Sequencing of a Field Isolate of the Tomato Yellow Leaf Curl Virus

Geminiviruses are single-stranded DNA viruses that cause severe economic damage to food crops worldwide including the US. Tomato yellow leaf curl virus (TYLCV) is a major pathogen of tomato worldwide, causing extensive crop loss, with the main control being the use of insecticides to limit the whitefly vector. Our long-term goal is to understand how the virus interacts with the host causing disease. This project involves the characterization of a strain of TYLCV, which was shown to be present in plants showing symptoms of an infection in a region south of San Antonio. This was the first report of a case of TYLCV in Texas. We will be sequencing the entire TYLCV genome and testing infectivity of the virus. Rolling circle amplification (RCA) has been performed on DNA samples isolated from plants exhibiting symptoms typical of a TYLCV infection. Following restriction of the RCA products, a unit-length genomic fragment of the vial genome is currently being inserted into a pUC-based cloning vector. The entire genome will be sequenced and infectious clones constructed, which will comprise tandem dimers of the TYLCV genome. The viral transcripts produced during the infection will be characterized, and the replication kinetics of TYLCV determined. The outcome of these experiments will increase our knowledge concerning transcription and replication in TYLCV and form the basis for the development of novel strategies for control of TYLCV, based on disruption of interactions between the virus and host. Partially supported by UTSA Work Study Research Training Program.