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

ABSTRACT: 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 Ca(2+), Mg(2+) or Zn(2+), however, Zn(2+) (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.

SUBMITTER: Van Ekert E

PROVIDER: S-EPMC4398755 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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

Van Ekert Evelien E Shatters Robert G RG Rougé Pierre P Powell Charles A CA Smagghe Guy G Borovsky Dov D

FEBS open bio 20150328

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 adul ...[more]

PMID: 25893162

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Project description:BackgroundCitrus huanglongbing (HLB) is a destructive disease of citrus and a major threat to the citrus industry around the world. This disease accounts for substantial economic losses in China every year. Diaphorina citri Kuwayama is one of the major vectors by which citrus HLB is spread under natural conditions in China. Research is needed to identify the geographic distribution of D. citri and its major areas of occurrence and to formulate measures for early warning, monitoring, and control of this pest and citrus HLB.MethodsIn this study, the ecological niche modelling software MaxEnt (maximum entropy model) was combined with ArcGIS (a geographic information system) to predict the potential geographic distribution of D. citri in China. Key environmental factors and the appropriate ranges of their values were also investigated.ResultsOur results show that the training data provided a good forecast (AUCmean = 0.988). The highly suitable areas for D. citri in China are mainly concentrated to the south of the Yangtze River, and the total area is 139.83 × 104 km2. The area of the moderately suitable areas is 27.71 × 104 km2, with a narrower distribution than that of the highly suitable area. The important environmental factors affecting the distribution of D. citri were min temperature of coldest month, mean temperature of coldest quarter, precipitation of wettest quarter, mean temperature of warmest quarter, precipitation of warmest quarter, max temperature of warmest month, and temperature seasonality. These results provide a valuable theoretical basis for risk assessments and control of D. citri.DiscussionThe predicted results showed that there were highly suitable areas for D. citri in Chongqing, Hubei, Anhui, and Jiangsu. Therefore, the possibility exists for the further spread of D. citri in China in the future. Extreme temperature variables, especially the min temperature of the coldest month, play an important role in the distribution of D. citri and are most closely related to the distribution of D. citri.

Project description: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 depending on individual or regional assessment of all factors.

Dataset Information

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

Publications

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

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