Transcriptome analyses of Bactericera cockerelli adults in response to “Candidatus Liberibacter solanacearum” infection
- 1.4k Downloads
The potato/tomato psyllid, Bactericera cockerelli (Šulc) is an economically important crop pest that not only causes damage through its feeding but also transmits the bacterium, “Candidatus Liberibacter solanacearum” (CLs), which causes zebra chip disease in potato. There is some information about the phenotypic effects of phytopathogenic bacteria on their insect vectors; however, there are no published reports of the molecular mechanisms underlying phytopathogenic bacteria–insect vector interaction. In order to investigate the effects of CLs infection on B. cockerelli, transcriptomic analyses of CLs-infected and uninfected adult psyllids that were reared on potato were performed. De novo assembly of cDNA sequences generated 136,518 and 109,983 contigs for infected and uninfected insect libraries with an average contig length of 514 bp. BlastX analysis against the NCBI-nr database revealed that 33.33 % had significant matches. Gene ontology data illustrated that the majority of the expressed psyllid genes are involved in metabolic process, biological regulation, binding and catalytic activity. The psyllid transcriptome had an abundance of genes such as vitellogenin, heat shock protein, ejaculatory bulb-specific protein, ferritin, and cytochrome oxidase. Notably absent in the psyllid transcriptome were innate immunity genes induced in response to Gram-negative bacteria (IMD pathway). Several functionally diverse contigs related to symbiotic bacteria including the primary endosymbiont Carsonella ruddii, Wolbachia, and CLs in the psyllid transcriptome were identified. A total of 247 contigs showed differential expression in response to CLs infection including immune and stress-related genes and vitellogenins. Expression analyses of selected psyllid genes were performed on psyllids that were exclusively reared on potato (host of the insects used for RNAseq) and psyllids exclusively reared on tomato (alternative host of psyllids). These genes showed similar expression patterns irrespective of the host plant on which the psyllids were reared, which suggests that host–plant association may not modulate expression of these genes. Our findings suggest that the impact of CLs on psyllid transcriptome was to a large extent on genes involved in metabolic processes and to a small extent on immune and stress response genes. This study is the first description of transcriptomic changes in an insect vector in response to infection with a naturally occurring bacterial plant pathogen. Data from this study provide new sequence and gene expression resources for functional genomics of potato psyllids.
KeywordsZebra chip Potato psyllid Liberibacter RNASeq
We thank Drs. Rush, Henne and Munyaneza for supplying psyllid stocks that were used to establish the colonies used in this study.
- Cranshaw WS (2001) Diseases caused by insect toxin: psyllid yellows. In: Stevenson WR, Loria R, Franc GD, Weingartner PD (eds) Compendium of potato diseases, 2nd edn. APS, St. Paul, pp 73–74Google Scholar
- Crosslin JM, Munyaneza JE, Brown JK, Liefting LW (2010) Potato zebra chip disease: a phytopathological tale. Plant Health Progr. doi: 10.1094/PHP-2010-0317-1001-RV
- Gerardo N, Altincicek B, Anselme C, Atamian H, Barribeau S, de Vos M, Duncan E, Evans J, Gabaldon T, Ghanim M, Heddi A, Kaloshian I, Latorre A, Moya A, Nakabachi A, Parker B, Perez-Brocal V, Pignatelli M, Rahbe Y, Ramsey J, Spragg C, Tamames J, Tamarit D, Tamborindeguy C, Vincent-Monegat C, Vilcinskas A (2010) Immunity and other defenses in pea aphids Acyrthosiphon pisum. Genome Biol 11(2):R21PubMedCrossRefGoogle Scholar
- Hunter WB, Dowd SE, Katsar CS, Shatters RGJ, McKenzie CL, Hall DG (2009) Psyllid biology: expressed genes in adult Asian citrus psyllids Diaphorina citri Kuwayama. Open Entomol J 3(18):18–29Google Scholar
- MAFBNZ (2008) http://www.biosecurity.govt.nz/pestdiseases/plants/potato-tomato-psyllid.htm (accessed 18 September 2008)
- Pack HJ (1930) Potato psyllid. Utah Agric Expt Stn Bull 216:21Google Scholar
- Pletsch DJ (1947) The potato psyllid Paratrioza cockerelli (Sulc), its biology and control. Montana Agric Exp Stn Bull 446:95Google Scholar
- Purcell AH (1982a) Evolution of the insect vector relationship. In: Mount MS, Lacey GH (eds) Phytopathogenic prokaryotes. Academic Press, New York, pp 121–156Google Scholar
- Secor GA, Rivera-Varas VV (2004) Emerging diseases of cultivated potato and their impact on Latin America. Revista Latinoamericana de la Papa (Suplemento) 1:1–8Google Scholar
- Wallis RL (1955) Ecological studies on the potato psyllid as a pest of potatoes, vol 1107. Tech Bull, US Dep Agric, pp 1–24Google Scholar