BPH resistance evaluation
To conduct the BPH resistance test at the seedling stage, eight seedlings of each line were placed in a plastic cup, 10 cm in diameter, and infested with six second to third instar BPHs per plant at the third-leaf stage (approximately 15 days). The plant survival rate of each cup was recorded 5–7 days after BPH infestation. Four 15-day-old seedlings of OE, knockout, and NIP were transplanted into a plastic bucket (30 cm in diameter), and normal management practices were performed. Each bucket was infested with second to third instar BPHs, at a density of 30 insects per shoot, when the plants began heading (approximately 75 days). Thereafter, the green shoots of each plant were counted when the knockout lines died after BPH infestation (approximately 21 days). Here, the green shoot rate, taken as the plant survival rate, was used to indicate the BPH resistance level of adult plants. A higher rate indicates a stronger resistance against BPH. Three cups or buckets were designed for each test, and each test was repeated three times.