Citrus psorosis virus 24K protein interacts with citrus miRNA precursors, affects their processing and subsequent miRNA accumulation and target expression

Abstract

Sweet orange (Citrus sinensis), one of the most important fruit crops worldwide, may suffer from disease symptoms induced by virus infections, thus resulting in dramatic economic losses. Here, we show that the infection of sweet orange plants with two isolates of Citrus psorosis virus (CPsV) expressing different symptomatology alters the accumulation of a set of endogenous microRNAs (miRNAs). Within these miRNAs, miR156, miR167 and miR171 were the most down-regulated, with almost a three-fold reduction in infected samples. This down-regulation led to a concomitant up-regulation of some of their targets, such as Squamosa promoter-binding protein-like 9 and 13, as well as Scarecrow-like 6. The processing of miRNA precursors, pre-miR156 and pre-miR171, in sweet orange seems to be affected by the virus. For instance, virus infection increases the level of unprocessed precursors, which is accompanied by a concomitant decrease in mature species accumulation. miR156a primary transcript accumulation remained unaltered, thus strongly suggesting a processing deregulation for this transcript. The co-immunoprecipitation of viral 24K protein with pre-miR156a or pre-miR171a suggests that the alteration in the processing of these precursors might be caused by a direct or indirect interaction with this particular viral protein. This result is also consistent with the nuclear localization of both miRNA precursors and the CPsV 24K protein. This study contributes to the understanding of the manner in which a virus can alter host regulatory mechanisms, particularly miRNA biogenesis and target expression.

RNA-binding protein immunoprecipitation as a tool to investigate plant miRNA processing interference by regulatory proteins of diverse origin

“…Post-transcriptional alterations may include miRNA processing, accumulation and activity. Recent studies revealed that some viral proteins (VP) interfere with pre-miRNA nuclear export and processing by DICER, as is the case of adenovirus [ 15 ] and the Ophiovirus Citrus psorosis virus (CPsV) [ 16 ]. CPsV 24K protein interacts with pre-miR156 a and pre-miR171 a in Nicotiana benthamiana plants, causing a higher accumulation of unprocessed precursor species and a concomitant downregulation of mature miRNA species.…”

“…CPsV 24K protein interacts with pre-miR156 a and pre-miR171 a in Nicotiana benthamiana plants, causing a higher accumulation of unprocessed precursor species and a concomitant downregulation of mature miRNA species. Consequently, target transcript accumulation is upregulated, possibly leading to differential symptom expression [ 16 ].…”

Down‐regulation of genes coding for core RNAi components and disease resistance proteins via corresponding microRNAs might be correlated with successful Soybean mosaic virus infection in soybean

“…Recently, many miRNAs have been reported to mediate plant responses to biotic stresses, including viruses, bacteria and fungi (Niu et al ., ). For instance, the expression patterns of selected miRNAs from the model plants Arabidopsis thaliana (Hu et al ., ), Nicotiana benthamiana (Pacheco et al ., ), Solanum lycopersicum (Feng et al ., ; Naqvi et al ., ), Oryza sativa (Sun et al ., ; Xu et al ., ) and Cucumis sativus (Liu et al ., ), and non‐model plants including Citrus sinensis (Reyes et al ., ), Carica papaya (Liu et al ., ), Brassica campestris (Wang et al ., ) and Hibiscus cannabinus (Gao et al ., ), are modified by virus infections. Alterations of miRNA levels by virus infection also influences symptom development and disease proliferation.…”

“…Alterations of miRNA levels by virus infection also influences symptom development and disease proliferation. RNA viruses from different genera or families, such as Cucumber mosaic virus (CMV; Cucumovirus ) (Feng et al ., ), Turnip mosaic virus (TuMV; Potyvirus ) (Wang et al ., ), Cucumber green mottle mosaic virus (CGMMV; Tobamovirus ) (Liu et al ., ), Papaya meleira virus (PMeV; unclassified dsRNA virus) (Abreu et al ., ), Citrus psorosis virus (CPsV; Ophiovirus ) (Reyes et al ., ), Oilseed rape mosaic tobamovirus (ORMV; Tobamovirus ) (Hu et al ., ), Rice black‐streaked dwarf virus (RBSDV; Fijivirus ) (Sun et al ., ; Xu et al ., ), Hibiscus chlorotic ringspot virus (HCRSV; Carmovirus ) (Gao et al ., ), Potato virus X (PVX; Potexvirus ) (Pacheco et al ., ) and the DNA virus Tomato leaf curl virus (ToLCV; Begomovirus ) (Naqvi et al ., ), have all been reported to regulate host miRNA expression. These results indicate that the regulation of plant–virus interactions by miRNAs may be a common feature, and highlight the importance of further mining and determination of the functions of miRNAs during viral infections in different plant species.…”

Citrus Psorosis Virus Movement Protein Contains an Aspartic Protease Required for Autocleavage and the Formation of Tubule-Like Structures at Plasmodesmata

“…Citrus psorosis virus (CPsV), the type member of the Aspiviridae family (formerly Ophioviridae), genus Ophiovirus (40,41), is a three-partite, nonenveloped, negativesense, single-stranded RNA (ssRNA) virus. RNA 1 encodes a 280-kDa replicase (42) as well as a 24-kDa protein that affects microRNA (miRNA) maturation (43) and has RNA silencing-suppressing activity (44). RNA 2 encodes a protein of 54 kDa (named here MP CPsV ), which displays several features of a MP (45,46) and has RNA silencingsuppressing activity as well (44).…”