Carica papaya MicroRNAs Are Responsive to Papaya meleira virus Infection

Abstract

MicroRNAs are implicated in the response to biotic stresses. Papaya meleira virus (PMeV) is the causal agent of sticky disease, a commercially important pathology in papaya for which there are currently no resistant varieties. PMeV has a number of unusual features, such as residence in the laticifers of infected plants, and the response of the papaya to PMeV infection is not well understood. The protein levels of 20S proteasome subunits increase during PMeV infection, suggesting that proteolysis could be an important aspect of the plant defense response mechanism. To date, 10,598 plant microRNAs have been identified in the Plant miRNAs Database, but only two, miR162 and miR403, are from papaya. In this study, known plant microRNA sequences were used to search for potential microRNAs in the papaya genome. A total of 462 microRNAs, representing 72 microRNA families, were identified. The expression of 11 microRNAs, whose targets are involved in 20S and 26S proteasomal degradation and in other stress response pathways, was compared by real-time PCR in healthy and infected papaya leaf tissue. We found that the expression of miRNAs involved in proteasomal degradation increased in response to very low levels of PMeV titre and decreased as the viral titre increased. In contrast, miRNAs implicated in the plant response to biotic stress decreased their expression at very low level of PMeV and increased at high PMeV levels. Corroborating with this results, analysed target genes for this miRNAs had their expression modulated in a dependent manner. This study represents a comprehensive identification of conserved miRNAs inpapaya. The data presented here might help to complement the available molecular and genomic tools for the study of papaya. The differential expression of some miRNAs and identifying their target genes will be helpful for understanding the regulation and interaction of PMeV and papaya.

Label-free quantitative proteomic analysis of pre-flowering PMeV-infected Carica papaya L.

“…MicroRNA coding genes predicted to target proteasome-related proteins, for instance ubiquitin-3-ligases, also accumulated in C. papaya sticky-diseased leaves suggesting their involvement in the control of protein turnover [7]. However, limited knowledge about key players of the PMeV x C. papaya interaction mechanism impairs the development of virus resistant plant genotype(s) and a differential proteomic study investigating the effects of infection at the protein level could be of value to this effort.…”

A Current Overview of the Papaya meleira virus, an Unusual Plant Virus

“…However, the conservation of mature miRNAs between plant species has enabled a computer-based approach to predict the secondary structures of the sequences surrounding miRNA. Actually, 4,251 plant mature miRNA sequences from the Plant miRNAs Database were used to search for hairpin structures in the C. papaya genome [ 60 ]. 462 known miRNA sequences were detected in 537 hairpins in the C. papaya genome; additionally, these miRNAs were classified into 72 miRNAs families [ 60 ].…”

“…Changes in miRNA expression are associated with viral infection in Arabidopsis [ 61 ], and viral protein-induced alterations in miRNA expression have been associated with symptom development in Nicotiana tabacum [ 62 ]. Therefore, in order to understand the unique plant-virus interaction between PMeV and C. papaya , and, consequently, the mechanisms involved in the onset of sticky disease symptoms, the miRNA response of the plant to infection was investigated [ 60 ]. The MicroRNAs that target the components of the 20S and 26S proteasomal degradation processes and components of other stress response pathways were studied.…”

Suppression of nbe‐miR166h‐p5 attenuates leaf yellowing symptoms of potato virus X on Nicotiana benthamiana and reduces virus accumulation

“…Viruses are economically important plant pathogens that typically cause symptoms of yellowing, mosaic, twisting and even necrosis of leaves, and plant death in many cases. Studies with many different viruses have shown that virus‐infected plants generally have a changed expression profile of miRNAs (Abreu et al ., ; Amin et al ., ; Bazzini et al ., ; Chen et al ., , ; Cillo et al ., ; Du et al ., ; Feng et al ., , ; Guo et al ., ; Lang et al ., , ; Liu et al ., ; Naqvi et al ., ; Pradhan et al ., ; Sun et al ., ; Wang et al ., ; Xu et al ., ; Yang et al ., ) and, in some cases, these changes are associated with viral symptoms (Gao et al ., ; Lian et al ., ; Romanel et al ., ). Bazzini et al.…”