Altered patterns of gene expression in Arabidopsis elicited by cauliflower mosaic virus (CaMV) infection and by a CaMV gene VI transgene

Cauliflower mosaic virus (CaMV) gene VI protein (P6) is an important determinant of symptom expression. Differential display polymerase chain reaction (PCR) was used to identify changes in gene expression in Arabidopsis elicited by a P6 transgene that causes a symptomatic phenotype. We used slot blot hybridization to measure the abundance of mRNAs complementary to 66 candidate PCR products in transgenic, CaMV-infected, and uninfected Arabidopsis plants. CaMV-infected and P6 transgenic plants showed broadly similar changes in abundance of mRNA species. In P6 transgenic plants we detected 18 PCR products that showed unambiguous changes in abundance plus another 15 that showed more limited changes (approximately twofold). CaMV-infected plants showed 17 unambiguous and 13 limited changes. Downregulated species include those encoding a novel, phenol-like sulfotransferase, and a glycine-rich, RNA-binding protein. Up-regulated species included ones encoding an myb protein, glycine-rich and stress-inducible proteins, and a member of a previously unreported gene family. CaMV infection causes alterations in expression of many Arabidopsis genes. Transgene-mediated expression of P6 mimics virus infection in its effect on host gene expression, providing a potential mechanism for this process.