September 16, 2020

The apple scar skin disease was first re- ported 60 years ago in China ( Manchuria) with the name “Manshu-sabika-byo” (19). Twenty years later, two apple. Cause These diseases are caused by Apple scar skin viroid. Many infected cultivars of apple or pear do not express symptoms of disease. Apple scar skin viroid(ASSVd), a pathogenic RNA viroid, infects apple and pear trees. To determine if ASSVd can also infect apricot, we performed reverse.

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Groups of 20 whiteflies were transferred to 5 healthy cucumber plants.

In pear, in vitro therapy followed by apical meristem culture can be used to eliminate the viroid Postman and Hadidi, The causal agent is controlled through the use of healthy propagation materials indexing programmes and, if necessary, the removal of diseased trees. In addition to the monomeric circular and monomeric linear bands, another band was observed in the whiteflies, which may correspond to replicative intermediates of viroid RNA.

Some RNA species possess stem loop structures similar to tRNAs, and the existence of other unknown RNAs with such structures, which can confer increased stability, is probable. Additionally, direct viroid transmission via any insect vector is thus far unknown. Identification of the herbaceous host range of Apple scar skin viroid and analysis of its progeny variants. The symptoms of ASSVd in apple are usually found at the calyx end of the fruit, and include scar skin reddish brown patches with brownish scar-like tissuecracking, or dapple spotting symptoms.

This experimental transfer also confirmed that the whitefly could take up naked RNA and transmit it, perhaps with the aid of certain whitefly proteins. Several workers have observed that the disease spread naturally to neighboring trees, 20,21 and ASSVd has been reported to be seed-borne but not seed-transmitted in apple.


Healthy plants were grown in an insect-proof growth chamber. Sequence alignment between the ubiquitin ligase mRNA and ASSVd primers indicated high sequence similarity between the 2, thus explaining why this amplicon was obtained Fig. RNA-mediated interference and reverse transcription control the persistence of RNA viruses in the insect model Drosophila.

EPPO Global Database

Biological properties of apple scar skin viroid: Knowledge Bank home Change location. In addition to direct damage, whiteflies act as vectors of other plant pathogens, especially viruses that belong to genera Begomovirus, Crinivirus and Torradovirus. Skon and Discussion A healthy Tv colony was maintained on seed-grown eggplant Solanum melongena.

In the susceptible cv. The twenty whiteflies were then allowed access to groups of 5 healthy cucumber seedlings at the one-true-leaf stage. A healthy Tv colony was maintained on seed-grown eggplant Solanum melongena. Acta Horticulture ; Kyriakopoulou PE, Hadidi A.

Apple scar skin viroid naked RNA is actively transmitted by the whitefly Trialeurodes vaporariorum

These plants are always in close enough contact for viable viroid-insect-plant transmission. Click here to view. Molecular characterization of Apple scar skin viroid from Himalayan wild cherry.

Before identifying the role of CsPP2 in viroid transmission, we examined whitefly-mediated transmission of viroid RNA alone. The viroid, therefore, also exists in DNA form in the whitefly. Although the amplified fragment was not affected by this treatment, it disappeared when the whitefly DNA was incubated with DNase and then examined using PCR not shown.

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Apple scar skin viroid

We also demonstrated that the ASSVd-CsPP2 complex exists in vitro and in cucumber phloem, which suggests a mechanism for passage of the viroid from plants to whiteflies. ASSVd isolates were maintained on cucumber and bean.

The DNA form of a retroviroid-like element is involved in recombination events with itself and with the plant genome. Because some insects are known to possess endogenous reverse transcription activity, 18 total DNA of the whitefly was isolated and tested for a possible DNA form of the viroid using PCR.


Transmission to apple seedling of low molecular weight RNA from apple scar skin-diseased trees. We also present evidence for the acquisition and transfer of naked RNA viroid transcripts by the insect vector under in vitro conditions and a potential role of CsPP2 in viroid transmission.

Whiteflies can also affect hosts by producing a sticky secretion known as honeydew, which prevents leaves from functioning efficiently and acts as a substrate for fungi sooty molds.

Bulletins of Nagano Hort. Cookies on Plantwise Knowledge Bank Like most websites we use cookies. A faint band corresponding to the ubiquitin ligase mRNA was also observed when using healthy cucumber phloem. Archives of Virology ; Potato leafroll virus-assisted aphid transmission of potato spindle tuber viroid to potato leafroll virus-resistant potato.

Here, we demonstrated that the glasshouse whitefly acts as a vector for a pathogenic viroid RNA ASSVd known to propagate in plants, yeast Avocado sunblotch viroid and Chlamydomonas Eggplant latent viroid. Nucleic acid transfer between plants is a phenomenon which is likely to occur in many ways in nature. Enhanced resolution of circular and linear molecular forms of viroid and viroid-like RNA by electrophoresis in a discontinuous-pH system.

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Because these pathogens are non-protein-coding, they recruit host proteins to perform all of their major functions, including replication, trafficking and pathogenesis. Dapple symptoms, which develop nearer to harvest, usually appear on the red-skinned cultivars e. To explore zpple identity of this DNA form, rolling circle amplification RCA was performed using viroidliferous and healthy whiteflies.