Multiplication and Distribution of Rice Yellow Dwarf Phytoplasma in Infected Tissues of Rice and Green Rice Leafhopper Nephotettix cincticeps.

Multiplication and distribution of rice yellow dwarf phytoplasma in infected tissues of rice and the vector, green rice leafhopper (Nephotettix cincticeps), were demonstrated by dot hybridization using DNA probes for phytoplasma DNA. Phytoplasma DNA was first detected in rice plants at 20 days after the termination of a 3-day inoculation feeding of phytoplasma-exposed insect vectors. The amount of DNA in infected rice tissues started to increase rapidly at 30 days after the feeding, leveled off by 40 days, and remained at the same high level for up to 80 days. In RYD-infected rice tissues, the amount of phytoplasma does not correlate to the severity in chlorosis. In insects, phytoplasma DNA was detected at 10 days after the termination of a 3-day acquisition access feeding on RYD-infected plants, and the amount increased rapidly at 30-40 days after the feeding. Phytoplasma DNA was detected mainly in the abdomen and thorax at 25 days after the feeding, but mainly in the head at 50 days.