RECENT HORIZONTAL TRANSFERS OF THE COX1 INTRON IN SOLANACEAE DUE TO A FUNCTIONAL HOMING ENDONUCLEASE

ABBONA, CC; KUSHNIR, S; GEELEN, D; PALMER, JD; SÁNCHEZ-PUERTA, MV

Potrero de los Funes, San Luis - Argentina

Congreso; XLVII Annual Meeting SAIB (Argentine Society for Biochemistry and Molecular Biology); 2011

Sociedad Argentina de Investigaciones de bioquimica y biologia molecular (SAIB)

Plant mitochondria are unique in their propensity to acquire genes by horizontal transfer. The most stunning case of horizontal gene transfer (HGT) involves a group I intron in the mitochondrial gene cox1. We have previously estimated 80 transfer events among >800 angiosperms. This intron encodes a putatively functional homing endonuclease that may promote the intron?s frequent horizontal acquisitions. To study the endonuclease activity, we designed an experimental approach based on somatic cell hybridization. Given that the ideal plant group for somatic genetics is the family Solanaceae, we first undertook an extensive survey to find members with the cox1 intron. Out of 426 solanaceous species examined by PCR and sequencing, only three clades contained the intron. Analyses of intron evolution suggested three independent and recent intron acquisitions in Solanaceae. Cybrids (Cytoplasmic Hybrids), obtained from protoplast fusions between intron-containing and intron-lacking solanaceous plants, were analyzed to test the functionality of the intron-encoded homing endonuclease. Examination of cox1 genes from cybrid indicated that the intron colonized the cox1 copy from the intronless plant. These results constitute strong evidence indicating that the cox1 intron-encoded homing endonuclease is functional and active in plants.