Figure 1.

Genomic flexibility, as measured by intrachromosomal HR and T-DNA integration, is increased in fas mutants. (A) Recombination marker constructs. The β-glucuronidase (GUS; uidA) sequences have an overlap (indicated by ‘U') either in the direct (left) or inverted (right) orientation. Recombination (indicated by ‘x') between the two overlapping sequences produces a functional GUS gene. (B, C) Visualization of recombination events by histochemical GUS staining of leaves from a FAS1 control (B), and a fas1-2 plant homozygous for the inverted repeat-type recombination reporter (GU-US/GU-US) (C). An arrowhead in (B) indicates GUS-positive cells. (D, E) Frequency distribution histograms showing the proportions of plants with a given number of blue GUS spots in the direct repeat (D) and inverted repeat (E) populations. (F, G) Mutants fas1-2 and fas2-2 (ecotype Nossen), fas2-1 (ecotype Ler), and fas2-4 (ecotype Col), and the corresponding wild-type plants were inoculated with A. tumefaciens. (F) Plates showing growth of roots and tumors of Nossen, and its mutants fas1-2 and fas2-2, photographed 1 month after infection. (G) Efficiency of T-DNA integration as represented by the percentage of root segments that produced tumors. Error bars indicate standard error (s.e.). Data (means±s.e.) were taken from 10 plants of each type.