bacterium cultivated in citrus extract (susceptible host) when compared to that of MM1. The 2-DE profile of the bacterium cultured in the complex medium nutrient yeast glycerol was also obtained and the comparison with that of MM1 revealed 36 differential spots. Five proteins from the different treatments were successfully N-terminally sequenced and the putative functions were assigned by homology searches in databases. Two constitutively expressed proteins, B4 and B5, were identified as pseudouridine synthase and elongation factor P, respectively. The large subunit of ribulose 1,5-biphosphate carboxylase/oxygenase and a sulfate binding protein were found as specifically up-regulated in the presence of citrus extracts. Finally, the heat shock protein G was found exclusively in the complex medium and repressed in all other media.

  4. Analysis of three Xanthomonas axonopodis pv. citri effector proteins in pathogenicity and their interactions with host plant proteins.

    PubMed

    Dunger, Germán; Garofalo, Cecilia G; Gottig, Natalia; Garavaglia, Betiana S; Rosa, María C Pereda; Farah, Chuck S; Orellano, Elena G; Ottado, Jorgelina

    2012-10-01

    Xanthomonas axonopodis pv. citri, the bacterium responsible for citrus canker, uses effector proteins secreted by a type III protein secretion system to colonize its hosts. Among the putative effector proteins identified for this bacterium, we focused on the analysis of the roles of AvrXacE1, AvrXacE2 and Xac3090 in pathogenicity and their interactions with host plant proteins. Bacterial deletion mutants in avrXacE1, avrXacE2 and xac3090 were constructed and evaluated in pathogenicity assays. The avrXacE1 and avrXacE2 mutants presented lesions with larger necrotic areas relative to the wild-type strain when infiltrated in citrus leaves. Yeast two-hybrid studies were used to identify several plant proteins likely to interact with AvrXacE1, AvrXacE2 and Xac3090. We also assessed the localization of these effector proteins fused to green fluorescent protein in the plant cell, and observed that they co-localized to the subcellular spaces in which the plant proteins with which they interacted were predicted to be confined. Our results suggest that, although AvrXacE1 localizes to the plant cell nucleus, where it interacts with transcription factors and DNA-binding proteins, AvrXacE2 appears to be involved in lesion-stimulating disease 1-mediated cell death, and Xac3090 is directed to the chloroplast where its function remains to be clarified.

  5. Construction of EGFP-labeling system for visualizing the infection process of Xanthomonas axonopodis pv. citri in planta.

    PubMed

    Liu, Li-Ping; Deng, Zi-Niu; Qu, Jin-Wang; Yan, Jia-Wen; Catara, Vittoria; Li, Da-Zhi; Long, Gui-You; Li, Na

    2012-09-01

    Xanthomonas axonopodis pv. citri (Xac) is the causal agent of citrus bacterial canker, an economically important disease to world citrus industry. To monitor the infection process of Xac in different citrus plants, the enhanced green florescent protein (EGFP) visualizing system was constructed to visualize the propagation and localization in planta. First, the wild-type Xac was isolated from the diseased leaves of susceptible 'Bingtang' sweet orange, and then the isolated Xac was labeled with EGFP by triparental mating. After PCR identification, the growth kinetics and pathogenicity of the transformants were analyzed in comparison with the wild-type Xac. The EGFP-labeled bacteria were inoculated by spraying on the surface and infiltration in the mesophyll of 'Bingtang' sweet orange leaves. The bacterial cell multiplication and diffusion processes were observed directly under confocal laser scanning microscope at different intervals after inoculation. The results indicated that the EGFP-labeled Xac releasing clear green fluorescence light under fluorescent microscope showed the infection process and had the same pathogenicity as the wild type to citrus. Consequently, the labeled Xac demonstrated the ability as an efficient tool to monitor the pathogen infection.

  6. Expression, purification, crystallization and preliminary X-ray analysis of YaeQ (XAC2396) from Xanthomonas axonopodis pv. citri

    SciTech Connect

    Guzzo, Cristiane R.; Nagem, Ronaldo A. P.; Galvão-Botton, Leonor M. P.; Guimarães, Beatriz G.; Medrano, Francisco J.; Barbosa, João A. R. G.; Farah, Chuck S.

    2005-05-01

    The first crystallographic study of a member of the YaeQ family of proteins, which are conserved in a small group of Gram-negative bacteria, most of which are animal or plant pathogens, is reported. Diffraction data were collected to 1.9 Å resolution and an interpretable electron-density map was obtained. Xanthomonas axonopodis pv. citri YaeQ (XAC2396) is a member of a family of bacterial proteins conserved in several Gram-negative pathogens. Here, the cloning, expression, purification and crystallization of the 182-residue (20.6 kDa) YaeQ protein are described. Recombinant YaeQ containing selenomethionine was crystallized in space group P2{sub 1} and crystals diffracted to 1.9 Å resolution at a synchrotron source. The unit-cell parameters are a = 39.75, b = 91.88, c = 48.03 Å, β = 108.37°. The calculated Matthews coefficient suggests the presence of two YaeQ molecules in the asymmetric unit. Initial experimental phases were calculated by the multiple-wavelength anomalous dispersion technique and an interpretable electron-density map was obtained.

  7. The usage of codons which are similar to stop codons in the genomes of Xylella fastidiosa and Xanthomonas citri.

    PubMed

    Galves-dos-Santos, Dilermando P; Martins-de-Souza, Daniel

    2011-03-01

    During the evolution of living organisms, a natural selection event occurs toward the optimization of their genomes regarding the usage of codons. During this process which is known as codon bias, a set of preferred codons is naturally defined in the genome of a given organism, since there are 61 possible codons (plus 3 stop codons) to 20 amino acids. Such event leads to optimization of metabolic cellular processes such as translational efficiency, RNA stability and energy saving. Although we know why, we do not know how exactly a set of preferred codons for each amino acid is defined for a given genome considering that the usage frequency of each synonymous codons is peculiar to each organism. In order to help answering this question, we analyzed the usage frequency of codons which are similar to stop codons, since a minor mutation on these codons may lead to a stop codon into the open reading frame compromising the protein expression as a result. We found a reduced use of those codons in Xanthomomas axonopodis pv. citri which presents an optimized genome regarding codon usage. On the other hand, such codons are more often used in Xylella fastidiosa, which does not seem to have established codon preferences as previously shown. Our results support that a set of preferred codons is not randomly selected and propose new ideas to the field warranting further experiments in this regard.

  8. Effect of Cyantraniliprole, a Novel Insecticide, on the Inoculation of Candidatus Liberibacter Asiaticus Associated with Citrus Huanglongbing by the Asian Citrus Psyllid (Hemiptera: Liviidae).

    PubMed

    Ammar, El-Desouky; Hall, David G; Alvarez, Juan M

    2015-04-01

    The Asian citrus psyllid (Diaphorina citri Kuwayama) is the principal vector of 'Candidatus Liberibacter asiaticus' (CLas) associated with huanglongbing (HLB), the most serious citrus disease worldwide. New control measures including pesticides are urgently needed to combat HLB, especially to protect young or newly planted citrus trees from CLas-inoculation by vector psyllids. Here, we tested CLas-inoculation by D. citri adults (CLas-exposed, reared on infected plants) by feeding them for 7 d on excised healthy citrus leaves with dry residues of cyantraniliprole (Exirel), a novel insecticide, in comparison with fenpropathrin (Danitol 2.4EC), an insecticide commonly used against D. citri. Fewer adults settled (putatively feeding or probing) on leaves treated with cyantraniliprole than those treated with fenpropathrin or water controls. Also, psyllid adults died at a slower rate on leaves treated with cyantraniliprole than those treated with fenpropathrin, although the final cumulative mortality did not differ between the two treatments. In quantitative real-time polymerase chain reaction tests, 59.0-65.3% of the CLas-exposed psyllid adults were proven to be CLas-positive. Inoculation rates of CLas (using 10 adults per leaf) into untreated healthy citrus leaves (47.5-85%) were significantly higher than rates into leaves treated with cyantraniliprole or fenpropathrin (2.5-12.5%). Reduced inoculation rates to leaves treated with cyantraniliprole probably occurred as a result of reduced feeding or probing by D. citri. The excised leaf assay method, which took only a few weeks compared with up to a year or longer using whole plants, can be an effective tool for testing the effect of new pesticides or other treatments in reducing CLas inoculation or transmission by psyllid vectors.

  9. Crystallization, data collection and data processing of maltose-binding protein (MalE) from the phytopathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Souza, C S; Ferreira, L C S; Thomas, L; Barbosa, J A R G; Balan, A

    2009-02-01

    Maltose-binding protein is the periplasmic component of the ABC transporter responsible for the uptake of maltose/maltodextrins. The Xanthomonas axonopodis pv. citri maltose-binding protein MalE has been crystallized at 293 K using the hanging-drop vapour-diffusion method. The crystal belonged to the primitive hexagonal space group P6(1)22, with unit-cell parameters a = 123.59, b = 123.59, c = 304.20 A, and contained two molecules in the asymetric unit. It diffracted to 2.24 A resolution.

  10. [Rapid Identification of Epicarpium Citri Grandis via Infrared Spectroscopy and Fluorescence Spectrum Imaging Technology Combined with Neural Network].

    PubMed

    Pan, Sha-sha; Huang, Fu-rong; Xiao, Chi; Xian, Rui-yi; Ma, Zhi-guo

    2015-10-01

    To explore rapid reliable methods for detection of Epicarpium citri grandis (ECG), the experiment using Fourier Transform Attenuated Total Reflection Infrared Spectroscopy (FTIR/ATR) and Fluorescence Spectrum Imaging Technology combined with Multilayer Perceptron (MLP) Neural Network pattern recognition, for the identification of ECG, and the two methods are compared. Infrared spectra and fluorescence spectral images of 118 samples, 81 ECG and 37 other kinds of ECG, are collected. According to the differences in tspectrum, the spectra data in the 550-1 800 cm(-1) wavenumber range and 400-720 nm wavelength are regarded as the study objects of discriminant analysis. Then principal component analysis (PCA) is applied to reduce the dimension of spectroscopic data of ECG and MLP Neural Network is used in combination to classify them. During the experiment were compared the effects of different methods of data preprocessing on the model: multiplicative scatter correction (MSC), standard normal variable correction (SNV), first-order derivative(FD), second-order derivative(SD) and Savitzky-Golay (SG). The results showed that: after the infrared spectra data via the Savitzky-Golay (SG) pretreatment through the MLP Neural Network with the hidden layer function as sigmoid, we can get the best discrimination of ECG, the correct percent of training set and testing set are both 100%. Using fluorescence spectral imaging technology, corrected by the multiple scattering (MSC) results in the pretreatment is the most ideal. After data preprocessing, the three layers of the MLP Neural Network of the hidden layer function as sigmoid function can get 100% correct percent of training set and 96.7% correct percent of testing set. It was shown that the FTIR/ATR and fluorescent spectral imaging technology combined with MLP Neural Network can be used for the identification study of ECG and has the advantages of rapid, reliable effect.

  11. The copper resistance operon copAB from Xanthomonas axonopodis pathovar citri: gene inactivation results in copper sensitivity.

    PubMed

    Teixeira, Elaine Cristina; Franco de Oliveira, Julio Cezar; Marques Novo, Maria Teresa; Bertolini, Maria Célia

    2008-02-01

    Xanthomonas axonopodis pv. citri (Xac) causes citrus canker and the completion of the Xac genome sequence has opened up the possibility of investigating basic cellular mechanisms at the genomic level. Copper compounds have been extensively used in agriculture to control plant diseases. The copA and copB genes, identified by annotation of the Xac genome, encode homologues of proteins involved in copper resistance. A gene expression assay by Northern blotting revealed that copA and copB are expressed as a unique transcript specifically induced by copper. Synthesis of the gene products was also induced by copper, reaching a maximum level at 4 h after addition of copper to the culture medium. CopA was a cytosolic protein and CopB was detected in the cytoplasmic membrane. The gene encoding CopA was disrupted by the insertion of a transposon, leading to mutant strains that were unable to grow in culture medium containing copper, even at the lowest CuSO(4) concentration tested (0.25 mM), whereas the wild-type strain was able to grow in the presence of 1 mM copper. Cell suspensions of the wild-type and mutant strains in different copper concentrations were inoculated in lemon leaves to analyse their ability to induce citrus canker symptoms. Cells of mutant strains showed higher sensitivity than the wild-type strain in the presence of copper, i.e. they were not able to induce citrus canker symptoms at high copper concentrations and exhibited a more retarded growth in planta.

  12. Genome-wide mutagenesis of Xanthomonas axonopodis pv. citri reveals novel genetic determinants and regulation mechanisms of biofilm formation.

    PubMed

    Li, Jinyun; Wang, Nian

    2011-01-01

    Xanthomonas axonopodis pv. citri (Xac) causes citrus canker disease, a major threat to citrus production worldwide. Accumulating evidence suggests that the formation of biofilms on citrus leaves plays an important role in the epiphytic survival of this pathogen prior to the development of canker disease. However, the process of Xac biofilm formation is poorly understood. Here, we report a genome-scale study of Xac biofilm formation in which we identified 92 genes, including 33 novel genes involved in biofilm formation and 7 previously characterized genes, colR, fhaB, fliC, galU, gumD, wxacO, and rbfC, known to be important for Xac biofilm formation. In addition, 52 other genes with defined or putative functions in biofilm formation were identified, even though they had not previously reported been to be associated with biofilm formation. The 92 genes were isolated from 292 biofilm-defective mutants following a screen of a transposon insertion library containing 22,000 Xac strain 306 mutants. Further analyses indicated that 16 of the novel genes are involved in the production of extracellular polysaccharide (EPS) and/or lipopolysaccharide (LPS), 7 genes are involved in signaling and regulatory pathways, and 5 genes have unknown roles in biofilm formation. Furthermore, two novel genes, XAC0482, encoding a haloacid dehalogenase-like phosphatase, and XAC0494 (designated as rbfS), encoding a two-component sensor protein, were confirmed to be biofilm-related genes through complementation assays. Our data demonstrate that the formation of mature biofilm requires EPS, LPS, both flagellum-dependent and flagellum-independent cell motility, secreted proteins and extracellular DNA. Additionally, multiple signaling pathways are involved in Xac biofilm formation. This work is the first report on a genome-wide scale of the genetic processes of biofilm formation in plant pathogenic bacteria. The report provides significant new information about the genetic determinants and

  13. Modifications of Xanthomonas axonopodis pv. citri lipopolysaccharide affect the basal response and the virulence process during citrus canker.

    PubMed

    Petrocelli, Silvana; Tondo, María Laura; Daurelio, Lucas D; Orellano, Elena G

    2012-01-01

    Xanthomonas axonopodis pv. citri (Xac) is the phytopathogen responsible for citrus canker, one of the most devastating citrus diseases in the world. A broad range of pathogens is recognized by plants through so-called pathogen-associated molecular patterns (PAMPs), which are highly conserved fragments of pathogenic molecules. In plant pathogenic bacteria, lipopolisaccharyde (LPS) is considered a virulence factor and it is being recognized as a PAMP. The study of the participation of Xac LPS in citrus canker establishment could help to understand the molecular bases of this disease. In the present work we investigated the role of Xac LPS in bacterial virulence and in basal defense during the interaction with host and non host plants. We analyzed physiological features of Xac mutants in LPS biosynthesis genes (wzt and rfb303) and the effect of these mutations on the interaction with orange and tobacco plants. Xac mutants showed an increased sensitivity to external stresses and differences in bacterial motilities, in vivo and in vitro adhesion and biofilm formation. Changes in the expression levels of the LPS biosynthesis genes were observed in a medium that mimics the plant environment. Xacwzt exhibited reduced virulence in host plants compared to Xac wild-type and Xacrfb303. However, both mutant strains produced a lower increase in the expression levels of host plant defense-related genes respect to the parental strain. In addition, Xac LPS mutants were not able to generate HR during the incompatible interaction with tobacco plants. Our findings indicate that the structural modifications of Xac LPS impinge on other physiological attributes and lead to a reduction in bacterial virulence. On the other hand, Xac LPS has a role in the activation of basal defense in host and non host plants.

  14. Genome-Wide Mutagenesis of Xanthomonas axonopodis pv. citri Reveals Novel Genetic Determinants and Regulation Mechanisms of Biofilm Formation

    PubMed Central

    Li, Jinyun; Wang, Nian

    2011-01-01

    Xanthomonas axonopodis pv. citri (Xac) causes citrus canker disease, a major threat to citrus production worldwide. Accumulating evidence suggests that the formation of biofilms on citrus leaves plays an important role in the epiphytic survival of this pathogen prior to the development of canker disease. However, the process of Xac biofilm formation is poorly understood. Here, we report a genome-scale study of Xac biofilm formation in which we identified 92 genes, including 33 novel genes involved in biofilm formation and 7 previously characterized genes, colR, fhaB, fliC, galU, gumD, wxacO, and rbfC, known to be important for Xac biofilm formation. In addition, 52 other genes with defined or putative functions in biofilm formation were identified, even though they had not previously reported been to be associated with biofilm formation. The 92 genes were isolated from 292 biofilm-defective mutants following a screen of a transposon insertion library containing 22,000 Xac strain 306 mutants. Further analyses indicated that 16 of the novel genes are involved in the production of extracellular polysaccharide (EPS) and/or lipopolysaccharide (LPS), 7 genes are involved in signaling and regulatory pathways, and 5 genes have unknown roles in biofilm formation. Furthermore, two novel genes, XAC0482, encoding a haloacid dehalogenase-like phosphatase, and XAC0494 (designated as rbfS), encoding a two-component sensor protein, were confirmed to be biofilm-related genes through complementation assays. Our data demonstrate that the formation of mature biofilm requires EPS, LPS, both flagellum-dependent and flagellum-independent cell motility, secreted proteins and extracellular DNA. Additionally, multiple signaling pathways are involved in Xac biofilm formation. This work is the first report on a genome-wide scale of the genetic processes of biofilm formation in plant pathogenic bacteria. The report provides significant new information about the genetic determinants and

  15. Expression, crystallization and preliminary crystallographic analysis of SufE (XAC2355) from Xanthomonas axonopodis pv. citri

    SciTech Connect

    Guzzo, Cristiane R.; Silva, Lucicleide R.; Galvão-Botton, Leonor M. P.; Barbosa, João A. R. G.; Farah, Chuck S.

