Evaluation of the effects of exogenously applied RNase A on the vegetative growth of hop latent viroid-infected Cannabis sativa

Sustainable agriculture emphasizes resource conservation, ecosystem resilience with minimal environmental impact and effective plant disease management. Hop latent viroid (HLVd), a circular, single-stranded RNA pathogen, poses a growing threat to cannabis crops, causing stunted growth and reduced flower quality, along with a significant reduction in cannabinoid and terpene production. This study investigated the impacts of exogenous RNase A application on the growth of HLVd-infected cannabis plants during the vegetative stage. A completely randomized design evaluated plant growth responses to different exogenous RNase A concentrations (6, 9 and 12 µg mL−1) in hydroponic solution after a 14-day period. RNase A (12 µg mL−1) treatment resulted in significantly higher plant height, fresh leaf mass, and fresh and dry stem mass compared with untreated HLVd-infected plants (p < 0.05). In several cases, these growth parameters were statistically similar to those observed in healthy HLVd-free plants. RT-qPCR analysis indicated that HLVd remained detectable in all RNase-treated plants, with no significant reduction in viroid load. Analysis of the nutrient solution showed that exogenous RNase A effectively degraded HLVd, as no amplification was detected after 12 h in any treated solution, whereas HLVd remained detectable in the non-treated control. These findings indicate that, while exogenous RNase A is not effective in eliminating HLVd infection in plant systems, it can degrade extracellular viroid RNA in hydroponic systems and may reduce the risk of transmission through recirculating nutrient solutions. This study provides a foundation for further research exploring RNase-based approaches for managing viroid infections in valuable crops.