Introduction The whitefly Bemisia tabaci Genn. (Homoptera:Aleyrodidae) has caused millions of dollars worth of crop losses in tropical and subtropical agricultural regions in the five continents of the world (Brown, 1994). Besides the direct damage caused by B. tabaci (plant nutrient loss; physiological disorders; honey dew excretions, etc), the sweet potato or cotton whitefly is an efficient v...

The nomenclature of papaya viruses has been a source of confusion, primarily because symptomatology has been used extensively for describing papaya viruses. Although the literature is confusing and causal viruses for each of the diseases are not well identified, it appears that papaya viral diseases can generally be grouped as ring spot, mosaic and leaf curl, associated with poty, potex and gem...

Short-interfering RNAs (siRNAs), the molecular markers of posttranscriptional gene silencing (PTGS), are powerful tools that interfere with gene expression and counter virus infection both in plants and animals. Here, we report the effect of temperature on geminivirus-induced gene silencing by quantifying virus-derived siRNAs and by evaluating their distribution along the virus genome for isola...

DNA geminiviruses are thought to be targets of RNA silencing. Here, we characterize small interfering (si) RNAs-the hallmarks of silencing-associated with Cabbage leaf curl begomovirus in Arabidopsis and African cassava mosaic begomovirus in Nicotiana benthamiana and cassava. We detected 21, 22 and 24 nt siRNAs of both polarities, derived from both the coding and the intergenic regions of these...

Some geminiviruses are transmitted by the whitefly Bemisia tabaci in a circulative manner. These geminiviruses are assigned to the genus Begomovirus within the family Geminiviridae. The route followed by begomoviruses in their insect vector and the velocity of translocation of the various viruses seem to be intrinsic to the whitefly, not to the virus. Subsequent to ingestion during feeding on a...

Geminiviruses are plant-infecting viruses characterized by a single-stranded DNA (ssDNA) genome. Geminivirus-derived proteins are multifunctional and effective regulators in modulating the host cellular processes resulting in successful infection. Virus-host interactions result in changes in host gene expression patterns, reprogram plant signaling controls, disrupt central cellular metabolic pa...