    2006-03-01

    Cloning, expression, purification, crystallization and data collection are reported for a member of the SufE family of proteins involved in the biosynthesis of Fe–S clusters in prokaryotes. Diffraction data were collected to 1.9 Å resolution and an interpretable electron-density map has been obtained by molecular replacement. Xanthomonas axonopodis pv. citri (Xac) SufE (XAC2355) is a member of a family of bacterial proteins that are conserved in several pathogens and phytopathogens. The Escherichia coli suf operon is involved in iron–sulfur cluster biosynthesis under iron-limitation and stress conditions. It has recently been demonstrated that SufE and SufS form a novel two-component cysteine desulfarase in which SufS catalyses the conversion of l-cysteine to l-alanine, forming a protein-bound persulfide intermediate. The S atom is then transferred to SufE, from which it is subsequently transferred to target molecules or reduced to sulfide in solution. Here, the cloning, expression, crystallization and phase determination of Xac SufE crystals are described. Recombinant SufE was crystallized in space group P2{sub 1}2{sub 1}2{sub 1} and diffracted to 1.9 Å resolution at a synchrotron source. The unit-cell parameters are a = 45.837, b = 58.507, c = 98.951 Å, α = β = γ = 90°. The calculated Matthews coefficient indicated the presence of two molecules in the asymmetric unit. Phasing was performed by molecular-replacement using E. coli SufE as a model (PDB code 1mzg) and an interpretable map was obtained.

  16. Analysis of Transcriptome Differences between Resistant and Susceptible Strains of the Citrus Red Mite Panonychus citri (Acari: Tetranychidae)

    PubMed Central

    Liu, Bin; Jiang, Gaofei; Zhang, Yunfei; Li, Junli; Li, Xiaojiao; Yue, Jiansu; Chen, Fei; Liu, Haoqiang; Li, Hongjun; Zhu, Shiping; Wang, Jinjun; Ran, Chun

    2011-01-01

    Background The citrus red mite is a worldwide citrus pest and a common sensitizing allergen of asthma and rhinitis. It has developed strong resistance to many registered acaricides, However, the molecular mechanisms of resistance remain unknown. we therefore used next generation sequencing technology to investigate the global transcriptomes between resistant strains and susceptible strains. Results We obtained 34,159, 30,466 and 32,217 unigenes by assembling the SS reads, RS reads and SS&RS reads respectively. There are total 17,581 annotated unigenes from SS&RS reads by BLAST searching databases of nr, the Clusters of Orthologous Groups (COGs) and Kyoto Encyclopedia of Genes and Genomes (KEGG) with an E-value ≤ 1e-5, in which 7,075 unigenes were annotated in the COG database, 12, 712 unigenes were found in the KEGG database and 3,812 unigenes were assigned to Gene ontology (GO). Moreover, 2,701 unigenes were judged to be the differentially expressed genes (DEGs) based on the uniquely mapped reads. There are 219 pathways in all annotated unigenes and 198 pathways in DEGs that mapped to the KEGG database. We identified 211 metabolism genes and target genes related to general insecticide resistance such as P450 and Cytochrome b, and further compared their differences between RS and SS. Meanwhile, we identified 105 and 194 genes related to growth and reproduction, respectively, based on the mode of action of Hexythiazox. After further analyses, we found variation in sequences but not in gene expression related to mite growth and reproduction between different strains. Conclusion To our knowledge, this is the first comparative transcriptome study to discover candidate genes involved in phytophagous mite resistance. This study identified differential unigenes related to general pesticide resistance and organism growth and reproduction in P. citri. The assembled, annotated transcriptomes provide a valuable genomic resource for further understanding the molecular basis

  17. Assessment of Prey Preference by the Generalist Predator, Mallada basalis (Walker), When Offered Two Species of Spider Mites, Tetranychus kanzawai Kishida and Panonychus citri (McGregor) on Papaya

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated potential prey preference of the generalist predator Mallada basalis (Walker) when offered two mites, Tetranychus kanzawai Kishida and Panonychus citri (McGregor), both important pests on papaya. Laboratory choice tests revealed that none of the three larval instars of M. basalis sho...

  18. New protein-protein interactions identified for the regulatory and structural components and substrates of the type III Secretion system of the phytopathogen Xanthomonas axonopodis Pathovar citri.

    PubMed

    Alegria, Marcos C; Docena, Cassia; Khater, Leticia; Ramos, Carlos H I; da Silva, Ana C R; Farah, Chuck S

    2004-09-01

    We have initiated a project to identify protein-protein interactions involved in the pathogenicity of the bacterial plant pathogen Xanthomonas axonopodis pv. citri. Using a yeast two-hybrid system based on Gal4 DNA-binding and activation domains, we have focused on identifying interactions involving subunits, regulators, and substrates of the type III secretion system coded by the hrp (for hypersensitive response and pathogenicity), hrc (for hrp conserved), and hpa (for hrp associated) genes. We have identified several previously uncharacterized interactions involving (i) HrpG, a two-component system response regulator responsible for the expression of X. axonopodis pv. citri hrp operons, and XAC0095, a previously uncharacterized protein encountered only in Xanthomonas spp.; (ii) HpaA, a protein secreted by the type III secretion system, HpaB, and the C-terminal domain of HrcV; (iii) HrpB1, HrpD6, and HrpW; and (iv) HrpB2 and HrcU. Homotropic interactions were also identified for the ATPase HrcN. These newly identified protein-protein interactions increase our understanding of the functional integration of phytopathogen-specific type III secretion system components and suggest new hypotheses regarding the molecular mechanisms underlying Xanthomonas pathogenicity.

  19. Identification of the flagellar chaperone FlgN in the phytopathogen Xanthomonas axonopodis pathovar citri by its interaction with hook-associated FlgK.

    PubMed

    Khater, Letícia; Alegria, Marcos C; Borin, Paula F L; Santos, Túlio M; Docena, Cássia; Tasic, Ljubica; Farah, Chuck S; Ramos, Carlos H I

    2007-09-01

    Genome annotation of the plant pathogen Xanthomonas axonopodis pv. citri (Xac), identified flagellar genes in a 15.7 kb gene cluster. However, FlgN, a secretion chaperone for hook-associated proteins FlgK and FlgL, was not identified. We performed extensive screening of the X. axonopodis pv. citri genome with the yeast two-hybrid system to identify a protein with the characteristics of the flagellar chaperone FlgN. We found a candidate (XAC1990) encoded by an operon for components of the flagellum apparatus that interacted with FlgK. In order to further support this finding, Xac FlgK and XAC1990 were cloned, expressed, and purified. The recombinant proteins were characterized by spectroscopic methods and their interaction in vitro confirmed by pull-down assays. We, therefore, conclude that XAC1990 and its homologs in other Xanthomonas species are, in fact, FlgN proteins. These observations extend the sequence diversity covered by this family of proteins.

  20. Identification of new protein-protein interactions involving the products of the chromosome- and plasmid-encoded type IV secretion loci of the phytopathogen Xanthomonas axonopodis pv. citri.

    PubMed

    Alegria, Marcos C; Souza, Diorge P; Andrade, Maxuel O; Docena, Cassia; Khater, Leticia; Ramos, Carlos H I; da Silva, Ana C R; Farah, Chuck S

    2005-04-01

    The recently sequenced genome of the bacterial plant pathogen Xanthomonas axonopodis pv. citri contains two virB gene clusters, one on the chromosome and one on a 64-kb plasmid, each of which codes for a previously uncharacterized type IV secretion system (T4SS). Here we used a yeast two-hybrid assay to identify protein-protein interactions in these two systems. Our results revealed interactions between known T4SS components as well as previously uncharacterized interactions involving hypothetical proteins coded by open reading frames in the two X. axonopodis pv. citri virB loci. Our results indicate that both loci may code for previously unidentified VirB7 proteins, which we show interact with either VirB6 or VirB9 or with a hypothetical protein coded by the same locus. Furthermore, a set of previously uncharacterized Xanthomonas proteins have been found to interact with VirD4, whose gene is adjacent to the chromosomal virB locus. The gene for one member of this family is found within the chromosomal virB locus. All these uncharacterized proteins possess a conserved 120-amino-acid domain in their C termini and may represent a family of cofactors or substrates of the Xanthomonas T4SS.

  1. Mutants of Saccharomyces cerevisiae and Bacillus citri Changed the Protein Content of the Nigerian Oryza sativa variety “Igbimo” during Fermentation

    PubMed Central

    Boboye, Bolatito E; Adeleke, Mutiat A; Olawale, Anthony O

    2012-01-01

    Effect of mutation on protein production by Saccharomyces cerevisiae and Bacillus citri, the best protein producing yeast and bacterium isolated during a previous natural fermentation of a Nigerian rice (“Igbimo”). The two microorganisms were grown to logarithmic phase and mutagenized separately using ethylmethyl sulphonate (EMS). The wild-types and variants were inoculated individually into sterile “Igbimo” rice. Fermentation was allowed to take place at 27°C for 7 days after which protein released into the rice was quantified using the Biuret reagent method. The data obtained showed that the mutants are different from each other. Some mutants did form the protein at lower concentrations, others at the same and higher concentrations than the mother strains. The parental strains of S. cerevisiae and B. citri synthesized 0.89 mg/mL and 0.36 mg/mL protein respectively. Four groups of the mutants are recognized: classes I, II, III and IV which are the Poor, Average, Good and Super Protein Producers with 0-0.20, 0.21-0.50, 0.51-1.0 and 1.0 mg/mL protein respectively The yeast mutants produced higher amounts of protein than those of the bacterium. PMID:23166568

  2. Distinguishing Galactomyces citri-aurantii from G. geotrichum and characterizing population structure of the two postharvest sour rot pathogens of fruit crops in California.

    PubMed

    McKay, A H; Förster, H; Adaskaveg, J E

    2012-05-01

    A growth assay in lemon juice and polymerase chain reaction amplifications using newly designed species-specific primers from endopolygalacturonase and β-tubulin genes rapidly differentiated isolates of the morphologically similar fruit sour rot pathogens Galactomyces citriaurantii and G. geotrichum. Isolates of both species were collected from agricultural soils and decaying fruit at locations within and outside California, including worldwide locations, and were used in population genetic studies based on amplified fragment length polymorphic (AFLP) DNA markers. For all four geographically defined subpopulations (three counties of California and locations outside California) among 97 isolates of G. citri-aurantii and for the two subpopulations (origin within or outside California) among 35 isolates of G. geotrichum, the proportion of polymorphic loci and haplotypic diversity was high. In total, 82 unique haplotypes were identified for G. citri-aurantii for the four subpopulations and, of these, 80 haplotypes were unique among subpopulations. For G. geotrichum, 25 unique haplotypes were identified among the two subpopulations and no haplotype was shared. Indices of genetic differences (F(ST)) between subpopulations within each species were all low (e.g., 0.038 for G. geotrichum and 0.085 to 0.226 for G. citriaurantii), indicating a low level of genetic differentiation. Following clone correction, mating type segregation ratios for G. citri-aurantii did not significantly (P > 0.1) deviate from a 1:1 ratio for all four subpopulations or the entire population. Tests of the index of association (I(A)) and parsimony tree-length permutation tests (PTLPT) supported a random mating structure for clone-corrected data for the Kern, Tulare, and Ventura County subpopulations and the null hypothesis of random mating could not be rejected. Additionally, PTLPT also supported random mating for the "outside of California" population. For G. geotrichum, random mating was only

  3. Xanthan Gum Removal for 1H-NMR Analysis of the Intracellular Metabolome of the Bacteria Xanthomonas axonopodis pv. citri 306.

    PubMed

    Pegos, Vanessa R; Canevarolo, Rafael R; Sampaio, Aline P; Balan, Andrea; Zeri, Ana C M

    2014-04-22

    Xanthomonas is a genus of phytopathogenic bacteria, which produces a slimy, polysaccharide matrix known as xanthan gum, which involves, protects and helps the bacteria during host colonization. Although broadly used as a stabilizer and thickener in the cosmetic and food industries, xanthan gum can be a troubling artifact in molecular investigations due to its rheological properties. In particular, a cross-reaction between reference compounds and the xanthan gum could compromise metabolic quantification by NMR spectroscopy. Aiming at an efficient gum extraction protocol, for a 1H-NMR-based metabolic profiling study of Xanthomonas, we tested four different interventions on the broadly used methanol-chloroform extraction protocol for the intracellular metabolic contents observation. Lower limits for bacterial pellet volumes for extraction were also probed, and a strategy is illustrated with an initial analysis of X. citri's metabolism by 1H-NMR spectroscopy.

  4. A filamentous hemagglutinin-like protein of Xanthomonas axonopodis pv. citri, the phytopathogen responsible for citrus canker, is involved in bacterial virulence.

    PubMed

    Gottig, Natalia; Garavaglia, Betiana S; Garofalo, Cecilia G; Orellano, Elena G; Ottado, Jorgelina

    2009-01-01

    Xanthomonas axonopodis pv. citri, the phytopathogen responsible for citrus canker has a number of protein secretion systems and among them, at least one type V protein secretion system belonging to the two-partner secretion pathway. This system is mainly associated to the translocation of large proteins such as adhesins to the outer membrane of several pathogens. Xanthomonas axonopodis pv. citri possess a filamentous hemagglutinin-like protein in close vicinity to its putative transporter protein, XacFhaB and XacFhaC, respectively. Expression analysis indicated that XacFhaB was induced in planta during plant-pathogen interaction. By mutation analysis of XacFhaB and XacFhaC genes we determined that XacFhaB is involved in virulence both in epiphytic and wound inoculations, displaying more dispersed and fewer canker lesions. Unexpectedly, the XacFhaC mutant in the transporter protein produced an intermediate virulence phenotype resembling wild type infection, suggesting that XacFhaB could be secreted by another partner different from XacFhaC. Moreover, XacFhaB mutants showed a general lack of adhesion and were affected in leaf surface attachment and biofilm formation. In agreement with the in planta phenotype, adhesin lacking cells moved faster in swarming plates. Since no hyperflagellation phenotype was observed in this bacteria, the faster movement may be attributed to the lack of cell-to-cell aggregation. Moreover, XacFhaB mutants secreted more exopolysaccharide that in turn may facilitate its motility. Our results suggest that this hemagglutinin-like protein is required for tissue colonization being mainly involved in surface attachment and biofilm formation, and that plant tissue attachment and cell-to-cell aggregation are dependent on the coordinated action of adhesin molecules and exopolysaccharides.

  5. All five host-range variants of Xanthomonas citri carry one pthA homolog with 17.5 repeats that determines pathogenicity on citrus, but none determine host-range variation.

    PubMed

    Al-Saadi, Abdulwahid; Reddy, Joseph D; Duan, Yong P; Brunings, Asha M; Yuan, Qiaoping; Gabriel, Dean W

    2007-08-01

    Citrus canker disease is caused by five groups of Xanthomonas citri strains that are distinguished primarily by host range: three from Asia (A, A*, and A(w)) and two that form a phylogenetically distinct clade and originated in South America (B and C). Every X. citri strain carries multiple DNA fragments that hybridize with pthA, which is essential for the pathogenicity of wide-host-range X. citri group A strain 3213. DNA fragments that hybridized with pthA were cloned from a representative strain from all five groups. Each strain carried one and only one pthA homolog that functionally complemented a knockout mutation of pthA in 3213. Every complementing homolog was of identical size to pthA and carried 17.5 nearly identical, direct tandem repeats, including three new genes from narrow-host-range groups C (pthC), A(w) (pthAW), and A* (pthA*). Every noncomplementing paralog was of a different size; one of these was sequenced from group A* (pthA*-2) and was found to have an intact promoter and full-length reading frame but with 15.5 repeats. None of the complementing homologs nor any of the noncomplementing paralogs conferred avirulence to 3213 on grapefruit or suppressed avirulence of a group A* strain on grapefruit. A knockout mutation of pthC in a group C strain resulted in loss of pathogenicity on lime, but the strain was unaffected in ability to elicit an HR on grapefruit. This pthC- mutant was fully complemented by pthA, pthB, or pthC. Analysis of the predicted amino-acid sequences of all functional pthA homologs and nonfunctional paralogs indicated that the specific sequence of the 17th repeat may be essential for pathogenicity of X. citri on citrus.

  6. Orchard and nursery dynamics of the effect of interplanting citrus with guava for Huanglongbing, vector, and disease management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an important pest of citrus in the United States of America primarily because it vectors ‘Candidatus Liberibacter asiaticus’, the bacterium putatively responsible for Asiatic huanglongbing (HLB). Asiatic HLB is con...

