A common set of developmental miRNAs are upregulated in Nicotiana benthamiana by diverse begomoviruses

BACKGROUND: Begomoviruses are single-stranded DNA viruses that cause economically important diseases of many crops throughout the world and induce symptoms in plants, including enations, leaf curling and stunting, that resemble developmental abnormalities. MicroRNAs (miRNAs) are small endogenous RNAs that are involved in a variety of activities, including plant development, signal transduction and protein degradation, as well as response to environmental stress, and pathogen invasion. RESULTS: The present study was aimed at understanding the deregulation of miRNAs upon begomovirus infection. Four distinct begomoviruses African cassava mosaic virus (ACMV), Cabbage leaf curl virus (CbLCuV), Tomato yellow leaf curl virus (TYLCV) and Cotton leaf curl Multan virus/Cotton leaf curl betasatellite (CLCuV/CLCuMB), were used in this study. Ten developmental miRNA were studied. N. benthamiana plants were inoculated with begomoviruses and their miRNA profiles were analysed by northern blotting using specific miRNA probes. The levels of most developmental miRNA were increased in N. benthamiana by TYLCV, CLCuMV/CLCuMB and CbLCuV infection with a common pattern despite their diverse genomic components. However, the increased levels of individual miRNAs differed for distinct begomoviruses, reflecting differences in severity of symptom phenotypes. Some of these miRNA were also common to ACMV infection. CONCLUSIONS: Our results have shown a common pattern of miRNAs accumulation upon begomovirus infection. It was found that begomoviruses generally increase the accumulation of miRNA and thus result in the decreased translation of genes involved in the development of plants. Identification of common miRNAs that are deregulated upon begomovirus infection may provide novel targets for control strategies aimed at developing broad-spectrum resistance.