Preliminary Report on the Acquisition, Persistence, and Potential Transmission of Citrus tristeza virus by Diaphorina citri

Citrus tristeza virus (CTV) is one of the most important citrus tree viruses: a graft-transmissible virus that can be vectored by several aphid species. Diaphorina citri is the insect vector of “Candidatus Liberibacter spp.”, a bacterium associated with citrus Huanglongbing (HLB). However, no detailed description of the relationship between CTV and D. citri has been reported. In this study, D. citri adults collected from CTV-infected “Shatangju” mandarin, “Newhall” sweet orange, and “fingered citron” trees in different orchards yielded CTV-positive rates of 40%, 65%, and 95%, respectively, upon detection by conventional PCR. Illumina HiSeq sequencing followed by de novo assembly recovered the primary full CTV genome from the RNA of 30 D. citri adults sampled from CTV-positive citrus plants. Molting and adult emergence did not affect the presence or titers of CTV within the D. citri; however, the persistence of CTV in psyllids varied among different host plant species. Groups of 10 D. citri (from a population 85% CTV-positive) were shown to potentially transmit CTV to two citrus species, “Shatangju” mandarin and “Eureka” lemon, yielding 58.33% and 83.33% CTV-positive plants, respectively. No transmission of CTV to orange jasmine plants occurred. Thus, this study reports on the ability of D. citri to acquire and transmit CTV, making D. citri as a vector of two important citrus pathogens, warranting further attention and investigation.