  7. 7 CFR 301.76-1 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Citrus Greening and Asian Citrus Psyllid § 301.76-1... Animal and Plant Health Inspection Service of the United States Department of Agriculture. Asian citrus psyllid. The insect known as Asian citrus psyllid (Diaphorina citri Kuwayama) in any stage of...

  8. 7 CFR 301.76-1 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Citrus Greening and Asian Citrus Psyllid § 301.76-1... Animal and Plant Health Inspection Service of the United States Department of Agriculture. Asian citrus psyllid. The insect known as Asian citrus psyllid (Diaphorina citri Kuwayama) in any stage of...

  9. 7 CFR 301.76-1 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Citrus Greening and Asian Citrus Psyllid § 301.76-1... Animal and Plant Health Inspection Service of the United States Department of Agriculture. Asian citrus psyllid. The insect known as Asian citrus psyllid (Diaphorina citri Kuwayama) in any stage of...

  10. 7 CFR 301.76-1 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Citrus Greening and Asian Citrus Psyllid § 301.76-1... Animal and Plant Health Inspection Service of the United States Department of Agriculture. Asian citrus psyllid. The insect known as Asian citrus psyllid (Diaphorina citri Kuwayama) in any stage of...

  11. Interference by western flower thrips in rearing Asian citrus psyllid: damage to host plants and facultative predation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is an important pest of citrus primarily because it vectors a bacterium responsible for a serious citrus disease known as huanglongbing (HLB) (also known as citrus greening disease). Researchers seeking solutions to HLB often depend on labor...

  12. Bionomics of Asian citrus psyllid (Hemiptera: Liviidae) associated with orange jasmine hedges in southest central Florida, with special reference to biological control by Tamarixia radiata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is an important pest in Florida because it vectors bacteria responsible for citrus huanglongbing disease. In addition to infesting citrus, orange jasmine (Murraya paniculata) is one of ACP’s favorite host plants and is widely grown as an orn...

  13. Candidatus Liberibacter asiaticus is present in orange jasmine and Asian citrus psyllid reared from jasmine at low titers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Orange jasmine, Murraya paniculata, is a common horticultural plant in Florida, and an alternate host of the Asian citrus psyllid, Diaphorina citri Kuwayama. Orange jasmine has also been reported to harbor the bacteria Candidatus Liberibacter asiaticus, the causal agent of huanglongbing disease. We ...

  14. Whole plant destructive screening for huanglongbing susceptibility with conetainer seedlings exposed to no-choice Asian citrus psyllid inoculation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB) is associated with Candidatus Liberibacter asiaticus (Las) and is vectored by the Asian Citrus Psyllid (ACP, Diaphorina citri). HLB is devastating the Florida citrus industry, with production reduced by 60 percent in the last 12 years, and HLB is considered the greatest threat to...

  15. Two separate introductions of Asian citrus psyllid populations found in the American continents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A phylogeographic analysis inferred from the partial mitochondrial cytochrome oxidase subunit I gene (433 bp) was performed with 22 populations (n=132) of Diaphorina citri collected in the Americas and one in the Pacific. Eight populations (n=46) from four countries in South America, 14 (n=76) from...

  16. Two founding events identified in Asian citrus psyllid populations collected in the Americas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A phylogeographic analysis inferred from the partial mitochondrial cytochrome oxidase subunit I gene (COI) (433-bp) was performed with 22 populations (n=121) of Diaphorina citri collected in the Americas. Eight populations (n=46) from four countries in South America and 14 populations (n=75) from f...

  17. Comparative analysis of Asian citrus psyllid and Potato psyllid antennae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The comparative investigation of the morphological basis for olfactory reception in two psyllid species, Diaphorina citri (the Asian citrus psyllid), and Bacterocera cockerelli (the potato/tomato psyllid) (both species Hemiptera:Psyllidae) was performed using scanning electron microscopy to elucidat...

  18. PROCENTAJE DE PSILIDOS PORTADORES DE Canidatus Liberibacter asiaticus Y SU RELACION CON LA INCIDENCIA DE HLB EN CINCO HUERTAS COMERCIALES DE LIMON MEXICANO {Citrus aurantifolia (Christm) Swingle} EN EL ESTADO DE COLIMA MEXICO

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Asian citrus psyllids (Diaphorina citri) were individually analyzed by qPCR to detect Candidatus Liberibacter asiaticus (CLas). The psyllids were collected in Mexican lime (Citrus aurantifolia) trees in five commercial orchards in Tecomán and Manzanillo, Colima with severe symptoms of classical mott...

  19. Effects of soil-applied imidacloprid on Asian citrus psyllid (Hemiptera: Psyllidae) feeding behavior

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid, Diaphorina citri Kuwayama is one of the most important pests of citrus due to its status as a vector of Candidatus Liberibacter asiaticus, the bacterium associated with huanglongbing (HLB) disease. The use of insecticides for vector control is the primary method of managing...

  20. Visualization of ‘Candidatus Liberibacter asiaticus’ cells in citrus seed coats with fluorescence in situ hybridization and transmission electron microscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ‘Candidatus Liberibacter asiaticus’ is bacterium implicated as the causal agent of the economically damaging disease of citrus called huanglongbing (HLB). The bacterium is spread by movement of infected citrus propagation material and by the Asian citrus psyllid, Diaphorina citri Kuwayama. Seed tr...

  1. Trailers transporting oranges to processing plants move Asian citrus psyllids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (citrus greening) is one of the most serious of citrus diseases. Movement of the disease occurs as a result of natural vector-borne infection and by movement of plant material. We demonstrate here that Diaphorina citri Kuwayama (vector of citrus greening pathogens) can be transported i...

  2. Incidence of Huanglongbing in Psyllids Under Natural Conditions in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB) was first reported in Florida in August 2005. The disease is spread by a psyllid vector, Diaphorina citri, which has been present in Florida since 1998. HLB is a very difficult disease to manage because of lack of early diagnostic methods. PCR diagnostic methods are efficient onl...

  3. Improved real-time PCR detection of Candidatus Liberibacter asiaticus from citrus and psyllid hosts by targeting the intragenic tandem repeats of its prophage genes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Candidatus Liberibacter asiaticus (Las) is the most prevalent species of Liberibacter associated with citrus huanglongbing (HLB) worldwide. Residing in phloem sieve cells of host plants and vectored by the Asian citrus psyllid (Diaphorina citri), this fastidious bacterium lives as a pathogen or sym...

  4. A phagostimulant blend for the Asian citrus psyllid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chemical cues that condition orientation by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), are of great interest because it is the primary vector of the causal pathogen of citrus greening disease. Previous work in our lab identified a blend of formic and acetic acids as s...

  5. Broad sprectrum potential of Isaria fumosorosea on insect pests of citrus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Use of entomopathogenic fungi, Isaria fumosorosea, Ifr, =Paecilomyces fumosoroseus, successfully increased insect pest mortality. Spraying the Ifr containing product, PFR97 TM, on citrus seedlings was used to screen efficacy for the management of Asian citrus psyllid, Diaphorina citri; glassy-winge...

  6. Degradation products of citrus volatile organic compounds (VOCs) acting as phagostimulants that increase probing behavior of Asian citrus psyllid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Volatile phytochemicals play a role in orientation by phytophagous insects. We studied antennal and behavioral responses of the Asian citrus psyllid, Diaphorina citri Kuwayama, vector of the citrus greening disease pathogen. Little or no response to citrus leaf volatiles was detected by electroanten...

  7. Transmission efficiency of Candidatus Liberibacter asiaticus and progression of Huanglongbing disease in graft- and psyllid-inoculated citrus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Candidatus Liberibacter asiaticus (Las) is a phloem-limited bacterium associated with Huanglongbing (HLB), one of the most destructive diseases of citrus in Florida and other citrus-producing countries. Natural transmission of Las occurs by the psyllid vector Diaphorina citri, but transmission can a...

  8. Factors affecting transmission rates of 'Candidatus Liberibacter asiaticus' by Asian citrus psyllid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP), Diaphorina citri, is an important pest because it transmits a bacterium ‘Candidatus Liberibacter asiaticus’ (CLas) responsible for a serious disease of citrus known as Asiatic huanglongbing (citrus greening disease). USDA-ARS researchers recently established a program...

  9. Evaluation of low-volume sprayers used in asian citrus Psyllid control applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (Diaphorina citri Kumayama, Sternorrhyncha: Psyllidae) is a detrimental pest to citrus crops when it serves as a vector of the pathogen that causes greening (huanglongbing, or HLB). Transmission of this disease causes mottling, chlorosis, dieback and reductions in both frui...

  10. Complete Genome sequence of citrus huanglongbing bacterium, ‘Candidatus Liberibacter asiaticus’ obtained through metagenomics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus huanglongbing (HLB) is the most destructive disease of citrus worldwide. It is spread by the citrus psyllids (Diaphorina citri and Trioza erytreae), and is associated with low-titer, phloem-limited infections by any of the three uncultured species of a-Proteobacteria: 'Candidatus Liberibact...

  11. Development of SSR Markers for Detection, Genotyping, and Genetic Diversity Assessment of “Candidatus Liberibacter asiaticus”

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing, previously known as citrus greening, is a destructive disease of citrus. The causative pathogen is believed to be a phloem-restricted bacteria, “Candidatus Liberibacter” which is naturally transmitted by the citrus psyllid, Diaphorina citri in Asia and America, and Trioza erytreae in ...

  12. Evaluating citrus germplasm for huanglongbing (HLB) resistance: USDA-ARS Inoculation Program

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Asian citrus psyllid (ACP), Diaphorina citri, is an important pest because it vectors bacteria responsible for a serious disease of citrus known as huanglongbing (citrus greening disease). USDA-ARS researchers recently established a program for screening citrus germplasm for resistance to the di...

  13. Ultrastructure of the salivary glands, alimentary canal and bacteria-like organisms in the Asian citrus psyllid, vector of citrus huanglongbing-disease bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several psyllids (Hemiptera: Psylloidea) are known as vectors of some economically important viral and bacterial plant pathogens. The Asian citrus psyllid (ACP, Diaphorina citri, Hemiptera, Liviidae) is the principal vector of ‘Candidatus Liberibacter asiaticus’ (Las), the putative bacterial causal ...

  14. Population levels of Asian Citrus Psyllid in Florida, Texas and Puerto Rico as indicated by yellow sticky traps deployed in citrus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was conducted to compare population levels of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae) in Florida, Texas and Puerto Rico. Four grove locations were studied in Florida, one location near each of the following cities: Leesburg, Vero Beach, Fort Pierce, and Immoka...

  15. Viability of ‘Candidatus Liberibacter asiaticus’ prolonged by addition of citrus juice to culture medium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing, or citrus greening disease, is associated with infection by the phloem-limited bacterium ‘Candidatus Liberibacter asiaticus’ (LAS). Infection with LAS, vectored by the Asian citrus psyllid (Diaphorina citri), is incurable; therefore, knowledge regarding LAS biology and pathogenesis is...

  16. Increased infestation of Asian citrus psyllids on cold treated sour orange seedlings: Its possible relation to biochemical changes in leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cold-stressed sour orange seedling (Citrus aurantium L.) attracted significantly more Asian citrus psyllid (ACP) (Diaphorina citri Kuwayama) during 5h and 24h recovery periods compared to control plants in choice test experiment. Cold stressed plants were held/ placed at 6 ± 1°C for 6 days and then ...

  17. Transmission and propagation of ‘Candidatus Liberibacter asiaticus’ by grafting with individual citrus leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (HLB) is a chronic, progressive decline disease in citrus associated with systemic infection by the bacterium Candidatus Liberibacter asiaticus (CLas). Transmission in the field is by the Asian citrus psyllid (ACP), Diaphorina citri, Kuwayama. Experimental propagation of CLas is done c...

  18. Effect of yeast cell product (CitriStim) supplementation on turkey performance and intestinal immune cell parameters during an experimental lipopolysaccharide injection.

    PubMed

    Shanmugasundaram, Revathi; Sifri, Mamduh; Jeyabalan, Ramesh; Selvaraj, Ramesh K

    2014-11-01

    An experiment was conducted to identify the effect of whole yeast cell product supplementation in turkeys following an experimental inflammatory challenge. A total of 105 one-day-old turkey tom poults were fed basal diets supplemented with 0, 0.1, and 0.2% whole yeast cell product (CitriStim, ADM, Quincy, IL). At 6 wk of age and 16 wk of age, turkeys were injected with lipopolysaccharide (LPS) at 0 or 0.25 mg/kg of BW in a 3 × 2 factorial arrangement. BW gain (P = 0.31) and feed conversion ratio (P = 0.53; 3.13, 2.94, and 2.98 for the 0, 0.10, and 0.20% CitriStim treatments, respectively) at 15 wk of age were not significantly affected by the treatment diets. Yeast cell wall product supplementation had no effect on growth in control-injected turkeys but decreased growth in LPS-injected turkeys (yeast × LPS, P < 0.05). Splenic macrophages from birds fed whole yeast cell product and injected with LPS produced higher (P < 0.01) nitric oxide than the control group injected with LPS at both 6 and 16 wk of age. At 6 and 16 wk of age, birds injected with LPS (P < 0.01; P < 0.01) and supplemented with whole yeast cell product (P = 0.05; P = 0.10) showed increased IL-1 mRNA amounts in cecal tonsils. In birds not injected with LPS, whole yeast cell supplementation increased regulatory T cell percentage and IL-10 mRNA amounts, whereas in birds injected with LPS, whole yeast cell supplementation decreased IL-10 mRNA amounts at both 6 (P < 0.01) and 16 wk (P = 0.01) of age in cecal tonsils. Whole yeast cell product supplementation increased Lactobacillus (P < 0.01 and P = 0.01) and Bifidobacteria (P < 0.01 and P = 0.01) population at 6 and 16 wk of age. In conclusion, the effect of feeding whole yeast cell product on turkeys was dependent on the inflammatory status of the bird.

  19. A new member of the ribbon-helix-helix transcription factor superfamily from the plant pathogen Xanthomonas axonopodis pv.citri.

    PubMed

    Gallo, Mariana; Ferrari, Elena; Eliseo, Tommaso; Amata, Irene; Pertinhez, Thelma A; Katsuyama, Angela M; Paci, Maurizio; Farah, Chuck S; Spisni, Alberto; Cicero, Daniel O

    2010-04-01

    XACb0070 is an uncharacterized protein coded by the two large plasmids isolated from Xanthomonas axonopodis pv. citri, the agent of citrus canker and responsible for important economical losses in citrus world production. XACb0070 presents sequence homology only with other hypothetical proteins belonging to plant pathogens, none of which have their structure determined. The NMR-derived solution structure reveals this protein is a homodimer in which each monomer presents two domains with different structural and dynamic properties: a folded N-terminal domain with beta alpha alpha topology which mediates dimerization and a long disordered C-terminal tail. The folded domain shows high structural similarity to the ribbon-helix-helix transcriptional repressors, a family of DNA-binding proteins of conserved 3D fold but low sequence homology: indeed XACb0070 binds DNA. Primary sequence and fold comparison of XACb0070 with other proteins of the ribbon-helix-helix family together with examination of the genes in the vicinity of xacb0070 suggest the protein might be the component of a toxin-antitoxin system.

  20. The filamentous phage XacF1 causes loss of virulence in Xanthomonas axonopodis pv. citri, the causative agent of citrus canker disease.

    PubMed

    Ahmad, Abdelmonim Ali; Askora, Ahmed; Kawasaki, Takeru; Fujie, Makoto; Yamada, Takashi

    2014-01-01

    In this study, filamentous phage XacF1, which can infect Xanthomonas axonopodis pv. citri (Xac) strains, was isolated and characterized. Electron microscopy showed that XacF1 is a member of the family Inoviridae and is about 600 nm long. The genome of XacF1 is 7325 nucleotides in size, containing 13 predicted open reading frames (ORFs), some of which showed significant homology to Ff-like phage proteins such as ORF1 (pII), ORF2 (pV), ORF6 (pIII), and ORF8 (pVI). XacF1 showed a relatively wide host range, infecting seven out of 11 strains tested in this study. Frequently, XacF1 was found to be integrated into the genome of Xac strains. This integration occurred at the host dif site (attB) and was mediated by the host XerC/D recombination system. The attP sequence was identical to that of Xanthomonas phage Cf1c. Interestingly, infection by XacF1 phage caused several physiological changes to the bacterial host cells, including lower levels of extracellular polysaccharide production, reduced motility, slower growth rate, and a dramatic reduction in virulence. In particular, the reduction in virulence suggested possible utilization of XacF1 as a biological control agent against citrus canker disease.

  1. Organization and nucleotide sequences of the Spiroplasma citri genes for ribosomal protein S2, elongation factor Ts, spiralin, phosphofructokinase, pyruvate kinase, and an unidentified protein.

    PubMed Central

    Chevalier, C; Saillard, C; Bové, J M

    1990-01-01

    The gene for spiralin, the major membrane protein of the helical mollicute Spiroplasma citri, was cloned in Escherichia coli as a 5-kilobase-pair (kbp) DNA fragment. The complete nucleotide sequence of the 5.0-kbp spiroplasmal DNA fragment was determined (GenBank accession no. M31161). The spiralin gene was identified by the size and amino acid composition of its translational product. Besides the spiralin gene, the spiroplasmal DNA fragment was found to contain five additional open reading frames (ORFs). The translational products of four of these ORFs were identified by their amino acid sequence homologies with known proteins: ribosomal protein S2, elongation factor Ts, phosphofructokinase, and pyruvate kinase, respectively encoded by the genes rpsB, tsf, pfk, and pyk. The product of the fifth ORF remains to be identified and was named protein X (X gene). The order of the above genes was tsf--X--spiralin gene--pfk--pyk. These genes were transcribed in one direction, while the gene for ribosomal protein S2 (rpsB) was transcribed in the opposite direction. Images PMID:2139649

  2. Evaluation of suitable reference genes for quantitative RT-PCR during development and abiotic stress in Panonychus citri (McGregor) (Acari: Tetranychidae).

