Citrus tristeza virus P33 Protein Is Required for Efficient Transmission by the Aphid Aphis (Toxoptera) citricidus (Kirkaldy)

Abstract

Plant viruses are threatening many valuable crops, and Citrus tristeza virus (CTV) is considered one of the most economically important plant viruses. CTV has destroyed millions of citrus trees in many regions of the world. Consequently, understanding of the transmission mechanism of CTV by its main vector, the brown citrus aphid, Aphis (Toxoptera) citricidus (Kirkaldy), may lead to better control strategies for CTV. The objective of this study was to understand the CTV–vector relationship by exploring the influence of viral genetic diversity on virus transmission. We built several infectious clones with different 5′-proximal ends from different CTV strains and assessed their transmission by the brown citrus aphid. Replacement of the 5′- end of the T36 isolate with that of the T30 strain (poorly transmitted) did not increase the transmission rate of T36, whereas replacement with that of the T68-1 isolate (highly transmitted) increased the transmission rate of T36 from 1.5 to 23%. Finally, substitution of p33 gene of the T36 strain with that of T68 increased the transmission rate from 1.5% to 17.8%. Although the underlying mechanisms that regulate the CTV transmission process by aphids have been explored in many ways, the roles of specific viral proteins are still not explicit. Our findings will improve our understanding of the transmission mechanisms of CTV by its aphid vector and may lead to the development of control strategies that interfere with its transmission by vector.

Mining Public Data to Investigate the Virome of Neglected Pollinators and Other Floral Visitors

“…Therefore, further studies are needed to fully characterize the sixteen transcripts described here in order to know whether the viral transcripts infect plants with economic value. It is important to highlight that the only virus previously described in A. aurantii was the Citrus Tristeza Virus [ 16 ]. Therefore, it is critical to assess the potential pathogenicity of these viruses to pollinators and in order to develop appropriate management and mitigation strategies for both plant and insect populations, also taking into account the viral infection in different insect developmental stages.…”

“…For instance, Aphis aurantii , commonly known as the orange aphid, is a sap-sucking insect that feeds on various plant species, including citrus trees. Despite being recognized as a potential vector for transmitting plant viruses, studies elucidating its associated microbiome and virome remain scarce or restricted to the transmission of Citrus tristeza virus [ 16 ]. Similarly, other flower-visiting insects like Dasyhelea sp., Atrichopogon sp., Forcipomyia taiwana , and Trigona ventralis hoozana , representing distinct groups, have received little attention regarding their microbial and viral communities.…”

Current Status of Citrus Tristeza Virus in Major Citrus Growing Areas of Sargodha, Pakistan

“…In various countries, the negative impacts of CTV disease were countered by incorporating a cross-protection technique. Plants were inoculated with mild-strain of CTV to reduce the devastating effects of subsequent infections that can be introduced by aphids (Shilts et al, 2020).…”

Nucleotide Sequence Assessment of Four ORFs of Citrus Tristeza Virus: Evidence of Recombination

“…Certain deletion combinations of these three genes have been shown to improve stem pitting symptoms, while others were shown to reduce stem pitting symptoms [5]. p33 protein is necessary for effective transmission by the aphid vector (Toxoptera citricida) [6], three suppressors of RNA silencing (p25, p20, and p23) [7,8]. The p23 protein is an RNA binding protein and thought to play a regulatory role in the expression of other CTV genes and could be used as a disease severity indicator [9].…”