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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #367948

Research Project: Detection, Identification, and Characterization of New and Emerging Viral and Bacterial Diseases of Ornamental Plants

Location: Floral and Nursery Plants Research

Title: First report of Pyrus pyrifolia cryptic virus infecting pear in Korea

item CHO, IN-SOOK - Rural Development Administration - Korea
item YANG, CHANG YOUL - Rural Development Administration - Korea
item KWON, SUN-JUNG - Rural Development Administration - Korea
item YOON, JU-YEON - Rural Development Administration - Korea
item KWON, TAE-RYONG - Rural Development Administration - Korea
item Hammond, John
item LIM, HYOUN-SUB - Chungnam National University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2020
Publication Date: 4/28/2020
Citation: Cho, I., Yang, C., Kwon, S., Yoon, J., Kwon, T., Hammond, J., Lim, H. 2020. First report of Pyrus pyrifolia cryptic virus infecting pear in Korea. Plant Disease.

Interpretive Summary: Virus infections cause losses of yield or quality in many crops. Viruses are especially significant in vegetatively propagated perennial crops, as infections are passed on to plants produced from infected mother plants, and additional viruses may accumulate as a result of either mechanical or vectored transmission during the life of the crop. Even viruses that cause little obvious damage in a single infection may exacerbate symptoms and losses in a mixed infection. An ARS scientist collaborated with Korean scientists to determine the cause of disease symptoms on a pear tree in Korea, including small leaves, stunted growth, and reduced yields. The team identified four viruses previously known to infect pear in Korea, and also Pyrus pyrifolia cryptic virus (PpCV), only reported previously from Japan. Further testing of 16 additional pear samples revealed seven additional infections of PpCV, suggesting that this virus is widely distributed in Korea. Because PpCV was identified in mixed infections, no association of this virus with particular symptoms could be identified, and further study is required to identify any effect of PpCV infection on tree growth and yield.

Technical Abstract: Pyrus pyrifolia cryptic virus (PpCV), a new member of the genus Alphapartitivirus with three double-stranded (ds) RNA molecules (dsRNA1, 2 and 3) in the family Partitiviridae, was recently identified from pear (Pyrus pyrifolia) in Japan (Osaki et al. 2017). In 2017, a pear cv. Gamcheonbae showing small leaves, stunted growth, and reduced fruit yield was observed in Naju, Korea. Total RNA was extracted from the symptomatic leaves and subjected to high throughput sequencing (HTS). A cDNA library was prepared using an Illumina TruSeq Stranded Total RNA kit with Ribo-Zero Plant, and sequenced by the Illumina HiSeq 4000 system. Analysis of sequence data performed with BLASTN search against the NCBI viral genome database allowed the identification of two contigs sharing 99.93 and 100% nucleotide (nt) identities with the dsRNA2 and dsRNA3 of PpCV (GenBank LC221824 and LC221825, respectively). Additionally, four known pear infecting viruses were also detected in the sample: Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV), Apricot latent virus (ApLV) and Apple green crinkle associated virus (AGCaV). To confirm the presence of PpCV, virus-specific primer pairs dsRNA2F/dsRNA2R (5’-AAAGATACGC-TTGCGCAGAA-3’/5’-ATCTAGGAGCCAGCATGGTC-3’) and dsRNA3F/dsRNA3R (5’-ACCAGAATGTCTAACGACGAAGC-3’/5’- CTTGGACATCGTAGGCTCCGA-3’) were designed based on the contig sequences. RT-PCR products of the expected 771 bp and 943 bp were cloned and sequenced. The sequences (GenBank accession no. LC488171 and LC488172) showed 99.87 and 99.89% identity with the corresponding sequences of dsRNA2 and dsRNA3 segments from PpCV, respectively. To survey the sanitary status of other pear trees, 16 pear samples were collected from various cultivars and subjected to RT-PCR detection for PpCV. Of these, 7 samples were positive for the virus suggesting the common presence of PpCV in Korean pear trees, which was not clearly associated with symptoms on the infected pear trees. Further study is needed to understand the effect of PpCV on pear growth. To our knowledge, this is the first report of PpCV infecting pear in Korea.