    PubMed

    Niu, Jin-Zhi; Dou, Wei; Ding, Tian-Bo; Yang, Li-Hong; Shen, Guang-Mao; Wang, Jin-Jun

    2012-05-01

    Quantitative real time reverse transcriptase polymerase chain reaction (RT-qPCR) is preferred for gene expression analysis in living organisms. Currently, it is a valuable tool for biological and ecological studies as it provides a relatively straightforward way to assess the relevance of transcriptional regulation under developmental and stress tolerance conditions. However, studies have shown that some commonly used reference genes varied among different experimental treatments, thus, systematic evaluation of reference genes is critical for gene expression profiling, which is often neglected in gene expression studies of arthropods. The aim of this study is to identify the suitable reference genes for RT-qPCR experiments involving various developmental stages and/or under abiotic stresses in citrus red mite Panonychus citri, a key pest in citrus orchards worldwide. GeNorm, NormFinder, and Bestkeeper software analysis indicates that elongation factor-1 alpha (ELF1A), RNA polymerase II largest subunit, alpha tublin, and glyceraldhyde-3-phosphate dehydrogenase (GAPDH) are the most stable reference genes in various developmental stages, meanwhile, ELF1A and GAPDH were the most stable reference genes under various abiotic stresses. Furthermore, this study will serve as a resource to screen reference genes for gene expression studies in any other spider mite species.

  3. Polymyositis - adult

    MedlinePlus

    ... rash is a sign of a similar condition, dermatomyositis . Common symptoms include: Muscle weakness in the shoulders ... in the treatment of refractory adult and juvenile dermatomyositis and adult polymyositis: a randomized, placebo-phase trial. ...

  4. Wolbachia infection density in populations of the Asian citrus psyllid (Hemiptera: Liviidae).

    PubMed

    Hoffmann, M; Coy, M R; Kingdom Gibbard, H N; Pelz-Stelinski, K S

    2014-10-01

    The symbiotic relationships between bacteria of the genus Wolbachia (order Rickettsiales) and their arthropod hosts are diverse and can range from mutualism to parasitism. Whereas effects of Wolbachia on host biology are well investigated, little is known about diversity and abundance of Wolbachia in their natural hosts. The phloem-feeding Asian citrus psyllid, Diaphorina citri (Kuwayama) (Hemiptera: Liviidae), is naturally infected with Wolbachia (wDi). In the current study, we calculated the within-host density of Wolbachia in Florida D. citri populations using quantitative polymerase chain reaction for detection of the Wolbachia outer surface protein gene, wsp. Gene quantities were normalized to the D. citri wingless gene (Wg) to estimate Wolbachia abundance in individual D. citri. Using this method, significant geographic differences in Wolbachia densities were detected among Florida D. citri populations, with higher infection levels occurring in male versus female hosts.

  5. Super CitriMax (HCA-SX) attenuates increases in oxidative stress, inflammation, insulin resistance, and body weight in developing obese Zucker rats.

    PubMed

    Asghar, Mohammad; Monjok, Emmanuel; Kouamou, Ghislaine; Ohia, Sunny E; Bagchi, Debasis; Lokhandwala, Mustafa F

    2007-10-01

    Super CitriMax (HCA-SX) is a novel calcium/potassium salt of (-)-hydroxycitric acid extracted from the dried fruit rind of the plant Garcinia cambogia, and commonly consumed as weight loss dietary supplement. In the present study, we investigated the effect of HCA-SX on inflammation, oxidative stress and insulin resistance in developing obese Zucker rats, an animal model of type II diabetes associated with inflammation and oxidative stress. Male Zucker rats (5-week old) were supplemented with vehicle (control) and HCA-SX in drinking water for 7 weeks. Oxidative stress markers, including malondialdehyde (MDA), protein carbonyl (DNPH), and protein tyrosine nitration (tyr-NO(2)) were measured in the liver and kidney tissues using biochemical and immunoblotting techniques. Compared to controls, the levels of MDA, DNPH and tyr-NO(2) were lower in the liver and kidney of HCA-SX-treated animals. Furthermore, the levels of C-reactive protein and interleukin-6, markers of inflammation measured by ELISA, were lower in the plasma of HCA-SX-supplemented animals compared to controls, as were levels of fasting plasma insulin, glucose, and triglycerides. Interestingly, insulin resistance did not develop in HCA-SX-supplemented rats. Food-intake and body weight gain was also lower in rats supplemented with HCA-SX compared to their control counterparts. These results suggest that HCA-SX supplementation in obese Zucker rats reduces food-intake, body weight gain, and also attenuates the increases in inflammation, oxidative stress, and insulin resistance observed in untreated animals. Therefore, HCA-SX may be used as an intervention to overcome obesity-related complications, including inflammation, oxidative stress, and insulin resistance.

  6. Transcriptional analysis of the sweet orange interaction with the citrus canker pathogens Xanthomonas axonopodis pv. citri and Xanthomonas axonopodis pv. aurantifolii.

    PubMed

    Cernadas, Raúl Andrés; Camillo, Luciana Rodrigues; Benedetti, Celso Eduardo

    2008-09-01

    Xanthomonas axonopodis pv. citri (Xac) and Xanthomonas axonopodis pv. aurantifolii pathotype C (Xaa) are responsible for citrus canker disease; however, while Xac causes canker on all citrus varieties, Xaa is restricted to Mexican lime, and in sweet oranges it triggers a defence response. To gain insights into the differential pathogenicity exhibited by Xac and Xaa and to survey the early molecular events leading to canker development, a detailed transcriptional analysis of sweet orange plants infected with the pathogens was performed. Using differential display, suppressed subtractive hybridization and microarrays, we identified changes in transcript levels in approximately 2.0% of the approximately 32,000 citrus genes examined. Genes with altered expression in response to Xac/Xaa surveyed at 6 and 48 h post-infection (hpi) were associated with cell-wall modifications, cell division and expansion, vesicle trafficking, disease resistance, carbon and nitrogen metabolism, and responses to hormones auxin, gibberellin and ethylene. Most of the genes that were commonly modulated by Xac and Xaa were associated with basal defences triggered by pathogen-associated molecular patterns, including those involved in reactive oxygen species production and lignification. Significantly, we detected clear changes in the transcriptional profiles of defence, cell-wall, vesicle trafficking and cell growth-related genes in Xac-infected leaves between 6 and 48 hpi. This is consistent with the notion that Xac suppresses host defences early during infection and simultaneously changes the physiological status of the host cells, reprogramming them for division and growth. Notably, brefeldin A, an inhibitor of vesicle trafficking, retarded canker development. In contrast, Xaa triggered a mitogen-activated protein kinase signalling pathway involving WRKY and ethylene-responsive transcriptional factors known to activate downstream defence genes.

  7. A plant natriuretic peptide-like molecule of the pathogen Xanthomonas axonopodis pv. citri causes rapid changes in the proteome of its citrus host

    PubMed Central

    2010-01-01

    Background Plant natriuretic peptides (PNPs) belong to a novel class of peptidic signaling molecules that share some structural similarity to the N-terminal domain of expansins and affect physiological processes such as water and ion homeostasis at nano-molar concentrations. The citrus pathogen Xanthomonas axonopodis pv. citri possesses a PNP-like peptide (XacPNP) uniquely present in this bacteria. Previously we observed that the expression of XacPNP is induced upon infection and that lesions produced in leaves infected with a XacPNP deletion mutant were more necrotic and lead to earlier bacterial cell death, suggesting that the plant-like bacterial PNP enables the plant pathogen to modify host responses in order to create conditions favorable to its own survival. Results Here we measured chlorophyll fluorescence parameters and water potential of citrus leaves infiltrated with recombinant purified XacPNP and demonstrate that the peptide improves the physiological conditions of the tissue. Importantly, the proteomic analysis revealed that these responses are mirrored by rapid changes in the host proteome that include the up-regulation of Rubisco activase, ATP synthase CF1 α subunit, maturase K, and α- and β-tubulin. Conclusions We demonstrate that XacPNP induces changes in host photosynthesis at the level of protein expression and in photosynthetic efficiency in particular. Our findings suggest that the biotrophic pathogen can use the plant-like hormone to modulate the host cellular environment and in particular host metabolism and that such modulations weaken host defence. PMID:20302677

  8. A TALE of Transposition: Tn3-Like Transposons Play a Major Role in the Spread of Pathogenicity Determinants of Xanthomonas citri and Other Xanthomonads

    PubMed Central

    Ferreira, Rafael Marini; de Oliveira, Amanda Carolina P.; Moreira, Leandro M.; Belasque, José; Gourbeyre, Edith; Siguier, Patricia; Ferro, Maria Inês T.; Ferro, Jesus A.

    2015-01-01

    ABSTRACT Members of the genus Xanthomonas are among the most important phytopathogens. A key feature of Xanthomonas pathogenesis is the translocation of type III secretion system (T3SS) effector proteins (T3SEs) into the plant target cells via a T3SS. Several T3SEs and a murein lytic transglycosylase gene (mlt, required for citrus canker symptoms) are found associated with three transposition-related genes in Xanthomonas citri plasmid pXAC64. These are flanked by short inverted repeats (IRs). The region was identified as a transposon, TnXax1, with typical Tn3 family features, including a transposase and two recombination genes. Two 14-bp palindromic sequences within a 193-bp potential resolution site occur between the recombination genes. Additional derivatives carrying different T3SEs and other passenger genes occur in different Xanthomonas species. The T3SEs include transcription activator-like effectors (TALEs). Certain TALEs are flanked by the same IRs as found in TnXax1 to form mobile insertion cassettes (MICs), suggesting that they may be transmitted horizontally. A significant number of MICs carrying other passenger genes (including a number of TALE genes) were also identified, flanked by the same TnXax1 IRs and delimited by 5-bp target site duplications. We conclude that a large fraction of T3SEs, including individual TALEs and potential pathogenicity determinants, have spread by transposition and that TnXax1, which exhibits all of the essential characteristics of a functional transposon, may be involved in driving MIC transposition. We also propose that TALE genes may diversify by fork slippage during the replicative Tn3 family transposition. These mechanisms may play a crucial role in the emergence of Xanthomonas pathogenicity. PMID:25691597

  9. Crystallization and preliminary X-ray diffraction analysis of XAC1151, a small heat-shock protein from Xanthomonas axonopodis pv. citri belonging to the α-crystallin family

    SciTech Connect

    Hilario, Eduardo; Teixeira, Elaine Cristina; Pedroso, Gisele Audrei; Bertolini, Maria Célia; Medrano, Francisco Javier

    2006-05-01

    XAC1151, a small heat-shock protein from X. axonopodis pv. citri belonging to the α-crystallin family, was crystallized using the sitting-drop vapour-diffusion method in the presence of ammonium phosphate. X-ray diffraction data were collected to 1.65 Å resolution using a synchrotron-radiation source. The hspA gene (XAC1151) from Xanthomonas axonopodis pv. citri encodes a protein of 158 amino acids that belongs to the small heat-shock protein (sHSP) family of proteins. These proteins function as molecular chaperones by preventing protein aggregation. The protein was crystallized using the sitting-drop vapour-diffusion method in the presence of ammonium phosphate. X-ray diffraction data were collected to 1.65 Å resolution using a synchrotron-radiation source. The crystal belongs to the rhombohedral space group R3, with unit-cell parameters a = b = 128.7, c = 55.3 Å. The crystal structure was solved by molecular-replacement methods. Structure refinement is in progress.

  10. CPR: Adult

    MedlinePlus

    Refresher Center Home FIRST AID, CPR and AED LIFEGUARDING Refresher Putting It All Together: CPR—Adult (2:03) Refresher videos only utilize this player QUICK LINKS Home RedCross.org Purchase Course ...

  11. Annotation of the Asian Citrus Psyllid Genome Reveals a Reduced Innate Immune System

    PubMed Central

    Arp, Alex P.; Hunter, Wayne B.; Pelz-Stelinski, Kirsten S.

    2016-01-01

    Citrus production worldwide is currently facing significant losses due to citrus greening disease, also known as Huanglongbing. The citrus greening bacteria, Candidatus Liberibacter asiaticus (CLas), is a persistent propagative pathogen transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). Hemipterans characterized to date lack a number of insect immune genes, including those associated with the Imd pathway targeting Gram-negative bacteria. The D. citri draft genome was used to characterize the immune defense genes present in D. citri. Predicted mRNAs identified by screening the published D. citri annotated draft genome were manually searched using a custom database of immune genes from previously annotated insect genomes. Toll and JAK/STAT pathways, general defense genes Dual oxidase, Nitric oxide synthase, prophenoloxidase, and cellular immune defense genes were present in D. citri. In contrast, D. citri lacked genes for the Imd pathway, most antimicrobial peptides, 1,3-β-glucan recognition proteins (GNBPs), and complete peptidoglycan recognition proteins. These data suggest that D. citri has a reduced immune capability similar to that observed in A. pisum, P. humanus, and R. prolixus. The absence of immune system genes from the D. citri genome may facilitate CLas infections, and is possibly compensated for by their relationship with their microbial endosymbionts. PMID:27965582

  12. Annotation of the Asian Citrus Psyllid Genome Reveals a Reduced Innate Immune System.

    PubMed

    Arp, Alex P; Hunter, Wayne B; Pelz-Stelinski, Kirsten S

    2016-01-01

    Citrus production worldwide is currently facing significant losses due to citrus greening disease, also known as Huanglongbing. The citrus greening bacteria, Candidatus Liberibacter asiaticus (CLas), is a persistent propagative pathogen transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). Hemipterans characterized to date lack a number of insect immune genes, including those associated with the Imd pathway targeting Gram-negative bacteria. The D. citri draft genome was used to characterize the immune defense genes present in D. citri. Predicted mRNAs identified by screening the published D. citri annotated draft genome were manually searched using a custom database of immune genes from previously annotated insect genomes. Toll and JAK/STAT pathways, general defense genes Dual oxidase, Nitric oxide synthase, prophenoloxidase, and cellular immune defense genes were present in D. citri. In contrast, D. citri lacked genes for the Imd pathway, most antimicrobial peptides, 1,3-β-glucan recognition proteins (GNBPs), and complete peptidoglycan recognition proteins. These data suggest that D. citri has a reduced immune capability similar to that observed in A. pisum, P. humanus, and R. prolixus. The absence of immune system genes from the D. citri genome may facilitate CLas infections, and is possibly compensated for by their relationship with their microbial endosymbionts.

  13. Crystallization and preliminary X-ray diffraction analysis of XAC1151, a small heat-shock protein from Xanthomonas axonopodis pv. citri belonging to the alpha-crystallin family.

    PubMed

    Hilario, Eduardo; Teixeira, Elaine Cristina; Pedroso, Gisele Audrei; Bertolini, Maria Célia; Medrano, Francisco Javier

    2006-05-01

    The hspA gene (XAC1151) from Xanthomonas axonopodis pv. citri encodes a protein of 158 amino acids that belongs to the small heat-shock protein (sHSP) family of proteins. These proteins function as molecular chaperones by preventing protein aggregation. The protein was crystallized using the sitting-drop vapour-diffusion method in the presence of ammonium phosphate. X-ray diffraction data were collected to 1.65 angstroms resolution using a synchrotron-radiation source. The crystal belongs to the rhombohedral space group R3, with unit-cell parameters a = b = 128.7, c = 55.3 angstroms. The crystal structure was solved by molecular-replacement methods. Structure refinement is in progress.

