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Carica papaya microRNAs are responsive to Papaya meleira virus infection.

Abreu PM, Gaspar CG, Buss DS, Ventura JA, Ferreira PC, Fernandes PM - PLoS ONE (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Núcleo de Biotecnologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil.

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.

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Related in: MedlinePlus

Symptoms of PMeV infection in Carica papaya.As opposed to most viruses, PMeV appears to reside primarily in lactifers, where it modifies potassium levels and osmotic balance, leading to rupture of cells and exudation of fluid and translucent latex from the fruits (A) and young leaves. The latex oxidises after atmospheric exposure, resulting in small necrotic lesions on the edges of young leaves (B) and a sticky latex on the fruits (C) that makes them unacceptable for consumption.
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pone-0103401-g001: Symptoms of PMeV infection in Carica papaya.As opposed to most viruses, PMeV appears to reside primarily in lactifers, where it modifies potassium levels and osmotic balance, leading to rupture of cells and exudation of fluid and translucent latex from the fruits (A) and young leaves. The latex oxidises after atmospheric exposure, resulting in small necrotic lesions on the edges of young leaves (B) and a sticky latex on the fruits (C) that makes them unacceptable for consumption.

Mentions: Papaya sticky disease, or “meleira”, is an important disease of the papaya (Carica papaya L.) that is capable of causing complete crop loss. Papaya tissues contain lactifers that maintain latex under high pressure so that it exudes upon injury as part of the defense mechanisms of the plant [26]. Tissues infected with papaya sticky disease spontaneously exude a translucent form of latex that is rapidly oxidised and darkens, rendering the fruit unsalable [27] (Figure 1A-C). The causal agent of sticky disease has been identified as Papaya meleira virus (PMeV), a 12 kbp dsRNA virus that presents as 50 nm spherical particles in infected tissues [28]. In contrast to most viruses, PMeV appears to reside primarily in lactifers where it modifies potassium levels and the osmotic balance, leading to rupture of cells and latex exudation [29].


Carica papaya microRNAs are responsive to Papaya meleira virus infection.

Abreu PM, Gaspar CG, Buss DS, Ventura JA, Ferreira PC, Fernandes PM - PLoS ONE (2014)

Symptoms of PMeV infection in Carica papaya.As opposed to most viruses, PMeV appears to reside primarily in lactifers, where it modifies potassium levels and osmotic balance, leading to rupture of cells and exudation of fluid and translucent latex from the fruits (A) and young leaves. The latex oxidises after atmospheric exposure, resulting in small necrotic lesions on the edges of young leaves (B) and a sticky latex on the fruits (C) that makes them unacceptable for consumption.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4114745&req=5

pone-0103401-g001: Symptoms of PMeV infection in Carica papaya.As opposed to most viruses, PMeV appears to reside primarily in lactifers, where it modifies potassium levels and osmotic balance, leading to rupture of cells and exudation of fluid and translucent latex from the fruits (A) and young leaves. The latex oxidises after atmospheric exposure, resulting in small necrotic lesions on the edges of young leaves (B) and a sticky latex on the fruits (C) that makes them unacceptable for consumption.
Mentions: Papaya sticky disease, or “meleira”, is an important disease of the papaya (Carica papaya L.) that is capable of causing complete crop loss. Papaya tissues contain lactifers that maintain latex under high pressure so that it exudes upon injury as part of the defense mechanisms of the plant [26]. Tissues infected with papaya sticky disease spontaneously exude a translucent form of latex that is rapidly oxidised and darkens, rendering the fruit unsalable [27] (Figure 1A-C). The causal agent of sticky disease has been identified as Papaya meleira virus (PMeV), a 12 kbp dsRNA virus that presents as 50 nm spherical particles in infected tissues [28]. In contrast to most viruses, PMeV appears to reside primarily in lactifers where it modifies potassium levels and the osmotic balance, leading to rupture of cells and latex exudation [29].

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Núcleo de Biotecnologia, Universidade Federal do Espírito Santo, Vitória, Espírito Santo, Brazil.

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.

Show MeSH
Related in: MedlinePlus