Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/14/2007
Publication Date: 8/1/2007
Citation: Dardick, C.D. 2007. Comparative expression profiling of Nicotiana benthamiana leaves systemically infected with three fruit tree viruses. Molecular Plant-Microbe Interactions. 20(8):1004-1017. Interpretive Summary: Viruses are the most destructive pathogens for stone fruit production and cause substantial losses in yield and reduced fruit quality. Plum pox virus is the most economically important, however, other viruses, such as tomato ringspot virus and prunus necrotic ringspot virus, also cause considerable damage. Unfortunately, little is known about how these viruses cause disease, and molecular and genetic factors involved. Such information will provide opportunities for new and creative ways to control these pathogens. Here, we used a relatively new technology called gene expression profiling to identify plant genes that respond to infection by each virus. Because this technology is not yet available for fruit tree species, this work was conducted in tobacco as a model. Over 1,000 genes were identified that respond to one or more viruses, and it was possible to link many of these changes to the virus symptoms observed in the infected plants.
Technical Abstract: Plant viruses induce a wide array of disease symptoms and cytopathic effects including alterations of chloroplasts, ribosomes, and cell membranes. While some of these changes are virus specific, many appear to be common even among diverse viruses, although the underlying molecular determinants are largely unknown. To identify gene expression changes that are concomitant with virus symptoms, we performed expression profiling experiments on N. benthamiana leaves infected with one of three different fruit tree viruses that produce distinct symptoms: plum pox potyvirus (PPV- leaf distortion, mosaic), tomato ringspot nepovirus (ToRSV-tissue necrosis and general chlorosis), and prunus necrotic ringspot ilarvirus (PNRSV- subtle chlorotic mottling). The number of significant genes identified in each case was consistent with the severity of the observed symptoms: 1,041 (ToRSV), 679 (PPV), and 75 (PNRSV). Sixty-three percent of the gene expression changes found in PPV infected leaves were also altered by ToRSV, 88% of which changed in the same direction. Both PPV and ToRSV infected leaves showed repression of large numbers of genes controlling chloroplast function and photosynthesis. In contrast, PPV induced the expression of over 50 cytoplasmic ribosomal genes (56% of all small and large ribosome subunits), while ToRSV repressed the expression of smaller subsets of both chloroplast and cytoplasmic ribosomal genes. How these and other observed expression changes might be associated with symptom development is discussed.