• A rapid and reproducible 14-dpi indoor assay was established by integrating seedling medium culture with RRSV inoculation via viruliferous brown planthoppers (BPHs). • A highly virulent BPH colony was generated and validated (overall acquisition rate ∼74.44%), enabling standardized inoculation conditions (e.g., 16 insects per cup, 48-h feeding). • A two-trait, 0-6 scoring framework (plant height reduction ratio + number of severely stunted plants) was developed to classify accessions into four resistance levels (R, MR, MS, S). • The platform supports high-throughput germplasm screening (105 accessions) and shows strong consistency between molecular detection (RT-PCR/qRT-PCR) and field validation outcomes. Rice ragged stunt virus (RRSV) is one of the most damaging viral threats to rice production in Asia and other major rice-growing regions. Most commercial rice cultivars exhibit high susceptibility to RRSV, and the currently available resistance evaluation systems are time-consuming and lack reproducibility. Hence, there is an urgent need to develop a standardized, reproducible, accurate, and high-throughput system for large-scale screening of rice germplasm resistant to RRSV. In this study, we established an integrated method using seed culture, controlled RRSV transmission by viruliferous brown planthoppers (BPH; ∼74.44% RRSV carrying rate), and seedling phenotyping. It was initially optimized using four representative rice accessions (two indica and two japonica ). This method enables resistance evaluation at the seedling stage within 14 days post-inoculation (dpi). RRSV loads detection via RT-PCR and qRT-PCR and field trials investigation further validated the laboratory-based evaluation outcomes. Two parameters, reduction in average plant height and the ratio of severely stunted seedlings, were integrated into a 0-6 scoring system to classify rice accessions into four resistance levels: resistant, moderately resistant, moderately susceptible, and susceptible. This method enables early, reproducible, and high-throughput evaluation of rice resistance to RRSV. The scoring framework provides a basis for resistance level classification, which will be useful for the development of RRSV-resistant varieties.
Li et al. (Sun,) studied this question.