  14. Lethal and Sublethal Effects of Insecticides Used on Citrus, on the Ectoparasitoid Tamarixia radiata

    PubMed Central

    Beloti, Vitor Hugo; Alves, Gustavo Rodrigues; Araújo, Diogo Feliciano Dias; Picoli, Mateus Manara; Moral, Rafael de Andrade; Demétrio, Clarice Garcia Borges; Yamamoto, Pedro Takao

    2015-01-01

    Huanglongbing (HLB) is a disease associated with the bacteria “Candidatus Liberibacter spp.” and has been devastating citrus orchards around the world. Its management involves control of the insect vector, the Asian citrus psyllid Diaphorina citri Kuwayama. However, the indiscriminate use of chemicals has caused pest outbreaks and eliminated the natural enemies of the vector, such as the parasitoid Tamarixia radiata (Waterston), the main agent for biological control of D. citri. This study assessed the lethal and sublethal effects of insecticides recommended for integrated production of citrus on the parasitoid T. radiata. When adult parasitoids were exposed to residues of 25 insecticides, 20% of them, i.e., gamma-cyhalothrin, etofenprox, azadirachtin, tebufenozide and pyriproxyfen, were considered as harmless (Class 1), 12% as slightly harmful (Class 2), 12% as moderately harmful (Class 3) and 56% as harmful (Class 4), according to the classification proposed by the IOBC/WPRS. Afterward, 14 insecticides (5 harmless and 9 harmful) were sprayed on the parasitoid pupae. Of the 14 insecticides tested, only the organophosphates dimethoate and chlorpyrifos affected the parasitoid emergence. The effects of insecticides on the parasitism capacity of adults exposed to residues of azadirachtin, etofenprox, gamma-cyhalothrin, pyriproxyfen and tebufenozide (harmless) were also evaluated. Tebufenozide and gamma-cyhalothrin affected the parasitism of the F0 generation, but did not affect the emergence of the F1 and F2 generations. Therefore, for an effective IPM program, selective insecticides or harmful pesticides to adult parasitoids could be used in the field, provided that the adults do not occur naturally and the chemical applications do not coincide with parasitoid releases. PMID:26132327

  15. Lethal and Sublethal Effects of Insecticides Used on Citrus, on the Ectoparasitoid Tamarixia radiata.

    PubMed

    Beloti, Vitor Hugo; Alves, Gustavo Rodrigues; Araújo, Diogo Feliciano Dias; Picoli, Mateus Manara; Moral, Rafael de Andrade; Demétrio, Clarice Garcia Borges; Yamamoto, Pedro Takao

    2015-01-01

    Huanglongbing (HLB) is a disease associated with the bacteria "Candidatus Liberibacter spp." and has been devastating citrus orchards around the world. Its management involves control of the insect vector, the Asian citrus psyllid Diaphorina citri Kuwayama. However, the indiscriminate use of chemicals has caused pest outbreaks and eliminated the natural enemies of the vector, such as the parasitoid Tamarixia radiata (Waterston), the main agent for biological control of D. citri. This study assessed the lethal and sublethal effects of insecticides recommended for integrated production of citrus on the parasitoid T. radiata. When adult parasitoids were exposed to residues of 25 insecticides, 20% of them, i.e., gamma-cyhalothrin, etofenprox, azadirachtin, tebufenozide and pyriproxyfen, were considered as harmless (Class 1), 12% as slightly harmful (Class 2), 12% as moderately harmful (Class 3) and 56% as harmful (Class 4), according to the classification proposed by the IOBC/WPRS. Afterward, 14 insecticides (5 harmless and 9 harmful) were sprayed on the parasitoid pupae. Of the 14 insecticides tested, only the organophosphates dimethoate and chlorpyrifos affected the parasitoid emergence. The effects of insecticides on the parasitism capacity of adults exposed to residues of azadirachtin, etofenprox, gamma-cyhalothrin, pyriproxyfen and tebufenozide (harmless) were also evaluated. Tebufenozide and gamma-cyhalothrin affected the parasitism of the F0 generation, but did not affect the emergence of the F1 and F2 generations. Therefore, for an effective IPM program, selective insecticides or harmful pesticides to adult parasitoids could be used in the field, provided that the adults do not occur naturally and the chemical applications do not coincide with parasitoid releases.

  16. Adult Psychology.

    ERIC Educational Resources Information Center

    Bischof, Ledford J.

    This volume comprehensively reviews the research on the psychology of the middle aged (ages 40-65). Topics include the concept of maturity and maturation models, the measurement and influences of adult self image; marriage and sexual patterns; intergenerational relationships between and children; vocations and avocations (work, retirement, play,…

  17. ADULT EDUCATION OF MIGRANT ADULTS.

    ERIC Educational Resources Information Center

    BEAL, CATHERINE; AND OTHERS

    UNITS ON MIGRANT ADULT EDUCATION, AND A UNIT ON ORGANIZING INFORMAL GROUPS OF MIGRANT WOMEN TO DISCUSS MAINTAINING AND IMPROVING THEIR TEMPORARY HOMES, ARE PRESENTED. THE GOALS OF THE UNIT ON EDUCATION FOR MIGRANT MEN ARE ECONOMIC INDEPENDENCE, BETTER HEALTH AND WELL-BEING, AND BETTER HANDLING OF RESPONSIBILITIES. THE MAIN DIVISIONS OF THE…

  18. Panic Disorder among Adults

    MedlinePlus

    ... Autism Spectrum Disorder (ASD) Eating Disorders Among Adults - Anorexia Nervosa Eating Disorders Among Adults - Binge Eating Disorder ... Autism Spectrum Disorder (ASD) Eating Disorders Among Adults - Anorexia Nervosa Eating Disorders Among Adults - Binge Eating Disorder ...

  19. Obstructive sleep apnea - adults

    MedlinePlus

    Sleep apnea - obstructive - adults; Apnea - obstructive sleep apnea syndrome - adults; Sleep-disordered breathing - adults; OSA - adults ... When you sleep, all of the muscles in your body become more relaxed. This includes the muscles that help keep your ...

  20. Adult Development and Learning of Older Adults

    ERIC Educational Resources Information Center

    Roberson, Donald N., Jr.

    2005-01-01

    This summary of adult development covers a wide range of authors. Adult development is one way of understanding how the internal and external changes in our lives have an impact on learning. Of particular importance in this work are the developmental issues of older adults. I present various theories of adult development such as linear and…

  1. Preparing Educators of Adults.

    ERIC Educational Resources Information Center

    Grabowski, Stanley M.; And Others

    Model programs are described for two areas of adult education--the preparation of adult educators and the training conducted by adult educators. In Chapter One, Phyllis Caldwell reviews the literature concerning the preservice training of adult educators, concentrating on the competencies of adult education administrators and teachers. In Chapter…

  2. A specific interdomain interaction preserves the structural and binding properties of the ModA protein from the phytopathogen Xanthomonas citri domain interaction and transport in ModA.

    PubMed

    Santacruz-Perez, Carolina; Pegos, Vanessa Rodrigues; Honorato, Rodrigo V; Verli, Hugo; Lindahl, Erik; Barbosa, João Alexandre Ribeiro Gonçalves; Balan, Andrea

    2013-11-01

    The periplasmic-binding proteins in ATP-binding cassette systems (ABC Transporters) are responsible for the capture and delivery of ligands to their specific transporters, triggering a series of ATP-driven conformational changes that leads to the transport of the ligand. Structurally consisting of two lobes, the proteins change conformation after interaction with the ligand. The structure of the molybdate-binding protein (ModA) from Xanthomonas citri, bound to molybdate, was previously solved by our group and an interdomain interaction, mediated by a salt bridge between K127 and D59, apparently supports the binding properties and keeps the domains closed. To determinate the importance of this interaction, we built two ModA mutants, K127S and D59A, and analysed their functional and structural properties. Based on a set of spectroscopic experiments, crystallisation trials, structure determination and molecular dynamics (MD) simulations, we showed that the salt bridge is essential to maintain the structure and binding properties. Additionally, the MD simulations revealed that this mutant adopted a more compact structure that packed down the ligand-binding pocket. From the closed bound to open structure, the positioning of the helices forming the dipole and the salt bridge are essential to induce an intermediate state.

  3. Adults Need Vaccines, Too!

    MedlinePlus

    ... turn JavaScript on. Feature: Adult Vaccinations Adults Need Vaccines, Too! Past Issues / Summer 2015 Table of Contents ... of the millions of adults not receiving the vaccines you need? What vaccines do you need? All ...

  4. Brain tumor - primary - adults

    MedlinePlus

    ... Vestibular schwannoma (acoustic neuroma) - adults; Meningioma - adults; Cancer - brain tumor (adults) ... Primary brain tumors include any tumor that starts in the brain. Primary brain tumors can start from brain cells, ...

  5. Adult Day Care

    MedlinePlus

    ... Page Resize Text Printer Friendly Online Chat Adult Day Care Adult Day Care Centers are designed to provide care and ... adults who need assistance or supervision during the day. Programs offer relief to family members and caregivers, ...

  6. Adult Still's disease

    MedlinePlus

    Still's disease - adult; AOSD ... than 1 out of 100,000 people develop adult-onset Still's disease each year. It affects women more often than men. The cause of adult Still's disease is unknown. No risk factors for ...

  7. Adult Recruitment Practices.

    ERIC Educational Resources Information Center

    Kaufman, Juliet, Ed.; And Others

    Findings of an American College Testing Program 1981 survey on college recruitment of adult students are summarized, and 12 articles on adult recruitment are presented. Titles and authors are as follows: "Adult Recruitment Practices: A Report of a National Survey" (Patricia Spratt, Juliet Kaufmann, Lee Noel); "Three Programs for Adults in Shopping…

  8. Asymptomatic spread of huanglongbing and implications for disease control.

    PubMed

    Lee, Jo Ann; Halbert, Susan E; Dawson, William O; Robertson, Cecile J; Keesling, James E; Singer, Burton H

    2015-06-16

    Huanglongbing (HLB) is a bacterial infection of citrus trees transmitted by the Asian citrus psyllid Diaphorina citri. Mitigation of HLB has focused on spraying of insecticides to reduce the psyllid population and removal of trees when they first show symptoms of the disease. These interventions have been only marginally effective, because symptoms of HLB do not appear on leaves for months to years after initial infection. Limited knowledge about disease spread during the asymptomatic phase is exemplified by the heretofore unknown length of time from initial infection of newly developing cluster of young leaves, called flush, by adult psyllids until the flush become infectious. We present experimental evidence showing that young flush become infectious within 15 d after receiving an inoculum of Candidatus Liberibacter asiaticus (bacteria). Using this critical fact, we specify a microsimulation model of asymptomatic disease spread and intensity in a grove of citrus trees. We apply a range of psyllid introduction scenarios to show that entire groves can become infected with up to 12,000 psyllids per tree in less than 1 y, before most of the trees show any symptoms. We also show that intervention strategies that reduce the psyllid population by 75% during the flushing periods can delay infection of a full grove, and thereby reduce the amount of insecticide used throughout a year. This result implies that psyllid surveillance and control, using a variety of recently available technologies, should be used from the initial detection of invasion and throughout the asymptomatic period.

  9. Asymptomatic spread of huanglongbing and implications for disease control

    PubMed Central

    Lee, Jo Ann; Halbert, Susan E.; Dawson, William O.; Robertson, Cecile J.; Keesling, James E.; Singer, Burton H.

    2015-01-01

    Huanglongbing (HLB) is a bacterial infection of citrus trees transmitted by the Asian citrus psyllid Diaphorina citri. Mitigation of HLB has focused on spraying of insecticides to reduce the psyllid population and removal of trees when they first show symptoms of the disease. These interventions have been only marginally effective, because symptoms of HLB do not appear on leaves for months to years after initial infection. Limited knowledge about disease spread during the asymptomatic phase is exemplified by the heretofore unknown length of time from initial infection of newly developing cluster of young leaves, called flush, by adult psyllids until the flush become infectious. We present experimental evidence showing that young flush become infectious within 15 d after receiving an inoculum of Candidatus Liberibacter asiaticus (bacteria). Using this critical fact, we specify a microsimulation model of asymptomatic disease spread and intensity in a grove of citrus trees. We apply a range of psyllid introduction scenarios to show that entire groves can become infected with up to 12,000 psyllids per tree in less than 1 y, before most of the trees show any symptoms. We also show that intervention strategies that reduce the psyllid population by 75% during the flushing periods can delay infection of a full grove, and thereby reduce the amount of insecticide used throughout a year. This result implies that psyllid surveillance and control, using a variety of recently available technologies, should be used from the initial detection of invasion and throughout the asymptomatic period. PMID:26034273

  10. The HD-GYP domain of RpfG mediates a direct linkage between the Rpf quorum-sensing pathway and a subset of diguanylate cyclase proteins in the phytopathogen Xanthomonas axonopodis pv citri.

    PubMed

    Andrade, Maxuel O; Alegria, Marcos Castanheira; Guzzo, Cristiane R; Docena, Cassia; Rosa, Maria Claudia Pareda; Ramos, Carlos H I; Farah, Chuck S

    2006-10-01

    Bacteria use extracellular levels of small diffusible autoinducers to estimate local cell-density (quorum-sensing) and to regulate complex physiological processes. The quorum-sensing signal transduction pathway of Xanthomonas spp. phytopathogens has special features that distinguish it from that of other pathogens. This pathway consists of RpfF, necessary for the production of the unique autoinducer 'diffusible signalling factor' (DSF), and RpfC and RpfG, a two-component system necessary for the DSF-dependent production of extracellular pathogenicity factors and cellular dispersion. Yeast two-hybrid and direct in vitro assays were used to identify interactions involving the Rpf group of proteins. We show that RpfC, a protein consisting of N-terminal transmembrane, histidine kinase, response-regulator and C-terminal histidine phosphotransfer domains interacts with both RpfG, a protein consisting of an N-terminal response regulator domain and a C-terminal HD-GYP domain, and with RpfF. We also show that RpfC interacts with the only known homologue of 'conditioned medium factor', which is involved in quorum-sensing in Dictyostelium discoideum under conditions of nutritional stress. Furthermore, RpfCG is shown to interact with a second two-component system made up of NtrB and NtrC homologues. Finally we show that the recently characterized HD-GYP phosphodiesterase domain of RpfG interacts directly with diguanylate cyclase GGDEF domain-containing proteins coded by the Xanthomonas axonopodis pv. citri genome, which in other bacteria produce cyclic diGMP, an important second messenger involved in the regulation of complex bacterial processes including biofilm production, virulence and motility. These results demonstrate a direct physical linkage between quorum-sensing and cyclic diGMP signalling pathways in bacteria.

  11. Reclassification of Xanthomonas campestris pv. citri (ex Hasse 1915) Dye 1978 forms A, B/C/D, and E as X. smithii subsp. citri (ex Hasse) sp. nov. nom. rev. comb. nov., X. fuscans subsp. aurantifolii (ex Gabriel 1989) sp. nov. nom. rev. comb. nov., and X. alfalfae subsp. citrumelo (ex Riker and Jones) Gabriel et al., 1989 sp. nov. nom. rev. comb. nov.; X. campestris pv malvacearum (ex smith 1901) Dye 1978 as X. smithii subsp. smithii nov. comb. nov. nom. nov.; X. campestris pv. alfalfae (ex Riker and Jones, 1935) dye 1978 as X. alfalfae subsp. alfalfae (ex Riker et al., 1935) sp. nov. nom. rev.; and "var. fuscans" of X. campestris pv. phaseoli (ex Smith, 1987) Dye 1978 as X. fuscans subsp. fuscans sp. nov.

    PubMed

    Schaad, Norman W; Postnikova, Elena; Lacy, George H; Sechler, Aaron; Agarkova, Irina; Stromberg, Paul E; Stromberg, Verlyn K; Vidaver, Anne K

    2005-08-01

    Bacterial canker of citrus is a serious disease of citrus worldwide. Five forms of the disease have been described, cankers "A", "B", "C", "D", and "E". Although considerable genetic diversity has been described among the causal agents of the five forms of citrus canker and supports multiple taxons, the causal agents currently are classified as pathovars citri ("A"), aurantifolii ("B/C/D") and citrumelo ("E") of a single species, Xanthomonas campestris pv. citri (or X. axonopodis pv. citri). To determine the taxonomic relatedness among strains of X. campestris pv. citri, we conducted DNA-DNA relatedness assays, sequenced the 16S-23S intergenic spacer (ITS) regions, and performed amplified fragment length polymorphism (AFLP) analysis, using 44 strains representative of the five recognized forms of citrus canker. Under stringent DNA reassociation conditions (Tm - 15 degrees C), three distinct genotypes of citrus pathogens were revealed: taxon I included all "A" strains; taxon II contained all "B", "C", and "D" strains; and taxon III contained all "E" strains. The three citrus taxa showed less than 50% (mean) DNA-DNA relatedness to each other and less than 30% (mean) to X. campestris pv. campestris and X. axonopodis pv. axonopodis. Taxa I and II strains share over 70% DNA relatedness to X. campestris pv. malvacearum and X. campestris pv. phaseoli var. fuscans, respectively (at Tm - 15 degrees C). Taxon III strains share 70% relatedness to X. campestris pv. alfalfae. Previous and present phenotypic data support these DNA reassociation data. Taxon II strains grow more slowly on agar media than taxa I and III strains. Taxa I and III strains utilize maltose, and liquefy gelatin whereas taxon II strains do not. Taxon I strains hydrolyze pectate (pH 7.0) whereas Taxon II strains do not. Taxon III strains utilize raffinose whereas Taxon I strains do not. Each taxon can be differentiated by serology and pathogenicity. We propose taxa I, II, and III citrus strains be named

  12. Clueless? Adult Mysteries with Young Adult Appeal.

    ERIC Educational Resources Information Center

    Charles, John; Morrison, Joanna

    1997-01-01

    Presents a list of adult mystery titles for young adult readers. Includes first titles in a series (for reading in order); new and lesser-known mystery authors' works are the focus. Annotations include plot summary. The rest of each annotation is for professional use (includes date and name of award bestowed). (AEF)

  13. Young Adult Literature for Young Adult Males.

    ERIC Educational Resources Information Center

    Gill, Sam D.

    1999-01-01

    Argues that young adult literature can play a significant role in the emotional and mental health of an adolescent as well as help young males become more literate. Offers a 19-item annotated list of young adult novels with male protagonists, sorted by themes: nature and adventure stories, sports stories, genre stories, historical stories, and…

  14. Depression in Older Adults

    ERIC Educational Resources Information Center

    Stickle, Fred; Onedera, Jill D.

    2006-01-01

    The purpose of this article is to address selected aspects of depression in older adults. Specifically, symptoms, risk factors, diagnosis, and interventions for depression in older adults are reviewed.

  15. Immunization Schedules for Adults

    MedlinePlus

    ... ACIP Vaccination Recommendations Why Immunize? Vaccines: The Basics Immunization Schedules for Adults in Easy-to-read Formats ... previous immunizations. View or Print a Schedule Recommended Immunizations for Adults (19 Years and Older) by Age ...

