Investigating Apple Rubbery Wood Virus 2: HTS-Based Detection in Hungary and Involvement of sRNA-Based Regulation...

Area of Science:

• Plant Pathology
• Virology
• Molecular Biology

Background:

• Pomme fruits are vegetatively propagated, increasing susceptibility to viral infections.
• Apple rubbery wood disease, caused by apple rubbery wood virus 2 (ARWV2), affects apple and pear trees, leading to reduced xylem lignification and branch flexibility.

Purpose of the Study:

• To re-analyze small RNA high-throughput sequencing (HTS) datasets to detect ARWV2 presence in Hungary.
• To investigate the correlation between ARWV2 infection, gene expression related to lignification, and disease symptoms.

Main Methods:

• Re-analysis of existing small RNA (sRNA) HTS datasets.
• Validation of HTS data using RT-PCR.
• RT-PCR based survey for ARWV2 in various fruit tree species.
• Analysis of sRNA patterns, including viral small interfering RNAs (vsiRNAs), sRNAs, and microRNAs (miRNAs), targeting the lignin biosynthetic pathway.

Main Results:

• ARWV2 infection was confirmed in several apple cultivars and other fruit trees, including pears, quince, and rootstocks, in Hungary.
• Many infected trees did not exhibit typical rubbery wood symptoms, indicating latent infections.
• Gene expression changes in lignification pathways were not directly correlated with the presence of ARWV2, explaining its frequent latent occurrence.

Conclusions:

• ARWV2 is present in Hungary across multiple fruit tree species, often asymptomatically.
• The lack of direct correlation between viral presence and lignification gene expression contributes to the virus's frequent latent state.
• Variable viral titre, sequence diversity, and mixed infections pose challenges for reliable ARWV2 diagnostics, necessitating further research.