AUTHOR=Arp Alex P. , Hunter Wayne B. , Pelz-Stelinski Kirsten S. 

TITLE=Annotation of the Asian Citrus Psyllid Genome Reveals a Reduced Innate Immune System

JOURNAL=Frontiers in Physiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2016.00570

DOI=10.3389/fphys.2016.00570

ISSN=1664-042X

ABSTRACT=<p>Citrus production worldwide is currently facing significant losses due to citrus greening disease, also known as Huanglongbing. The citrus greening bacteria, <italic>Candidatus</italic> Liberibacter asiaticus (<italic>C</italic>Las), is a persistent propagative pathogen transmitted by the Asian citrus psyllid, <italic>Diaphorina citri</italic> 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 <italic>D. citri</italic> draft genome was used to characterize the immune defense genes present in <italic>D. citri</italic>. Predicted mRNAs identified by screening the published <italic>D. citri</italic> 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 <italic>D. citri</italic>. In contrast, <italic>D. citri</italic> 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 <italic>D. citri</italic> has a reduced immune capability similar to that observed in <italic>A. pisum, P. humanus</italic>, and <italic>R. prolixus</italic>. The absence of immune system genes from the <italic>D. citri</italic> genome may facilitate <italic>C</italic>Las infections, and is possibly compensated for by their relationship with their microbial endosymbionts.</p>