a spontaneous dominant-negative mutation within a 35satmyb90 transgene inhibits flower pigment production in tobacco自发的显性负突变在35 satmyb90转基因抑制花色素在烟草生产.pdfVIP

A Spontaneous Dominant-Negative Mutation within a 35S::AtMYB90 Transgene Inhibits Flower Pigment Production in Tobacco 1 1 2 Jeff Velten *, Cahid Cakir , Christopher I. Cazzonelli 1 Plant Stress and Water Conservation Laboratory, United States Department of Agriculture - Agricultural Research Service, Lubbock, Texas, United States of America, 2 Australian Research Council - Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia Abstract Background: In part due to the ease of visual detection of phenotypic changes, anthocyanin pigment production has long been the target of genetic and molecular research in plants. Specific members of the large family of plant myb transcription factors have been found to play critical roles in regulating expression of anthocyanin biosynthetic genes and these genes continue to serve as important tools in dissecting the molecular mechanisms of plant gene regulation. Findings: A spontaneous mutation within the coding region of an Arabidopsis 35S::AtMYB90 transgene converted the activator of plant-wide anthocyanin production to a dominant-negative allele (PG-1) that inhibits normal pigment production within tobacco petals. Sequence analysis identified a single base change that created a premature nonsense codon, truncating the encoded myb protein. The resulting mutant protein lacks 78 amino acids from the wild type C-terminus and was confirmed as the source of the white-flower phenotype. A putative tobacco homolog of AtMYB90 (NtAN2) was isolated and found to be expressed in flower petals but not leaves of all tobacco plants tested. Using transgenic tobacco constitutively expressing the NtAN2 gene confirmed the NtAN2 protein as t