Title: Targeting juvenile hormone metabolic genes in the Asian citrus psyllid (Diaphorina citri Kuwayama) as a strategy to reduce the spread of citrus greening disease Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 17, 2012
Publication Date: December 26, 2012
Citation: Van Ekert, E., Borovsky, Powell, C.A., Cave, R.D., Alessandro, R.T., Shatters, R.G. 2012. Targeting juvenile hormone metabolic genes in the Asian citrus psyllid (Diaphorina citri Kuwayama) as a strategy to reduce the spread of citrus greening disease [abstract]. International Research Citrus Huanglongbing Conference, February 4-8, 2013, Orlando, Florida. Technical Abstract: Diaphorina citri Kuwayama, the Asian citrus psyllid (ACP), is a devastating citrus pest due to its transmission of a phloem-limited bacterial pathogen, Candidatus Liberibacter asiaticus, that causes citrus greening. Psyllid control is a major part of effective greening disease management, and our research targets perturbation of insect juvenile hormone (JH) metabolism as a new psyllid control strategy. Application of a JH analogue, pyriproxyfen, is known to produce ovicidal/nymphicidal effects, morphological abnormalities, and reduced fecundity in ACP adults. These observations prompted us to identify a JH biosynthetic enzyme as target for biologically-based control strategies, as an alternative to heavy reliance on broad-spectrum pesticides. First, a candidate gene/cDNA encoding the JH biosynthetic enzyme, JH acid methyl transferase (DcJHAMT) was identified through computational analysis of the D. citri genome. Second, JHAMT cDNA was cloned, expressed in E. coli and a functional protein was purified. The recombinant enzyme prefers farnesoic acid over JH acid as a substrate, making DcJHAMT the penultimate enzyme in the JH biosynthetic pathway. DcJHAMT has high affinity for substrates leading to both JH I and JH III synthesis, making it plausible that both juvenoids are present in the ACP. Results are discussed with respect to mechanisms of juvenile hormone biosynthesis in the ACP and targeting this process as an interdiction point for ACP control.