  16. Adult Education Update

    ERIC Educational Resources Information Center

    Hall, Clyde W.

    1975-01-01

    Summarized are speeches dealing with adult education's stiff-necked adherence to middle-class values; the need for upgraded management skills; and a report of a study of adult education in area vocational schools in Georgia. (Author/AJ)

  17. Adult Education in Sweden.

    ERIC Educational Resources Information Center

    Miller, Harry; And Others

    Folk high schools, study circles, labor market training, union education, and municipal adult schools are the major providers of adult education in Sweden. For the most part, these programs are financed by the government and are tuition free. Folk high schools, which are the oldest type, were founded to provide young adults with a general civic…

  18. The Adult Experience.

    ERIC Educational Resources Information Center

    Belsky, Janet

    The 14 chapters of this textbook chronicle adult development from youth through old age, emphasizing both research and interviews with adults at various stages in their lives. Topics covered include the following: (1) the academic field of adult development; (2) theories and research methods; (3) aging and disease prevention; (4) sexuality and…

  19. Adult Survival Skills Assessment.

    ERIC Educational Resources Information Center

    Walsko, Gregory M.

    The purpose of this instrument is to supplement data from the Adult Basic Learning Examination in assessing the functional level of adults in daily situations. It may also be used as a teaching tool for adults requesting tutoring in specific concepts and skills presented in the instrument. This instrument is an informal assessment instrument and…

  20. Kids Who Outwit Adults.

    ERIC Educational Resources Information Center

    Seita, John R.; Brendtro, Larry K.

    Kids who distrust adults are highly skilled at hiding their real nature and resisting change. Most adults shun such youths or get mired in conflict with them. Punitive get tough practices as well as traditional flaw-fixing treatment are reactive strategies that often drive these youths further from adult bonds and reinforce oppositional and…

  1. Urbanization and Adult Education

    ERIC Educational Resources Information Center

    Short, W. Fisher

    1974-01-01

    The impact of urbanization, the main tasks facing the adult educator in an urban context, identifying the casualties of urbanization, recognizing and dealing with social deprivation, and the various agencies involved in adult education are relevant considerations for adult educators. (MW)

  2. Dimensions of Adult Learning

    ERIC Educational Resources Information Center

    Foley, Griff, Ed.

    2004-01-01

    This broad introduction to adult and postcompulsory education offers an overview of the field for students, adult educators and workplace trainers. The book establishes an analytical framework to emphasize the nature of learning and agency of learners; examines the core knowledge and skills that adult educators need; discusses policy, research and…

  3. Adult Learning: A Reader.

    ERIC Educational Resources Information Center

    Sutherland, Peter, Ed.

    This book on adult learning is divided into six sections. Section 1, Cognitive Processes, includes the following chapters: "Cognitive Processes: Contemporary Paradigms of Learning" (Jack Mezirow); "Information Processing, Memory, Age and Adult Learning" (Gillian Boulton-Lewis); "Adult Learners' Metacognitive Behaviour in Higher Education" (Barry…

  4. Adult Education in Israel.

    ERIC Educational Resources Information Center

    Kirmayer, Paul, Ed.; And Others

    This volume contains 13 articles that reflect the development of adult education in Israel during recent years. The material relates to the principal areas with which the Division of Adult Education deals: formal and nonformal education for adults, language and cultural absorption of new immigrants, and training of facilitators for parental…

  5. Adults Role in Bullying

    ERIC Educational Resources Information Center

    Notar, Charles E.; Padgett, Sharon

    2013-01-01

    Do adults play a role in bullying? Do parents, teachers, school staff, and community adult leaders influence bullying behavior in children and teenagers? This article will focus on research regarding all adults who have almost daily contact with children and teens and their part in how bullying is identified, addressed, and prevented. This article…

  6. Adult Education in Greece

    ERIC Educational Resources Information Center

    Kokkos, Alexios

    2008-01-01

    The central aim of this article is to analyse the current situation of adult education in Greece. The article focuses on the following points: (a) the degree of participation in programmes of continuing professional training and general adult education courses, (b) the quality and the outcomes of the adult education provision in Greece, and (c)…

  7. Adult Competency Education Profile.

    ERIC Educational Resources Information Center

    Bureau of Occupational and Adult Education (DHEW/OE), Washington, DC. Div. of Adult Education.

    A compilation of abstracts of 120 current Adult Performance Level (APL) and Adult Competency Education (ACE) federally supported projects being conducted in 34 States and the District of Columbia, this project profile was developed for adult and secondary education administrators, teachers, and program developers who are beginning or are currently…

  8. Adult Competency Education Resources.

    ERIC Educational Resources Information Center

    Bureau of Occupational and Adult Education (DHEW/OE), Washington, DC. Div. of Adult Education.

    A compilation of brief descriptions of 20 current resources for Adult Performance Level (APL) and Adult Competency Education (ACE) programs, this guide was developed for adult and secondary education administrators, teachers, and program developers who are beginning or are already involved with APL/ACE programs. Each citation contains information…

  9. Adult Academy Volunteer Manual.

    ERIC Educational Resources Information Center

    Cora, Marie T., Ed.; Wood, Nicole R., Ed.

    This handbook was written specifically for volunteer tutors but is appropriate for teachers, student interns, coordinators, and others working with Adult Basic Education (ABE) and English-as-a-Second-Language (ESL) adult learners. It presents an overview of adult and non-traditional education models, some principles of reading and writing, a…

  10. Canadian Adult Basic Education.

    ERIC Educational Resources Information Center

    Brooke, W. Michael, Comp.

    "Trends," a publication of the Canadian Association for Adult Education, is a collection of abstracts on selected subjects affecting adult education; this issue is on adult basic education (ABE). It covers teachers and teacher training, psychological factors relating to the ABE teacher and students, manuals for teachers, instructional…

  11. Young Adult Services Manual.

    ERIC Educational Resources Information Center

    Boegen, Anne, Ed.

    Designed to offer guidelines, ideas and help to those who provide library service to young adults, this manual includes information about the provision of young adult (YA) services in six sections. The first section, which addresses planning and administration, includes a definition of a young adult and a checklist for determining community needs…

  12. Adult Educators' Core Competences

    ERIC Educational Resources Information Center

    Wahlgren, Bjarne

    2016-01-01

    Which competences do professional adult educators need? This research note discusses the topic from a comparative perspective, finding that adult educators' required competences are wide-ranging, heterogeneous and complex. They are subject to context in terms of national and cultural environment as well as the kind of adult education concerned…

  13. An Adult ESL Curriculum.

    ERIC Educational Resources Information Center

    South Carolina Literacy Resource Center, Columbia.

    This curriculum framework for adult literacy was written by 21 South Carolina adult English-as-a-Second-Language (ESL) instructors, as submitted to the South Carolina Literacy Resource Center. It is based on current theories in the fields of adult education and second language acquisition and is designed to be flexible so that it may be adapted to…

  14. Obsessive Compulsive Disorder among Adults

    MedlinePlus

    ... Autism Spectrum Disorder (ASD) Eating Disorders Among Adults - Anorexia Nervosa Eating Disorders Among Adults - Binge Eating Disorder ... Autism Spectrum Disorder (ASD) Eating Disorders Among Adults - Anorexia Nervosa Eating Disorders Among Adults - Binge Eating Disorder ...

  15. Extracts of Immature Orange (Aurantii fructus immaturus) and Citrus Unshiu Peel (Citri unshiu pericarpium) Induce P-Glycoprotein and Cytochrome P450 3A4 Expression via Upregulation of Pregnane X Receptor.

    PubMed

    Okada, Naoto; Murakami, Aki; Urushizaki, Shiori; Matsuda, Misa; Kawazoe, Kazuyoshi; Ishizawa, Keisuke

    2017-01-01

    P-glycoprotein (P-gp) and cytochrome P450 3A4 (CYP3A4) are expressed in the intestine and are associated with drug absorption and metabolism. Pregnane X receptor (PXR) is the key molecule that regulates the expression of P-gp and CYP3A4. Given that PXR activity is regulated by a variety of compounds, it is possible that unknown PXR activators exist among known medicines. Kampo is a Japanese traditional medicine composed of various natural compounds. In particular, immature orange [Aurantii fructus immaturus (IO)] and citrus unshiu peel [Citri unshiu pericarpium (CP)] are common ingredients of kampo. A previous study reported that kampo containing IO or CP decreased the blood concentration of concomitant drugs via upregulation of CYP3A4 although the mechanism was unclear. Some flavonoids are indicated to alter P-gp and CYP3A4 activity via changes in PXR activity. Because IO and CP include various flavonoids, we speculated that the activity of P-gp and CYP3A4 in the intestine may be altered via changes in PXR activity when IO or CP is administered. We tested this hypothesis by using LS180 intestinal epithelial cells. The ethanol extract of IO contained narirutin and naringin, and that of CP contained narirutin and hesperidin. Ethanol extracts of IO and CP induced P-gp, CYP3A4, and PXR expression. The increase of P-gp and CYP3A4 expression by the IO and CP ethanol extracts was inhibited by ketoconazole, an inhibitor of PXR activation. The ethanol extract of IO and CP decreased the intracellular concentration of digoxin, a P-gp substrate, and this decrease was inhibited by cyclosporine A, a P-gp inhibitor. In contrast, CP, but not IO, stimulated the metabolism of testosterone, a CYP3A4 substrate, and this was inhibited by a CYP3A4 inhibitor. These findings indicate that the ethanol extract of IO and CP increased P-gp and CYP3A4 expression via induction of PXR protein. Moreover, this induction decreased the intracellular substrate concentration.

  16. Extracts of Immature Orange (Aurantii fructus immaturus) and Citrus Unshiu Peel (Citri unshiu pericarpium) Induce P-Glycoprotein and Cytochrome P450 3A4 Expression via Upregulation of Pregnane X Receptor

    PubMed Central

    Okada, Naoto; Murakami, Aki; Urushizaki, Shiori; Matsuda, Misa; Kawazoe, Kazuyoshi; Ishizawa, Keisuke

    2017-01-01

    P-glycoprotein (P-gp) and cytochrome P450 3A4 (CYP3A4) are expressed in the intestine and are associated with drug absorption and metabolism. Pregnane X receptor (PXR) is the key molecule that regulates the expression of P-gp and CYP3A4. Given that PXR activity is regulated by a variety of compounds, it is possible that unknown PXR activators exist among known medicines. Kampo is a Japanese traditional medicine composed of various natural compounds. In particular, immature orange [Aurantii fructus immaturus (IO)] and citrus unshiu peel [Citri unshiu pericarpium (CP)] are common ingredients of kampo. A previous study reported that kampo containing IO or CP decreased the blood concentration of concomitant drugs via upregulation of CYP3A4 although the mechanism was unclear. Some flavonoids are indicated to alter P-gp and CYP3A4 activity via changes in PXR activity. Because IO and CP include various flavonoids, we speculated that the activity of P-gp and CYP3A4 in the intestine may be altered via changes in PXR activity when IO or CP is administered. We tested this hypothesis by using LS180 intestinal epithelial cells. The ethanol extract of IO contained narirutin and naringin, and that of CP contained narirutin and hesperidin. Ethanol extracts of IO and CP induced P-gp, CYP3A4, and PXR expression. The increase of P-gp and CYP3A4 expression by the IO and CP ethanol extracts was inhibited by ketoconazole, an inhibitor of PXR activation. The ethanol extract of IO and CP decreased the intracellular concentration of digoxin, a P-gp substrate, and this decrease was inhibited by cyclosporine A, a P-gp inhibitor. In contrast, CP, but not IO, stimulated the metabolism of testosterone, a CYP3A4 substrate, and this was inhibited by a CYP3A4 inhibitor. These findings indicate that the ethanol extract of IO and CP increased P-gp and CYP3A4 expression via induction of PXR protein. Moreover, this induction decreased the intracellular substrate concentration. PMID:28270768

  17. Adult Education Regional Planning

    ERIC Educational Resources Information Center

    California Community Colleges, Chancellor's Office, 2015

    2015-01-01

    For more than one hundred and fifty years, until 2008, California was an undisputed national leader in its commitment to adult education. The state's investment in adult learners topped $750 million, a sum greater than the combined total of every other state in the nation. However, for the past several years recession and fiscal crisis have left…

  18. Young Adult Library Services.

    ERIC Educational Resources Information Center

    The Bookmark, 1985

    1985-01-01

    Eight articles in this Spring 1985 issue of The Bookmark focus on young adult library services. In addition to these thematic articles, an introduction and three reports are presented. The issue contains: (1) "In Perspective" (E. J. Josey); (2) "Young Adult Literature in the 1980's--Awesome!" (Ellin Chu); (3) "Young Adult…

  19. Toward Transpersonal Adult Development

    ERIC Educational Resources Information Center

    Boucouvalas, Marcie

    2016-01-01

    As a foundation for discussing transpersonal adult development, the author traces her trajectory, involvement in, and contribution to the modern transpersonal movement and her introduction of it to the adult learning literature, beginning during the early 1980s. Highlighted are the transpersonal domain and a differentiation between transpersonal…

  20. Adult Day Services

    MedlinePlus

    A Smart Choice Adult Day Services Comparison At-a-Glance 1 Adult Day Services Assisted Living Home Care Nursing Homes Live at home with family ... supervision Nursing care available as needed during the day Flexibility to receive care only on days when ...

  1. Adult Tech Prep.

    ERIC Educational Resources Information Center

    Schaad, Donna

    For over 2 years, Blak Hawk College (Illinois) has provided high school equivalency (GED) candidates and recipients, older returning students, and underprepared high school graduates with a Tech Prep curriculum to give them the skills to make the transition from adult basic education to college or work. The Adult Tech Prep (ATP) core curriculum…

  2. Authenticity in Adult Learning

    ERIC Educational Resources Information Center

    Ashton, Sam

    2010-01-01

    This paper is concerned with the relationship between authenticity and adult learning and prompted by some studies in which adult "authentic learning" is a central concept. The implication revealed by them is that real-worldness of learning contexts, learning content and learning tasks is perceived as conferring authenticity on learning. Here,…

  3. Adult Learning and Education

    ERIC Educational Resources Information Center

    Rubenson, Kjell, Ed.

    2011-01-01

    As individuals and societies try to respond to fundamental economic and social transformation, the field of adult learning and education is rapidly getting increased attention and new topics for research on adult learning have emerged. This collection of articles from the International Encyclopedia of Education 3e offers practitioners and…

  4. Today's Adult Students

    ERIC Educational Resources Information Center

    Reese, Susan

    2012-01-01

    Who are the adult students in career and technical education (CTE) today? There is not one simple answer to that question. Some are young with little life experience, while others are returning to the workforce and learning new skills to reinvent themselves. Whatever the case, educating adult students is an integral part of ACTE's mission, and the…

  5. Adult Literacy in Zanzibar.

    ERIC Educational Resources Information Center

    Saadat, Ahmed H.

    The philosophy behind adult literacy in Zanzibar is that adult literacy is a process whereby the illiterate is empowered to become aware of his or her potential. Literacy activities emphasize a relation to work, sometimes known as functional literacy. Specific objectives of literacy programs are to improve living conditions, impart self-reliant…

  6. Adult Vocational Trajectory.

    ERIC Educational Resources Information Center

    Riverin-Simard, Danielle

    1990-01-01

    Proposes a "spatial-temporal" model conceiving adult vocational development as a complex and constant readjustment in always changing perception of personal space-time, based on interviews of 786 adults. Presents two propositions of this model: the continuous alternation between states of instability and interaction of influences.…

  7. Counseling Adult Adoptees

    ERIC Educational Resources Information Center

    Corder, Kate

    2012-01-01

    This review presents various resources about working with adult adoptees in order to inform counselors in their practice. Topics covered include basics of adoption, including types of adoption and adoption statistics; possible issues adult adoptees may face; and suggestions and implications for counselors. The article addresses some of the serious…

  8. Alternative Programming for Adults.

    ERIC Educational Resources Information Center

    Flint, Thomas A.; Frey, Ruth

    2003-01-01

    The Council for Adult and Experiential Learning is currently cataloguing alternative programming features that are most effective with adult students in a best practices inventory organized around a framework of high-level descriptive principles of effectiveness. This chapter identifies a few interesting features from a quick survey of this…

  9. Adult Education and Development.

    ERIC Educational Resources Information Center

    Hinzen, Heribert, Ed.

