| Description: |
Rice (Oryza sativa), one of the important crops in the Philippines is prone to various diseases. Rice Tungro virus (RTV) is the most damaging virus disease of rice, which cause orange to yellow leaf discoloration, reduced tillering and severe stunting. RTV is a composite disease associated with two different viruses, Rice tungro bacilliform virus (RTBV) and Rice tungro spherical virus (RTSV). Rice Orange Leaf Phytoplasma (ROLP) belongs to the "Candidatus Phytoplasma asteris" 16SrI-B subgroup, cause destructive yield loss, with plants exhibiting moderate stunting and golden or orange leaf discoloration, and eventually leading to leaf senescence. Rice plants severely infected with either ROLP or RTV at seedling stage are lethal. Green leafhopper (GLH) Nephotettix virescens is the active transmitter of RTV and recently it was found that it can also transmit ROLP. In the present study, diagnostic field visit was carried out at IRRI fields, Laguna, Philippines to collect samples from the rice breeding lines showing varied symptoms of yellow to orange discoloration of the leaves, severe stunting and reduced tillers. A total of 93 samples were collected from 5 plots distantly located from each other in late 2023 WS and early DS at early to late tillering stages. DNA and leaf sap were extracted from the individual sample and tested for the presence of ROLP by nested PCR and RTV (RTBV and RTSV) by DAS-ELISA. Results showed that mixed infection of ROLP+RTV showed the highest percentage infection (37%) followed by 33% RTV alone, 12% ROLP alone, 12% ROLP + RTSV and 6 % is negative to both. It is concluded that, there is co-infection of RTV and ROLP under field conditions. The nature of RTV and ROLP interaction and transmission by the GLH is yet to be ascertained. Hence, it is important to study the existence of the co-infection of virus and phytoplasma thus to protect the crop from severe infection and to avoid epidemics under field conditions. Key words: Rice, ROLP, RTBV, RTSV, ELISA, PCR |