title: Heat shock induces a loss of rRNA-encoding DNA repeats in Brassica nigra.
abstract: Stress-induced mutations may play an important role in the evolution of plants. Plants do not sequester a germ line, and thus any stress-induced mutations could be passed on to future generations. We report a study of the effects of heat shock on genomic components of Brassica nigra Brassicaceae. Plants were submitted to heat stress, and the copy number of two nuclear-encoded single-copy genes, rRNA-encoding DNA (rDNA) and a chloroplast DNA gene, was determined and compared to a nonstressed control group. We determined whether genomic changes were inherited by examining copy number in the selfed progeny of control and heat-treated individuals. No effects of heat shock on copy number of the single-copy nuclear genes or on chloroplast DNA are found. However, heat shock did cause a statistically significant reduction in rDNA copies inherited by the F1 generation. In addition, we propose a DNA damage-reppair hypothesis to explain the reduction in rDNA caused by heat shock.
authors.affiliation: Department of Biology, Washington University, St. Louis, MO 63130, USA.
authors.forename: E R
authors.initials: ER
authors.lastname: Waters
authors.forename: B A
authors.initials: BA
authors.lastname: Schaal
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics; D051936:Centromere Protein B; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics; D004247:DNA / Q000235:genetics*; D004254:DNA Nucleotidyltransferases / Q000235:genetics; D004268:DNA-Binding Proteins; D004331:Drosophila melanogaster / Q000235:genetics; D019143:Evolution, Molecular; D012091:Repetitive Sequences, Nucleic Acid; D018626:Retroelements / Q000235:genetics*; D016415:Sequence Alignment; D017385:Sequence Homology; D012756:Sheep / Q000235:genetics; D013045:Species Specificity; D019895:Transposases; D014981:Xenopus / Q000235:genetics
chemical_list: D001324:Autoantigens; D051936:Centromere Protein B; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D018626:Retroelements; D004247:DNA; D004254:DNA Nucleotidyltransferases; D019895:Transposases