    2002-01-01

    This document contains 19 papers on adult education and development worldwide. The following papers are included: "Editorial" (Heribert Hinzen); "Lifelong Learning in Europe: Moving towards EFA (Dakar Framework for Action on Education for All) Goals and the CONFINTEA V Agenda" (Sofia Conference on Adult Education);…

  10. Adult Education in Finland

    ERIC Educational Resources Information Center

    Szekely, Radu

    2006-01-01

    Ever since the first ideas of national independence appeared in Finland, adult education has played an essential role in shaping the destiny of the Finns. With a history of almost 130 years, during which it has continuously increased in quality and quantity, the Finnish adult education system has ensured that Finland stays among the most…

  11. Financing of Adult Education

    ERIC Educational Resources Information Center

    Archer, David

    2007-01-01

    The 2008 EFA Global Monitoring Report recognises adult literacy as the most neglected of the EFA goals. It is neglected most obviously in respect of the financial allocations made by governments and donors. This shortage of financing creates a dangerous situation in which adult educators seek to convince politicians to invest, based on false…

  12. Gender Dysphoria in Adults.

    PubMed

    Zucker, Kenneth J; Lawrence, Anne A; Kreukels, Baudewijntje P C

    2016-01-01

    Gender dysphoria (GD), a term that denotes persistent discomfort with one's biologic sex or assigned gender, replaced the diagnosis of gender identity disorder in the Diagnostic and Statistical Manual of Mental Disorders in 2013. Subtypes of GD in adults, defined by sexual orientation and age of onset, have been described; these display different developmental trajectories and prognoses. Prevalence studies conclude that fewer than 1 in 10,000 adult natal males and 1 in 30,000 adult natal females experience GD, but such estimates vary widely. GD in adults is associated with an elevated prevalence of comorbid psychopathology, especially mood disorders, anxiety disorders, and suicidality. Causal mechanisms in GD are incompletely understood, but genetic, neurodevelopmental, and psychosocial factors probably all contribute. Treatment of GD in adults, although largely standardized, is likely to evolve in response to the increasing diversity of persons seeking treatment, demands for greater client autonomy, and improved understanding of the benefits and limitations of current treatment modalities.

  13. Metabolomic comparative analysis of the phloem sap of curry leaf tree (Bergera koenegii), orange jasmine (Murraya paniculata), and Valencia sweet orange (Citrus sinensis) supports their differential responses to Huanglongbing.

    PubMed

    Killiny, Nabil

    2016-11-01

    Orange jasmine, Murraya paniculata and curry leaf tree, Bergera koenegii are alternative hosts for Diaphorina citri, the vector of Candidatus Liberibacter asiaticus (CLas), the pathogen of huanglongbing (HLB) in citrus. D. citri feeds on the phloem sap where CLas grows. It has been shown that orange jasmine was a better host than curry leaf tree to D. citri. In addition, CLas can infect orange jasmine but not curry leaf tree. Here, we compared the phloem sap composition of these 2 plants to the main host, Valencia sweet orange, Citrus sinensis. Phloem sap was analyzed by gas chromatography-mass spectrometry after trimethylsilyl derivatization. Orange jasmine was the highest in proteinogenic, non-proteinogenic amino acids, organic acids, as well as total metabolites. Valencia was the highest in mono- and disaccharides, and sugar alcohols. Curry leaf tree was the lowest in most of the metabolites as well as total metabolites. Interestingly, malic acid was high in Valencia and orange jasmine but was not detected in the curry leaf. On the other hand, tartaric acid which can prevent the formation of malic acid in Krebs cycle was high in curry leaf. The nutrient inadequacy of the phloem sap in curry leaf tree, especially the amino acids could be the reason behind the longer life cycle and the low survival of D. citri and the limitation of CLas growth on this host. Information obtained from this study may help in cultivation of CLas and development of artificial diet for rearing of D. citri.

  14. Metabolic Interplay between the Asian Citrus Psyllid and Its Profftella Symbiont: An Achilles’ Heel of the Citrus Greening Insect Vector

    PubMed Central

    Ramsey, John S.; Johnson, Richard S.; Hoki, Jason S.; Kruse, Angela; Mahoney, Jaclyn; Hilf, Mark E.; Hunter, Wayne B.; Hall, David G.; Schroeder, Frank C.; MacCoss, Michael J.; Cilia, Michelle

    2015-01-01

    ‘Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease, is transmitted by Diaphorina citri, the Asian citrus psyllid. Interactions among D. citri and its microbial endosymbionts, including ‘Candidatus Profftella armatura’, are likely to impact transmission of CLas. We used quantitative mass spectrometry to compare the proteomes of CLas(+) and CLas(-) populations of D. citri, and found that proteins involved in polyketide biosynthesis by the endosymbiont Profftella were up-regulated in CLas(+) insects. Mass spectrometry analysis of the Profftella polyketide diaphorin in D. citri metabolite extracts revealed the presence of a novel diaphorin-related polyketide and the ratio of these two polyketides was changed in CLas(+) insects. Insect proteins differentially expressed between CLas(+) and CLas(-) D. citri included defense and immunity proteins, proteins involved in energy storage and utilization, and proteins involved in endocytosis, cellular adhesion, and cytoskeletal remodeling which are associated with microbial invasion of host cells. Insight into the metabolic interdependence between the insect vector, its endosymbionts, and the citrus greening pathogen reveals novel opportunities for control of this disease, which is currently having a devastating impact on citrus production worldwide. PMID:26580079

  15. Depression in Older Adults

    PubMed Central

    Fiske, Amy; Wetherell, Julie Loebach; Gatz, Margaret

    2010-01-01

    Depression is less prevalent among older adults than among younger adults but can have serious consequences. Over half of cases represent a first onset in later life. Although suicide rates in the elderly are declining, they are still higher than in younger adults and more closely associated with depression. Depressed older adults are less likely to endorse affective symptoms and more likely to display cognitive changes, somatic symptoms, and loss of interest than are younger adults. Risk factors leading to the development of late life depression likely comprise complex interactions among genetic vulnerabilities, cognitive diathesis, age-associated neurobiological changes, and stressful events. Insomnia is an often overlooked risk factor for late life depression. We suggest that a common pathway to depression in older adults, regardless of which predisposing risks are most prominent, may be curtailment of daily activities. Accompanying self-critical thinking may exacerbate and maintain a depressed state. Offsetting the increasing prevalence of certain risk factors in late life are age-related increases in psychological resilience. Other protective factors include higher education and socioeconomic status, engagement in valued activities, and religious or spiritual involvement. Treatments including behavioral therapy, cognitive behavioral therapy, cognitive bibliotherapy, problem-solving therapy, brief psychodynamic therapy, and life review/reminiscence therapy are effective but too infrequently used with older adults. Preventive interventions including education for individuals with chronic illness, behavioral activation, cognitive restructuring, problem-solving skills training, group support, and life review have also received support. PMID:19327033

  16. Mosquito, adult (image)

    MedlinePlus

    This illustration shows an adult southern house mosquito. This mosquito feeds on blood and is the carrier of many diseases, such as encephalitis, West Nile, dengue fever, yellow fever, and others. ( ...

  17. Older Adults and Alcohol

    MedlinePlus

    ... Alcohol Exposure Support & Treatment Alcohol Policy Special Populations & Co-occurring Disorders Publications & Multimedia Brochures & Fact Sheets NIAAA ... are here Home » Alcohol & Your Health » Special Populations & Co-occurring Disorders » Older Adults In this Section Underage ...

  18. Speech impairment (adult)

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003204.htm Speech impairment (adult) To use the sharing features on ... 2017, A.D.A.M., Inc. Duplication for commercial use must be authorized in writing by ADAM ...

  19. Motivation and Adult Education

    ERIC Educational Resources Information Center

    Veeraraghavan, J.

    1974-01-01

    The paper examines the role of adult education and the contribution it can make to the solution of current problems in developing countries, particularly the problems of economic under-development and over-population. (Author/AG)

  20. Motivation and Adult Education.

    ERIC Educational Resources Information Center

    Taylor, J. Rodney

    1982-01-01

    The author reviews theories of human motivation: Lewin's force field analysis, Skinner's operant reinforcement theory, and Maslow's hierarchy of needs. He then extracts the implications of these theories for adult learning. SK)

  1. Older Adults and Depression

    MedlinePlus

    ... find more information? Reprints Share Older Adults and Depression Download PDF Download ePub Order a free hardcopy ... depression need treatment to feel better. Types of Depression There are several types of depression. The most ...

  2. Young Adult Books.

    ERIC Educational Resources Information Center

    Epstein, Connie C.

    1987-01-01

    Considers the similarities between science fiction writing and young adult literature, and points out that several well-known authors, such as Robert Heinlein and Jane Yolen, write in both genres. (NKA)

  3. Cardiac imaging in adults

    SciTech Connect

    Jaffe, C.C.

    1987-01-01

    This book approaches adult cardiac disease from the correlative imaging perspective. It includes chest X-rays and angiographs, 2-dimensional echocardiograms with explanatory diagrams for clarity, plus details on digital radiology, nuclear medicine techniques, CT and MRI. It also covers the normal heart, valvular heart disease, myocardial disease, pericardial disease, bacterial endocarditis, aortic aneurysm, cardiac tumors, and congenital heart disease of the adult. It points out those aspects where one imaging technique has significant superiority.

  4. Adult educators' core competences

    NASA Astrophysics Data System (ADS)

    Wahlgren, Bjarne

    2016-06-01

    Which competences do professional adult educators need? This research note discusses the topic from a comparative perspective, finding that adult educators' required competences are wide-ranging, heterogeneous and complex. They are subject to context in terms of national and cultural environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or "core" requirements, organising them into four thematic subcategories: (1) communicating subject knowledge; (2) taking students' prior learning into account; (3) supporting a learning environment; and (4) the adult educator's reflection on his or her own performance. At the end of his analysis of different competence profiles, the author notes that adult educators' ability to train adult learners in a way which then enables them to apply and use what they have learned in practice (thus performing knowledge transfer) still seems to be overlooked.

  5. [Orthodontic treatment for adults].

    PubMed

    Kuitert, R B

    2000-04-01

    The number of adults undergoing orthodontic treatment has increased strongly and the average age that adult patients undergo orthodontic treatment increased steadily although 3/4 is still younger than 27 years. In adults the facial skeletal pattern can only be changed in a very confined way, consequently in case of an abnormal skeletal pattern one has to choose between a combined orthodontic-surgical approach (which is the case in 18% of the patients) and a compromised orthodontic treatment, if necessary combined with other disciplines. It is still controversial whether tooth movement in adults is slower and more difficult than in adolescents. The same holds true for the risk for loss of periodontal support, for root resorption, for gnathologic problems and for relapse. As related to these variables there appears to be a large individual variation. Many adults show one or more problems in their dentition that may influence their orthodontic treatment. About 60% of the adult patients need a multidisciplinary approach. The development of implantology and of bone regeneration and bone grafting has lead to more combined treatments. The risks of such complex treatment plans are generally larger than those for more simple kinds of treatment. A very careful treatment planning and good communication between the different specialists is essential. Moreover the treatment plan with all its (dis)advantages has to be extensively discussed with the patient.

  6. The State of Adult Education

    ERIC Educational Resources Information Center

    Fleming, Ted

    2004-01-01

    In this paper, the author looks at the state of adult education in Ireland. He is suggesting that the state here means both the condition in which one now finds adult education and the role of the Irish State in adult education. He briefly outlines some recent developments in adult education, makes some critical comments on the state of adult…

  7. The ABC's of Adult Ed

    ERIC Educational Resources Information Center

    Roehrig, Lucy

    2010-01-01

    According to the 2003 National Assessment of Adult Literacy, it is estimated that 93 million adults in the United States have basic or below basic literacy skills. Those individuals found most lacking in literacy skills were adults living in poverty, adults lacking a high school diploma, seniors and the elderly aged 65 and older, the more than one…

  8. Designing an Adult Education Program.

    ERIC Educational Resources Information Center

    Rand, Margaret

    Intended for planners of adult education curriculums, this literature review explains the concepts involved in designing an adult education program, provides information about the roles of the people involved in the adult education process, cites some program planning models, and applies the program planning principles to an Adult Basic Education…

  9. The Adult Learner: Four Aspects.

    ERIC Educational Resources Information Center

    Lucas, John A., Ed.

    1986-01-01

    Topics concerning the adult learner that are relevant to institutional researchers are addressed in four articles: marketing, predicting success for adult students, enrollment projection, and follow-up studies of adult learners. In "Institutional Research in Support of Marketing the Adult Student," Lydia Jurand notes the importance of…

  10. Rich Environments for Adult Learners

    ERIC Educational Resources Information Center

    Bentham, Renee

    2008-01-01

    Unaware of the messages a bare adult learning environment sends and its effect on adult learners, a trainer attends an intensive Reggio Emilia course and learns that the physical environment is the "third teacher"--for adults as well as for children. Using principles of Reggio, she offers suggestions for enhancing adult learning spaces and…

  11. Adult-onset Atopic Dermatitis

    PubMed Central

    Kanwar, Amrinder Jit

    2016-01-01

    Adult-onset atopic dermatitis is still an under recognized condition as there are only few studies regarding this entity. As compared to childhood onset atopic dermatitis, clinical features of adult onset atopic dermatitis are still not categorized. Adult atopic dermatitis can present for the first time in adult age with atypical morphology or may progress from childhood onset. This article reviews the characteristic clinical features of adult atopic dermatitis, associated risk factors and management. PMID:27904186

  12. Adult onset retinoblastoma

    PubMed Central

    Sengupta, Sabyasachi; Pan, Utsab; Khetan, Vikas

    2016-01-01

    Retinoblastoma (RB) is the most common primary malignant intraocular tumor of childhood presenting usually before 5 years of age. RB in adults older than 20 years is extremely rare. A literature search using PubMed/PubMed Central, Scopus, Google Scholar, EMBASE, and Cochrane databases revealed only 45 cases till date. Over the past decade, there has been a significant increase in the number of such reports, indicating heightened level of suspicion among ophthalmologists. Compared to its pediatric counterpart, adult onset RB poses unique challenges in diagnosis and treatment. This article summarizes available literature on adult onset RB and its clinical and pathologic profile, genetics, association with retinocytoma, diagnostics, treatment, and outcomes. PMID:27609158

  13. Adult Seborrheic Dermatitis

    PubMed Central

    2011-01-01

    Seborrheic dermatitis is a common chronic-recurrent inflammatory disorder that most commonly affects adults; however, a more transient infantile form also occurs. The definitive cause of seborrheic dermatitis is unknown. However, proliferation of Malassezia species has been described as a contributing factor. The adult form of seborrheic dermatitis affects up to approximately five percent of the general population. The disorder commonly affects the scalp, face, and periauricular region, with the central chest, axillae, and genital region also involved in some cases. Pruritus is not always present and is relatively common, especially with scalp disease. A variety of treatments are available including topical corticosteroids, topical antifungal agents, topical calcineurin inhibitors, and more recently, a nonsteroidal “device ”cream. This article reviews the practical topical management of seborrheic dermatitis in the United States, focusing on the adult population. PMID:21607192

  14. Electroporation of adult zebrafish.

    PubMed

    Rao, N Madhusudhana; Rambabu, K Murali; Rao, S Harinarayana

    2008-01-01

    We generated transient transgenic zebrafish by applying electrical pulses subsequent to injection of DNA into muscle tissue of 3-6-month old adult zebrafish. Electroporation parameters, such as number of pulses, voltage, and amount of plasmid DNA, were optimized and found that 6 pulses of 40 V/cm at 15 mug/fish increased the luciferase expression by 10-fold compared with those in controls. By measuring the expression of luciferase, in vivo by electroporation in adult zebrafish and in vitro using fish cell line (Xiphophorus xiphidium A2 cells), the strength of three promoters (CMV, human EF-1alpha, and Xenopus EF-1alpha) was compared. Subsequent to electroporation after injecting DNA in the mid region of zebrafish, expression of green fluorescent protein was found far away from the site of injection in the head and the tail sections. Thus, electroporation in adult zebrafish provides a rapid way of testing the behavior of gene sequences in the whole organism.

  15. Back pain in adults.

    PubMed

    Becker, Jonathan A; Stumbo, Jessica R

    2013-06-01

    This article provides a summary of the many causes of back pain in adults. There is an overview of the history and physical examination with attention paid to red flags that alert the clinician to more worrisome causes of low back pain. An extensive differential diagnosis for back pain in adults is provided along with key historical and physical examination findings. The various therapeutic options are summarized with an emphasis on evidence-based findings. These reviewed treatments include medication, physical therapy, topical treatments, injections, and complementary and alternative medicine. The indications for surgery and specialty referral are also discussed.

  16. [Adult oligosymptomatic coeliac disease].

    PubMed

    Cabral Rodríguez, R; Arrieta Blanco, F J; Vicente Sánchez, F; Cordobés Martín, F J; Moreno Caballero, B

    2004-12-01

    Coeliac disease is a chronic pathology of the small intestine. The pathogenic mechanism is caused by gluten intolerance. This disease present a characteristic and unspecific injury that causes nutrients and vitamins malabsorption. In adults is an underdiagnosed entity due to atypical forms. To make a premature diagnosis is basic because gluten-free diet prevent the complications after long-term like the intestinal T lymphoma and other digestives malignancies, and decrease the mortality of these patients. We present a case of adult oligosymptomatic coeliac disease in a patient with iron deficiency anaemia and vaginal bleeding. We study the clinic-nutrition and the alterations evolution of the patient.

  17. Adult Learning Matters

    ERIC Educational Resources Information Center

    Adults Learning, 2009

    2009-01-01

    The Campaigning Alliance for Lifelong Learning is to lobby parliament for the restoration of the 1.5 million adult learning places lost over the past two years. The campaign has attracted supporters from an astonishingly wide range of backgrounds. In this article, Gordon Marsden, Caroline Biggins, Beth Walker, Mike Chaney, Peter Davies, Sian…

  18. Facilitation of Adult Development

    ERIC Educational Resources Information Center

    Boydell, Tom

    2016-01-01

    Taking an autobiographical approach, I tell the story of my experiences facilitating adult development, in a polytechnic and as a management consultant. I relate these to a developmental framework of Modes of Being and Learning that I created and elaborated with colleagues. I connect this picture with a number of related models, theories,…

  19. Hearing Loss in Adults.

    ERIC Educational Resources Information Center

    House, John W.

