Source: CropBiotech Update

Tomato is an important vegetable crop to many countries, but is plagued by a variety of viral diseases. One of the most devastating viruses is a group with the generic name Tomato Leaf Curl Virus (ToLCV), which are transmitted by whiteflies, and which cause tomato leaf curl disease (ToLCD). Efforts to breed tomato varieties resistant to the disease have hitherto been unsuccessful, since natural sources of resistance are not available.

Genetically engineering resistance remains a viable alternative to equipping tomato with protection against ToLCV. One method is introducing pathogen-derived resistance (PDR), by either allowing transgenic tomato to produce a shorter version of the viral protein (protein-mediated resistance) or RNA (RNA-mediated resistance). Shelly Praveen and colleagues of the Indian Agricultural Research Institute investigate the possibility of “Engineering tomato for resistance to tomato leaf curl disease using viral rep gene sequences” in a recent issue of the Plant Cell, Tissue, and Organ Culture journal.

Scientists transformed, via Agrobacterium¸ tomato cells with replicase (rep) gene sequences of ToLCV. Transgenic plants were tested for disease resistance by exposing them to a high population of whiteflies reared on virus-infected plants. Researchers recorded a high level of resistance to ToLCV and inheritability of the transgene, up to the T2 stage following challenge inoculation with the virus. The mechanism of resistance, according to researchers, appears to be RNA-mediated, since plants carried the untranslatable anti-sense rep gene.

Subscribers to the journal can read the complete article at http://dx.doi.org/10.1007/s11240-005-7858-8.