Distribution of Lily symptomless virus in tissues of Lanzhou lily (Lilium davidii var. unicolor) by fluorescence in situ hybridisation.

Lily symptomless virus (LSV) is one of the main viruses that endanger Lilium davidii var. unicolor, causing billions of losses to the lily planting industry every year. The distribution of viruses in plants is uneven and identifying the virus-free tissue regions in lily is crucial for obtaining virus-free resources through in vitro culture. In this study, Lilium davidii var. unicolor carrying LSV was used as the experimental material. RNA fluorescent probes were designed and prepared based on the genomic sequence of LSV. RNA in situ hybridization experiments were conducted on the meristematic tissues (root tips and stem tips), mature tissues (leaves, stem segments, pedicel), and flower organs (ovaries) to observe the distribution of LSV in different tissues. It was found that no fluorescence signal was detected in the apical meristematic tissue (0.65-0.8 mm × 0.2-0.25 mm) and pith cells of stem. Strong LSV signal expression was observed in the root tips, epidermis, cortex and vascular bundles of stem and pedicel, epidermis, palisade tissue, spongy tissue and vein vascular bundles of leaves, ovary and ovule. Due to the difficulty in the regeneration and differentiation of pith cells in stem segments, the apical meristem of Lilium davidii var. unicolor can be used as the starting material for obtaining virus-free resources through in vitro culture.