    1997-01-01

    This article discusses hearing loss in adults. It begins with an explanation of the anatomy of the ear and then explains the three types of hearing loss: conductive hearing loss, sensorineural hearing loss, and mixed conductive-sensorineural hearing loss. Tinnitus, hearing aids, and cochlear implants are also addressed. (CR)

  20. Older Adult Education.

    ERIC Educational Resources Information Center

    Forman, Jeffrey

    In an effort to improve the quality of life for area senior citizens, De Anza College has established an older adult education program which combines adaptive physical education with holistic health care principles to instruct students in relaxation, nutrition, and physical activity. Classes are held in convalescent hospitals, retirement homes,…

  1. Adult Education in Brazil.

    ERIC Educational Resources Information Center

    Ministerio da Educacao e Cultura, Rio de Janeiro (Brazil).

    The status and goals of adult education programs in Brazil are discussed in this report. Supplemental systems such as the Brazilian Literacy Movement (Mobral) and their results are described and evaluated. Charts detailing the evolution of literacy are shown and priorities in education are suggested. The progress of other educational entities is…

  2. Adult Basic Education Curriculum.

    ERIC Educational Resources Information Center

    Massachusetts Career Development Inst., Springfield.

    This booklet, aimed at adult basic education students, pinpoints and summarizes a few common spelling rules to help make spelling easier, and includes a component on using the dictionary. In the text, each rule is presented with many examples. Exercises follow each spelling rule, allowing students the opportunity to apply the rule to specific…

  3. Police and Adult Education.

    ERIC Educational Resources Information Center

    Sims, Vic

    The literature on adult education for police is reviewed and criticized. Among the publications that have been influential in debating the need for police education are Charles B. Saunder's "The Challenge of Crime in a Free Society" (1976), which endorses the Presidential Commission on Law Enforcement's recommendations regarding the vital…

  4. Dance for Older Adults.

    ERIC Educational Resources Information Center

    Pruett, Diane Milhan, Ed.; And Others

    1983-01-01

    Dance programs for older adults that encourage exercise and socializing are described in six articles. Program guidelines of the American Alliance Committee on Aging are explained, and other articles emphasize a movement education approach that may involve intergenerational contact. A dance program held in a worship setting is also discussed. (PP)

  5. Migration and Adult Education

    ERIC Educational Resources Information Center

    Gois, William

    2007-01-01

    The objective of this paper is to highlight the role of adult education as a tool in addressing labour migration issues, specifically those concerning the protection of migrant workers' rights and the transformation of the impact of migration into positive holistic developmental gains. The view of labour migration as a means to forge the economic…

  6. How Do Adults Learn?

    ERIC Educational Resources Information Center

    Rogers, Alan; Illeris, Knud

    2003-01-01

    This dialog between Alan Rogers and Knud Illeris debates arguments Rogers made in a previous article about the differences between adult and child learning. Rogers emphasizes differences in teacher-learner relationships. Illeris believes the differences result from different motivations for learning. (SK)

  7. Encyclopedia of Adult Development.

    ERIC Educational Resources Information Center

    Kastenbaum, Robert, Ed.

    This encyclopedia contains 106 articles on adult development that were written by more than 75 specialists in such diverse fields as anthropology, communication, education, health sciences, history, and psychology. In a guide to related topics that is presented at the beginning of the encyclopedia, the 106 articles are grouped under the following…

  8. Sinusitis in adults - aftercare

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000563.htm Sinusitis in adults - aftercare To use the sharing features on this page, please enable JavaScript. Your sinuses are chambers in ... They are filled with air. Sinusitis is an infection of these chambers, which causes ...

  9. Helping Adults to Spell.

    ERIC Educational Resources Information Center

    Moorhouse, Catherine

    This book presents a range of strategies for adult literacy tutors and offers a wealth of practical advice on teaching spelling within the context of writing. Chapters 1-3 offer basic information on talking with the student about spelling, finding out how the student spells and helping the student to see himself/herself as a "good" speller, and…

  10. Immigration and Adult Transitions

    ERIC Educational Resources Information Center

    Rumbaut, Ruben G.; Komaie, Golnaz

    2010-01-01

    Almost 30 percent of the more than 68 million young adults aged eighteen to thirty-four in the United States today are either foreign born or of foreign parentage. As these newcomers make their transitions to adulthood, say Ruben Rumbaut and Golnaz Komaie, they differ significantly not only from one another but also from their native-parentage…

  11. Profiles of Adult Learners.

    ERIC Educational Resources Information Center

    Illinois State Library, Springfield.

    Since January 1986, when the Illinois Secretary of State Literacy Grant Program began funding a wide variety of adult literacy programs, more than 30,000 students have sought help with reading. They have been matched with 25,000 tutors who have provided more than 2 million hours of volunteer instruction. The profiles in this booklet are stories of…

  12. Adult Literacy Perspectives.

    ERIC Educational Resources Information Center

    Taylor, Maurice C., Ed.; Draper, James A., Ed.

    This book, intended to serve as a professional reference work, proposes to define the field of Adult Basic Education in its evolution, its contribution to professional education, and the principal problems and issues. The volume contains the following treatises: "Definitions and Evolution of the Concepts" (Thomas); "Selected…

  13. Depression - older adults

    MedlinePlus

    ... slowly than in younger adults. To better manage depression at home: Exercise regularly, if the provider says it is OK. Surround yourself with caring, positive people and do fun activities. ... signs of depression, and know how to react if these occur. ...

  14. TRENDS IN ADULT READING.

    ERIC Educational Resources Information Center

    MILLER, JUSTIN H.

    TRENDS EVIDENT IN ADULT READING DURING THE 1960'S IN THE AREAS OF ADMINISTRATION, PROGRAMS, TEACHING, TECHNIQUES, RESEARCH PROJECTS, AND METHODS OF PROMOTION OF READING PROGRAMS ARE DISCUSSED. TWO INSTANCES OF COMMERCIAL EXPLOITATION BASED ON INTENSE AND OFTEN FALLACIOUS ADVERTISING AND ON PUBLIC IGNORANCE ARE CITED. A POSITIVE TREND IN THE AREA…

  15. Newly Diagnosed: Older Adults

    MedlinePlus

    ... Children Newly Diagnosed: Older Adults Related Topics on AIDS.gov Aging with HIV/AIDS National HIV/AIDS ... an Emerging Challenge Last revised: 07/10/2015 AIDS.gov HIV/AIDS Basics • Federal Resources • Using New ...

  16. Utah Adult Education Services. Adult Education Report 1968-69.

    ERIC Educational Resources Information Center

    Utah State Board of Education, Salt Lake City.

    Major purposes for the preparation of this report on public school adult education in Utah were: to provide the public with a description of achievements, trends, and needs, and with meaningful cost accounting information; to make comparisons and analyses of adult education by program, school district, and year; and to provide the adult education…

  17. What is Young Adult Literature? (Young Adult Literature).

    ERIC Educational Resources Information Center

    Crowe, Chris, Ed.

    1998-01-01

    Outlines some of the many confusions about young adult literature. Sheds some light on what young adult literature is (defining it as all genres of literature published since 1967 that are written for and marketed to young adults). Discusses briefly how it can be used in schools. Offers a list of the author's 20 favorite books for teenagers. (SR)

  18. Teaching Nontraditional Adult Students: Adult Learning Theories in Practice

    ERIC Educational Resources Information Center

    Chen, Joseph C.

    2014-01-01

    As the USA experiences rapid growth of nontraditional adult students in higher education, educators and institutions will increasingly need to look beyond the traditional youth-centric educational models to better address adult learning needs. To date, no research has been conducted examining the learning experiences of adult students enrolled in…

  19. Congenital Heart Disease in Adults

    MedlinePlus

    ... and genetics may play a role. Why congenital heart disease resurfaces in adulthood Some adults may find that ... in following adults with congenital heart disease. Congenital heart disease and pregnancy Women with congenital heart disease who ...

  20. Adult Education for Social Mobilization.

    ERIC Educational Resources Information Center

    Echeverria, Luis

    1981-01-01

    Suggests some ideas that could stimulate and be incentives for defining programs of adult education in the future. These involve changing priorities, developing a framework which allows adult education programs to be established, and managing decision-making processes. (CT)

  1. College-Age & Young Adults

    MedlinePlus

    ... Adolescent Brain Comorbidity College-Age & Young Adults Criminal Justice Drugged Driving Drug Testing Drugs and the Brain ... Age & Young Adults College Addiction Studies Programs Criminal Justice Drugged Driving Drug Testing Drugs and the Brain ...

  2. Renal Disease and Adult Vaccination

    MedlinePlus

    ... Resources for Healthcare Professionals Renal Disease and Adult Vaccination Recommend on Facebook Tweet Share Compartir Vaccines are ... have immunity to this disease Learn about adult vaccination and other health conditions Asplenia Diabetes Type 1 ...

  3. Alcohol Use and Older Adults

    MedlinePlus

    ... version of this page please turn Javascript on. Alcohol Use and Older Adults Alcohol and Aging Adults of any age can have ... Escape (Esc) button on your keyboard.) What Is Alcohol? Alcohol, also known as ethanol, is a chemical ...

  4. Liver Disease and Adult Vaccination

    MedlinePlus

    ... Vaccination Recommendations Adult Vaccination Resources for Healthcare Professionals Liver Disease and Adult Vaccination Recommend on Facebook Tweet ... critical for people with health conditions such as liver disease. If you have chronic liver disease, talk ...

  5. Enhancing Older Adults' Reading Comprehension.

    ERIC Educational Resources Information Center

    Kemper, Susan; And Others

    1993-01-01

    Investigates older adults' reading comprehension skills through syntactic measures and measures of sentence content. Analyzes the apparent reading difficulties of older adults. Provides guidelines for the preparation of prose materials for older readers. (HB)

  6. Adult Development and the Workplace.

    ERIC Educational Resources Information Center

    Heffernan, James M.

    Little attention has been given to how adults develop through their lifetimes and what roles their workplace environments play in that development. Research and theory regarding adult psychosocial development have confirmed the developmental life-cycle phases of adulthood. These are: leaving the family (ages 16-22), getting into the adult world…

  7. Facilitating Creativity in Adult Learners

    ERIC Educational Resources Information Center

    Tsai, Kuan Chen

    2013-01-01

    Creativity in education research has received increasing attention, although the major focus of this research has been on children. Despite pleas by several adult educators for promoting creativity, very few studies have focused on adult learners, leaving to it to be explored what approaches are useful for adult educators to facilitate creativity…

  8. Adult Learning. ARIS Information Sheet.

    ERIC Educational Resources Information Center

    National Languages and Literacy Inst. of Australia, Melbourne. Adult Education Resource and Information Service.

    This information sheet provides a summary of general observations regarding adult learners. Adults from different walks of life may seek out learning at different times in their lives, for different reasons, and for vastly different purposes. Adult learning groups may include students of different ages, cultures, and educational and socioeconomic…

  9. Assessment Tools for Adult Education.

    ERIC Educational Resources Information Center

    Shefrin, Carol; Shafer, Dehra; Forlizzi, Lori

    The Assessment Tools for Adult Education project was designed to provide training and support to staff of the Pennsylvania Bureau of Adult Basic and Literacy Education (ABLE) funded programs to help them use assessment tools and procedures to document the learning gains of the adult students they serve. The following candidate assessment…

  10. The Politics of Adult Education

    ERIC Educational Resources Information Center

    Adam, Roy

    1974-01-01

    All educational levels have been attacked by politicians and haunted by suspicion, and adult education has drawn more than its share. Interest groups have had a large effect on adult education. The construction of a theoretical model of the politics of adult education is suggested. (DS)

  11. Adult Multiple Intelligences and Math.

    ERIC Educational Resources Information Center

    Costanzo, Meg Ryback

    In the Adult Multiple Intelligences (AMI) study, 10 teachers of adults from the northeastern region of the United States explored for 18 months the ways that multiple intelligences (MI) theory could support instruction and assessment in various adult learning contexts. The results of this research were published in a book by Julie Viens called MI…

  12. New Thrusts in Adult Education.

    ERIC Educational Resources Information Center

    Worthington, Robert M.

    The Associate Commissioner of the Bureau of Adult, Vocational, and Technical Education is responsible for two broad and important programs, career education and broader and better services in adult education. Career education is a lifelong educational process beginning in kindergarten and extending through adult and continuing education. Career…

  13. Adult Education and Development, 1994.

    ERIC Educational Resources Information Center

    Adult Education and Development, 1994

    1994-01-01

    The publication is a half-yearly journal for adult education in Africa, Asia, and Latin America. Issue 42 includes the following: "Adult Education for Self-Reliance in Community Health Education Programmes" (Kweka); "Promoting Good Nutrition" (Mangvwat); "Incorporating Health-Improvement Activities in Adult Education…

  14. Adult Learning and HRD. Symposium.

    ERIC Educational Resources Information Center

    2002

    This symposium on adult learning and human resource development consists of three presentations. "Adult Learning Principles and Concepts in the Workplace: Implications for Training in HRD" (Margot B. Weinstein) reports on findings from interviews with restaurant employees who reported that training practices using adult learning…

  15. Adult Education through World Collaboration.

    ERIC Educational Resources Information Center

    Cassara, Beverly Benner, Ed.

    This book contains the following papers about development/delivery of adult education through the efforts of multinational and bilateral government donors and the International Council for Adult Education (ICAE): "Preface" (Beverly Benner Cassara); "Introduction: Adult Education and Democracy" (Francisco Vio Grossi);…

  16. Diarrhoea in adults (acute)

    PubMed Central

    2011-01-01

    Introduction An estimated 4.6 billion cases of diarrhoea occurred worldwide in 2004, resulting in 2.2 million deaths. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for acute diarrhoea in adults living in resource-rich countries? What are the effects of treatments for acute mild-to-moderate diarrhoea in adults from resource-rich countries travelling to resource-poor countries? What are the effects of treatments for acute mild-to-moderate diarrhoea in adults living in resource-poor countries? What are the effects of treatments for acute severe diarrhoea in adults living in resource-poor countries? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 72 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: antibiotics, antimotility agents, antisecretory agents, bismuth subsalicylate, diet, intravenous rehydration, nasogastric tube rehydration, oral rehydration solutions (amino acid oral rehydration solution, bicarbonate oral rehydration solution, reduced osmolarity oral rehydration solution, rice-based oral rehydration solution, standard oral rehydration solution), vitamin A supplementation, and zinc supplementation. PMID:21718555

  17. CDC Vital Signs: Adults with Disabilities

    MedlinePlus

    ... Problem More adults with disabilities need to get physical activity. Adults with disabilities who get no physical activity ... Adults with disabilities are more likely to get physical activity if doctors recommend it. Only 44% of adults ...

  18. An Undergraduate Course in Adult Development: When the Virtual Adult Is an Adult

    ERIC Educational Resources Information Center

    Williams, Robert B.

    2014-01-01

    An aspect of an undergraduate psychology course on adult development was the preparation of case records on adults who consented to be studied. Participants (1) developed their abilities to observe and accurately record adult behavior across a variety of ages and contexts; (2) withheld judgments about behavior when evidence was lacking; (3)…

  19. The adult scoliosis.

    PubMed

    Aebi, Max

    2005-12-01

    Adult scoliosis is defined as a spinal deformity in a skeletally mature patient with a Cobb angle of more than 10 degrees in the coronal plain. Adult scoliosis can be separated into four major groups: Type 1: Primary degenerative scoliosis, mostly on the basis of a disc and/or facet joint arthritis, affecting those structures asymmetrically with predominantly back pain symptoms, often accompanied either by signs of spinal stenosis (central as well as lateral stenosis) or without. These curves are often classified as "de novo" scoliosis. Type 2: Idiopathic adolescent scoliosis of the thoracic and/or lumbar spine which progresses in adult life and is usually combined with secondary degeneration and/or imbalance. Some patients had either no surgical treatment or a surgical correction and fusion in adolescence in either the thoracic or thoracolumbar spine. Those patients may develop secondary degeneration and progression of the adjacent curve; in this case those curves belong to the type 3a. Type 3: Secondary adult curves: (a) In the context of an oblique pelvis, for instance, due to a leg length discrepancy or hip pathology or as a secondary curve in idiopathic, neuromuscular and congenital scoliosis, or asymmetrical anomalies at the lumbosacral junction; (b) In the context of a metabolic bone disease (mostly osteoporosis) combined with asymmetric arthritic disease and/or vertebral fractures. Sometimes it is difficult to decide, what exactly the primary cause of the curve was, once it has significantly progressed. However, once an asymmetric load or degeneration occurs, the pathomorphology and pathomechanism in adult scoliosis predominantly located in the lumbar or thoracolumbar spine is quite predictable. Asymmetric degeneration leads to increased asymmetric load and therefore to a progression of the degeneration and deformity, as either scoliosis and/or kyphosis. The progression of a curve is further supported by osteoporosis, particularly in post-menopausal female

  20. Adult respiratory distress syndrome.

    PubMed

    Cutts, S; Talboys, R; Paspula, C; Prempeh, E M; Fanous, R; Ail, D

    2017-01-01

    Adult respiratory distress syndrome (ARDS) has now been described as a sequela to such diverse conditions as burns, amniotic fluid embolism, acute pancreatitis, trauma, sepsis and damage as a result of elective surgery in general. Patients with ARDS require immediate intubation, with the average patient now being ventilated for between 8 and 11 days. While the acute management of ARDS is conducted by the critical care team, almost any surgical patient can be affected by the condition and we believe that it is important that a broader spectrum of hospital doctors gain an understanding of the nature of the pathology and its current treatment.