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Numerous studies have shown that transcription factors are important in regulating plant responses to environmental stress. However, specific functions for most of the genes encoding transcription factors are unclear. In this study, we used mRNA profiles generated from microarray experiments to deduce the functions of genes encoding known and putative(More)
Like other eukaryotes, plants use DICER-LIKE (DCL) proteins as the central enzymes of RNA silencing, which regulates gene expression and mediates defense against viruses. But why do plants like Arabidopsis express four DCLs, a diversity unmatched by other kingdoms? Here we show that two nuclear DNA viruses (geminivirus CaLCuV and pararetrovirus CaMV) and a(More)
The cauliflower mosaic virus transactivator, TAV, controls translation reinitiation of major open reading frames on polycistronic RNA. We show here that TAV function depends on its association with polysomes and eukaryotic initiation factor eIF3 in vitro and in vivo. TAV physically interacts with eIF3 and the 60S ribosomal subunit. Two proteins mediating(More)
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(More)
To successfully infect plants, viruses must counteract small RNA-based host defense responses. During infection of Arabidopsis, Cauliflower mosaic pararetrovirus (CaMV) is transcribed into pregenomic 35S and subgenomic 19S RNAs. The 35S RNA is both reverse transcribed and also used as an mRNA with highly structured 600 nt leader. We found that this leader(More)
Several RNA silencing pathways in plants restrict viral infections and are suppressed by distinct viral proteins. Here we show that the endogenous trans-acting (ta)siRNA pathway, which depends on Dicer-like (DCL) 4 and RNA-dependent RNA polymerase (RDR) 6, is suppressed by infection of Arabidopsis with Cauliflower mosaic virus (CaMV). This effect was(More)
BACKGROUND Cauliflower mosaic virus (CaMV) and Rice tungro bacilliform virus (RTBV) belong to distinct genera of pararetroviruses infecting dicot and monocot plants, respectively. In both viruses, polycistronic translation of pregenomic (pg) RNA is initiated by shunting ribosomes that bypass a large region of the pgRNA leader with several short (s)ORFs and(More)
Alternative splicing usually leads to an increase in the number of gene products that can be derived from a single transcript. Here, a different and novel use of alternative splicing--as a means to control the amount of a potentially toxic gene product in the plant pararetrovirus Cauliflower mosaic virus (CaMV)--is reported. About 70 % of the CaMV 35S RNA,(More)
Two important hallmarks of RNA silencing in plants are (1) its ability to self-amplify by using a mechanism called transitivity and (2) its ability to spread locally and systemically through the entire plant. Crucial advances have been made in recent years in understanding the molecular mechanisms of these phenomena. We review here these recent findings,(More)