Analyses of mitogenome sequences revealed that Asian citrus psyllid (Diaphorina citri) from California was related to those from Florida but different from those in Southern China

Authors: WU, F - South China Agricultural University; KUMAGAI, L - California Department Of Food And Agriculture; CEN, Y - South China Agricultural University; Chen, Jianchi; Wallis, Christopher; Polek, Marylou; JIANG, H - South China Agricultural University; LIANG, G - South China Agricultural University; DENG, X - South China Agricultural University

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2017
Publication Date: 8/31/2017
Citation: Wu, F., Kumagai, L.B., Cen, Y., Chen, J., Wallis, C.M., Polek, M., Jiang, H., Liang, G., Deng, X. 2017. Analyses of mitogenome sequences revealed that Asian citrus psyllid (Diaphorina citri) from California was related to those from Florida but different from those in Southern China. Scientific Reports. 7:10154. https://doi.org/10.1038/s41598-017-10713-3.
DOI: https://doi.org/10.1038/s41598-017-10713-3

Interpretive Summary: Asian citrus psyllid (ACP) transmits the pathogen of citrus Huanglongbing (HLB, yellow shoot disease, also called citrus greening disease). HLB is currently threatening citrus production in all citrus growing regions, including California. To develop effective HLB control strategies, knowledge of ACP is necessary. In this study, mitochondrial genome (mitogenome) sequences of ACP from California and Florida were acquired and compared with those from China in an attempt to infer relationships between Californian, Floridian, and Chinese ACP. Based on mitogenome sequence analyses, the Californian ACP was found to be identical to the Floridian ACP, but different from the ACP in China. This suggests that ACP in California likely was introduced from southeastern USA, potentially through cross-continent transportation of citrus materials. This is the first report on the geographical origin of California ACP, and the information will have direct impact on HLB control practice in California.

Technical Abstract: Asian citrus psyllid (ACP, Diaphorina citri Kuwayama; Hemiptera: Liviidae) transmits “Candidatus Liberibacter asiaticus” (CLas), an unculturable alpha-proteobacterium associated with citrus Huanglongbing (HLB, yellow shoot disease, also called citrus greening disease). HLB is threatening citrus production in all citrus growing regions, including California. New knowledge of ACP population diversity is necessary for development of HLB management strategies. In this study, mitogenome sequences of ACP from California (mt-CApsy, 15,027 bp) and Florida (mt-FLpsy, 15,012 bp), USA, were acquired. As for the previously published mitogenome sequence (mt-GDpsy, 14,996 bp) from Guangdong, China, the ACP mitogenomes contained 13 protein coding genes (PCGs), 2 ribosomal RNA (rRNA), 22 transfer RNA (tRNA) genes, and a control region (CR). PCR flanking the CR generated multiple amplicons from single ACPs, indicating size variation of CR and therefore ACP mitogenome. This is the first report of mitogenome size variation in psyllids (Psylloidea), and the biological role remains unclear. The Californian mt-CApsy was identical to the Florida mt-FLpsy, but different from the Guangdong mt-GDpsy in 39 single nucleotide polymorphisms (SNPs). Further analyses were performed on cox1 and trnAsn regions with 100 ACP individuals (20 from California, 20 from Florida, and 60 from China). All results showed the presence of a Chinese ACP cluster (CAC) and an American ACP cluster (AAC). Two primer sets based on SNPs in nad1-nad4-nad5 were designed and effectively differentiated CAC from AAC by conventional PCR. Based on these mitogenome analyses, it was concluded likely that ACP in California was introduced from southeastern USA.