Reciprocal chromosome translocation associated with TDNA-insertion mutation in Arabidopsis: genetic and cytological analyses of consequences for gametophyte development and for construction of doubly mutant lines.
Chromosomal rearrangements may complicate construction of Arabidopsis with multiple TDNA-insertion mutations. Here, crossing two lines homozygous for insertions in AtREV3 and AtPOLH (chromosomes I and V, respectively) and selfing F1 plants yielded non-Mendelian F2 genotype distributions: frequencies of +/++/+ and 1/1 2/2 progeny were only 0.42 and 0.25%. However, the normal development and fertility of double mutants showed AtPOLH-1 and AtREV3-2 gametes and 1/1 2/2 embryos to be fully viable. F2 distributions could be quantitatively predicted by assuming that F1 selfing produced inviable (1,2) and (+,+) gametophytes 86% of the time. Some defect intrinsic to the F1 selfing process itself thus appeared responsible. In selfing AtREV3 (+/2 ) single mutants, imaging of ovules and pollen showed arrest or abortion, respectively, of half of gametophytes; however, gametogenesis was normal in AtREV3 ( 2/2 ) homozygotes. These findings, taken together, suggested that T-DNA insertion at AtREV3 on chromosome I had caused a reciprocal I-V translocation. Spreads of meiosis I chromosomes in selfing AtREV3 (+/2 ) heterozygotes revealed the predicted cruciform four-chromosome structures, which fluorescence in situ hybridization showed to invariably include both translocated and normal chromosomes I and V. Sequencing of the two junctions of T-DNA with AtREV3 DNA and the two with gene At5g59920 suggested translocation via homologous recombination between independent inverted-repeat T-DNA insertions. Thus, when crosses between TDNA-insertion mutants yield anomalous progeny distributions, TDNA-linked translocations should be considered.
Curtis
Marc J
MJ
Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA.
Belcram
Katia
K
Bollmann
Stephanie R
SR
Tominey
Colin M
CM
Hoffman
Peter D
PD
Mercier
Raphael
R
Hays
John B
JB
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000254:growth & development; D005787:Gene Frequency; D005838:Genotype; D006579:Heterozygote; D017404:In Situ Hybridization, Fluorescence; D008957:Models, Genetic; D016254:Mutagenesis, Insertional; D009154:Mutation; D011058:Pollen / Q000235:genetics / Q000254:growth & development; D014178:Translocation, Genetic; D000099270:Y-Family DNA Polymerases
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D004259:DNA-Directed DNA Polymerase; C036483:T-DNA; C479807:AtREV3 protein, Arabidopsis; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases