Monopartite begomoviruses and their associated satellites form unique disease complexes that have emerged as a serious threat to agriculture worldwide. It is well known that frequent recombination contributes to the diversification and evolution of geminiviruses. In this study, we identified a novel defective satellite molecule (RecSat) in association with Tobacco leaf curl Yunnan virus (TbLCYN...

Geminiviruses, like all viruses, rely on the host cell machinery to establish a successful infection, but the identity and function of these required host proteins remain largely unknown. Tomato yellow leaf curl Sardinia virus (TYLCSV), a monopartite geminivirus, is one of the causal agents of the devastating Tomato yellow leaf curl disease (TYLCD). The transgenic 2IRGFP N. benthamiana plants, ...

Tomato golden mosaic virus (TGMV), a member of the geminivirus family, requires a single virus-encoded protein for DNA replication. We show that the TGMV replication protein, AL1, also acts during transcription to specifically repress the activity of its promoter. An earlier study established that AL1 binds to a 13-bp sequence (5'-GGTAGTAAGGTAG) that is essential for activity of the TGMV replic...

The geminivirus replication factor AL1 interacts with the plant retinoblastoma-related protein (pRBR) to modulate host gene expression. The AL1 protein of tomato golden mosaic virus (TGMV) binds to pRBR through an 80-amino-acid region that contains two highly predicted alpha-helices designated 3 and 4. Earlier studies suggested that the helix 4 motif, whose amino acid sequence is strongly conse...

The genome of the tomato yellow leaf curl virus (TYLCV), a Bemisia tabaci-transmitted geminivirus, was cloned. All clones obtained were of one genomic molecule, analogous to DNA A of African cassava mosaic virus. Nucleotide sequence analysis of the TYLCV genome showed that it comprises 2787 nucleotides, encoding six open reading frames, two on the virion strand and four on the complementary str...

Despite having single stranded DNA genomes that are replicated by host DNA polymerases, viruses in the family Geminiviridae are apparently evolving as rapidly as some RNA viruses. The observed substitution rates of geminiviruses in the genera Begomovirus and Mastrevirus are so high that the entire family could conceivably have originated less than a million years ago (MYA). However, the existen...

We report a new strategy for cloning DNA of the plant-infecting geminiviruses that is based on PCR amplification with primers overlapping the sequence of a restriction site in the viral genome. This method reduces the time and work necessary to obtain biologically active geminivirus DNAs and could be used for other DNA viruses having circular genomes, such as the animalinfecting circoviruses. G...

Numerous plant RNA viruses have associated with them satellite (sat) RNAs that have little or no nucleotide sequence similarity to either the viral or host genomes but are completely dependent on the helper virus for replication. We report here on the discovery of a 682-nt circular DNA satellite associated with tomato leaf curl geminivirus (TLCV) infection in northern Australia. This is the fir...

A versatile green fluorescent protein (GFP) expression cassette containing the replication origins of the monopartite begomovirus Tomato yellow leaf curl Sardinia virus (TYLCSV) is described. Transgenic Nicotiana benthamiana plants containing one copy of the cassette stably integrated into their genome were superinfected with TYLCSV, which mobilized and replicated the cassette as an episomal re...