Construction of efficient virus removal and micropropagation system for 'Yu Tai Yi Hao' chrysanthemum

'Yu Tai Yi Hao' (Chrysanthemum × morifolium Ramat.) is a perennial herbaceous plant from the Asteraceae family and Chrysanthemum genus.As the first officially approved tea chrysanthemum variety in the country, 'Yu Tai Yi Hao' has gained significant market demand due to its high tea (medicinal) value and nutritional content.However, 'Yu Tai Yi Hao' faces serious issues in propagation and cultivation, such as genetic degeneration and virus contamination in seedlings, which significantly hinder its widespread use and application.This study used new shoots of the 'Yu Tai Yi Hao' tea chrysanthemum as plant material to induce callus formation from stem cross-sections and differentiate adventitious buds into seedlings. RT-PCR was employed to detect four viruses: Chrysanthemum B virus (CVB), Chrysanthemum stunt virus (CSVd), Chrysanthemum chlorotic mottle virus (CChMVd), and Tomato spotted wilt virus (TSWV).Plants testing positive for viruses were selected, and their shoot-tip explants were used for further propagation and culture. The study optimized the combinations of hormone types and concentrations at various culture stages to provide a reference for developing a virus-free tissue culture system for 'Yu Tai Yi Hao'. The results showed that in the induction of callus and differentiation of adventitious buds for 'Yu Tai Yi Hao', a medium containing MS, 2.0 mg/L 6-BA, and 0.3 mg/L NAA achieved 100% induction and differentiation rates, with an average differentiation coefficient of 42.83 and a maximum of 90. In the rooting medium (MS + 0.1 mg/L NAA), 100% rooting rate was achieved in 15 days.After 5 days of hardening treatment, the seedlings were transplanted into a growth medium with a 1:1 peat moss: perlite ratio, achieving a survival rate of 100%. Virus testing on regenerated plants revealed that 9 samples were free of CVB and CSVd viruses, with a 100% virus elimination rate, while 2 samples were free of CChMVd and TSWV, resulting in a 22.2% virus elimination rate. This study has preliminarily developed a virus-free tissue culture system for 'Yu Tai Yi Hao', providing technical support for the high-quality and efficient industrial propagation of virus-free seedlings for 'Yu Tai Yi Hao'. It also lays the foundation for exploring targeted virus elimination techniques, virus resistance, as well as for establishing a genetic transformation system for 'Yu Tai Yi Hao' and conducting related gene functional verification studies.