Analysis of Double-Stranded RNAs from Cherry Trees with Stem Pitting in California

Area of Science:

• Plant virology
• Molecular biology
• Horticultural pathology

Background:

• Cherry trees are susceptible to various diseases, including stem pitting, which affects fruit production.
• Double-stranded RNA (dsRNA) elements are often associated with plant viral pathogens.

Purpose of the Study:

• To identify and characterize dsRNA species associated with stem pitting in Bing sweet cherry trees.
• To investigate the relationship between specific dsRNA species and disease symptoms.

Main Methods:

• Isolation and characterization of dsRNA species from infected cherry trees.
• Development of reverse transcription-polymerase chain reaction (RT-PCR) assays for specific dsRNA detection.
• Graft inoculation experiments to assess transmissibility and pathogenicity.

Main Results:

• Five distinct dsRNA species were identified, including an 8.5-kbp dsRNA identified as sour cherry green ring mottle virus (CGRMV).
• Larger dsRNA species (8.5- and 9.0-kbp) were graft-transmissible, while smaller ones were cryptic.
• RT-PCR detected CGRMV or the 9.0-kbp dsRNA in approximately 14% of diseased samples.
• CGRMV and 9.0-kbp dsRNA induced wood-marking in Mazzard seedlings but not in Bing cherry.

Conclusions:

• Sour cherry green ring mottle virus (CGRMV) is associated with stem pitting symptoms, but it may not be the sole causal agent.
• The identified dsRNA species exhibit varying degrees of transmissibility and pathogenicity.
• The precise causal agent(s) of cherry stem pitting require further investigation.