M. Chiurazzi et al., ENHANCEMENT OF SOMATIC INTRACHROMOSOMAL HOMOLOGOUS RECOMBINATION IN ARABIDOPSIS BY THE HO ENDONUCLEASE, The Plant cell, 8(11), 1996, pp. 2057-2066
The HO endonuclease promotes gene conversion between mating-type allel
es in yeast by a DNA double-strand break at the site of conversion (th
e MAT-Y/Z site). As a first step toward understanding the molecular ba
sis of homologous recombination in higher plants, we demonstrate that
expression of HO in Arabidopsis enhances intrachromosomal recombinatio
n between inverted repeats of two defective beta-glucuronidase (gus) g
enes (GUS(-) test construct). One of these genes has the Y/Z site. The
two genes share 2.5 kb of DNA sequence homology around the HO cut sit
e. Somatic recombination between the two repeats was determined by usi
ng a histochemical assay of GUS activity. The frequency of Gus(+) sect
ors in leaves of F-1 plants from a cross between parents homozygous fo
r the GUS(-) test construct and HO, respectively, was in-fold higher t
han in F-1 plants from a cross between the same plant containing the G
US(-) test construct and a wild-type parent. Polymerase chain reaction
analysis showed restoration of the 5' end of the GUS gene in recombin
ant sectors. The induction of intrachromosomal gene conversion in Arab
idopsis by HO reveals the general utility of site-specific DNA endonuc
leases in producing targeted homologous recombination in plant genomes
.