Molecular detection of rice tungro bacilliform virus (RTBV) on weed host in South Sulawesi

Abstract Rice tungro bacilliform Virus (RTBV) is one of the viruses that cause tungro disease in rice plants causing leaf yellow and plant stunting. Some weed species have also been described as potential hosts for RTBV in addition to rice. However, RTBV cannot be diagnosed in weeds only by looking at their morphological symptoms because weeds infected with RTBV do not show typical symptoms. Hence this research was conducted to detect the presence of RTBV molecularly on several weed hosts in rice fields in South Sulawesi. The polymerase Chain Reaction technique with coat protein gene-specific primers was used to detect RTBV. A total of 29 leaf samples consisting of 12 weed species collected from Sidrap, Pinrang, Maros, and Gowa were then extracted genomic DNA from the leaf samples for PCR analysis. The results of PCR analysis showed that weed samples that tested positive for RTBV were Panicum repens (Lawawoi/Sidrap), Echinochloa crusgalli (Lawawoi/Sidrap), Cyperus difformis (Lanrang/Sidrap), Echinochloa crusgalli (Palangga/Gowa), Fimbristilys miliacea (Lanrang/Sidrap), and Eleusine indica (Lawawoi/Sidrap) which were indicated by the presence of RTBV virus DNA fragments with 430 bp in length in all these weeds. Weeds infected by RTBV formed 2 clusters. The first cluster consisted of RTBV in P.repens and E.crusgalli from Lawawoi/Sidrap, RTBV in C.difformis and F.miliacea from Lanrang/Sidrap, and RTBV in E.indica from Palangga/Gowa. At the same time, the second cluster consisted of RTBV in E.indica from Lawawoi/Sidrap.