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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Molecular Plant Pathology Laboratory » Research » Publications at this Location » Publication #331009
Title: Transcriptome analysis of citrus sinensis in response to dual infection by Citrius tristeza virus and ’Candidatus liberibacter asiaticus'

Author
item FU, SHIMIN - Southwest University
item Shao, Jonathan
item Paul, Cristina
item Hartung, John

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2015
Publication Date: 3/10/2015
Citation: Fu, S., Shao, J.Y., Paul, C., Hartung, J.S. 2015. Transcriptome analysis of citrus sinensis in response to dual infection by Citrius tristeza virus and ’Candidatus liberibacter asiaticus'. Phytopathology. 105:1013-1025. http://dx.doi.org/10.1094/PHYTO-03-15-0064-R.

Interpretive Summary:

Technical Abstract: Huanglongbing (HLB) and Tristeza are destructive and globally distributed citrus diseases, and are responsible for the tremendous economic losses to the citrus industries worldwide. HLB is caused by a gram-negative and phloem-limited member of the a-Proteobacteria, Candidatus Liberibacter asiaticus. CaLas can be transmitted through grafting and by the citrus psyllid, Diaphorina citri. Tristeza is caused by Citrus tristeza virus (CTV), a member of the Closteroviridae with a single-stranded and positive sense RNA-genome, and is transmitted by grafting and aphids, notably Toxoptera citricidus. CTV strains vary widely in symptoms, from very mild strains that do not cause damage to citrus hosts, to severe strains that induce symptoms that can resemble those induced by CaLas and may be lethal. These overlapping symptom patterns include leaf yellowing, leaf stiffening and cupping, which can be associated with alterations in sucrose metabolism in the phloem, decline of roots and collapse of phloem tissue. A previous transcriptome study of Citrus sinensis separately inoculated with CaLas-B232, mild CTV-B2 and severe CTV-B6 respectively was done. We found that the circadian rhythm system of C. sinensis and ion balances were perturbed by all three pathogens but to differing degrees. Defense responses related to cell wall modification, transcriptional regulation, hormones, secondary metabolites, kinases and stress were activated by all three pathogens but with different patterns. In the current study, transcriptome profiles of C. sinensis co-infected with CTV-B2/CaLas-B232 (B2/232) and CTV-B6/CaLas-B232 (B6/232) were collected. We found many primary metabolic pathways, such as carbohydrate, amino acid and lipid were deeply reconfigured in response to B2/232 and B6/232, to a much greater degree than in an infection by a single pathogen. Photosynthesis, glycolysis, pentose phosphate and tricarboxylic acid pathways were all strongly repressed by B2/232 and B6/232, especially by the latter combination. Zinc transporters ZIP1, ZIP4, ZIP5 and phloem proteins PP2-B15 showed very different expression patterns in response to dual pathogens infection and single pathogen infection. These results indicated that severe CTV-B6 may cooperate with CaLas-B232 by contributing to the weakening of the plant through root decline and phloem blockage, and that defense responses activated by mild CTV-B2 may provide some beneficial effect on CaLas-B232.